Scopes of pipes and symbols used for pipe products

Areas of application of pipe products

1. In the oil and gas industry:

• drill pipes - for drilling exploration and production wells;
• casing pipes - to protect the walls of oil and gas wells from destruction, water ingress into wells, to separate oil and gas reservoirs from each other;
• tubing - for the operation of boreholes in oil production.

2. For pipelines:

• water and gas pipelines;
• oil pipelines (field, for main pipelines).

3. In construction.

4. In mechanical engineering:

• boiler pipes - for boilers of various designs;
• cracking pipes - for pumping combustible oil products under high pressure and for the manufacture heating elements ovens;
• structural pipes - for the manufacture of various machine parts.

5. For the production of vessels and cylinders.

Pipe Conventions

The first number above the line indicates the outer diameter of the pipe in mm, the second - the wall thickness in mm. This is followed by the designation of the dimension or multiplicity of the pipes. If the pipe is measured, then its length is indicated in mm, if it is unmeasured, then the letters “cr” are after the multiplicity value. For example: a pipe that is a multiple of 1 m 25 cm is indicated by 1250 kr. If the pipe is unmeasured, then the multiplicity (dimension) is not indicated.

After the multiplicity, the accuracy class of the pipe is put. Two accuracy classes are produced along the length of the pipe:

1 - with trimming ends and deburring outside the mill line;

2 - with cutting in the mill line.

Limit deviations along the length are less for pipes of the 1st accuracy class. If the accuracy class is not specified, then the pipe is of ordinary accuracy.

The first number under the line indicates the quality group: A, B, C, D. This is followed by the steel grade and GOST steel.

After the word trumpet, in some cases, letters are placed denoting the following:

“T” - heat-treated pipes;

"C" - pipes with zinc coating;

“P” - threaded pipes;

"Pr" - pipes of precision manufacturing;

"M" - with a clutch;

“H” - pipes for thread rolling;

"D" - pipes with a long thread;

“P” - pipes of increased manufacturing strength.

2 . Classification steel pipes

There are several ways to classify pipes.

By production method:

1. Seamless:

a)rolled, in hot and cold conditions;

b)cold-formed in a cold and warm state;

c)pressed.

2. Welded:

a) rolled, in hot and cold conditions;

b) electric resistance welding;

c) gas electric welding.

According to the profile of the pipe section:

1. round;
2. Shaped - oval rectangular, square, three-, six- and octahedral, ribbed, segmental, teardrop-shaped and other profiles.

According to the size of the outer diameter (Dnmm):

1. Small sizes (capillary): 0.3 - 4.8;
2. Small sizes: 5 - 102;
3. Medium sizes: 102 - 426;
4. Large sizes: over 426.

Depending on the ratio of the outer diameter to the pipe wall thickness:

№	Name	Dn/ ST	ST/Dn
1	Extra thick-walled	5,5	0,18
2	thick-walled	5,5 — 9	0,18 — 0,12
3	Normal	9,1 — 20	0,12 — 0,05
4	Thin-walled	20,1 — 50	0,05 — 0,02
5	Extra thin-walled	50	0,02

Pipe class:

1. Pipes 1-2 classes made from carbon steels. Class 1 pipes, the so-called standard and gas pipes, are used in cases where there are no special requirements. For example, when building scaffolding, fences, supports, for laying cables, irrigation systems, as well as for localized distribution and supply of gaseous and liquid substances.
2. Pipes 2nd class used in high and low pressure main pipelines for supplying gas, oil and water, petrochemical products, fuels and solids.
3. Class 3 pipes used in pressure and high temperature systems, nuclear engineering, oil cracking pipelines, furnaces, boilers, etc.
4. Pipes 4 classes designed for exploration and exploitation of oil fields, they are used as drilling, casing and auxiliary.
5. Class 5 pipes- structural - used in the production of transport equipment (automotive industry, car building, etc.), in steel structures (bridge cranes, masts, drilling rigs, supports), as furniture elements, etc.
6. Pipes 6th class are used in mechanical engineering for the manufacture of cylinders and pistons of pumps, bearing rings, shafts and other parts of machines, tanks operating under pressure. There are pipes of small outer diameter (up to 114 mm), medium (114-480 mm) and large (480-2500 mm and more).

According to the standards for the supply of pipes (GOSTs):

1. general specifications standards establish comprehensive technical requirements for the assortment, quality characteristics of pipes, acceptance rules and test methods;
2. range standards, which include standards for pipes of a wide range of applications used in a wide variety of industries National economy, provide limit deviations linear dimensions of pipes (diameter, wall thickness, length, etc.), curvature and mass;
3. technical requirements standards define the basic technical requirements for pipes for a wide range of purposes, they specify steel grades, mechanical properties (tensile strength, yield strength, relative elongation, in some cases - impact, toughness of the pipe material); surface quality requirements, as well as requirements for technological testing by hydraulic pressure, flattening, expanding, bending, etc. In addition, the technical requirements standards for pipes stipulate acceptance rules, special requirements for marking, packaging, transportation and storage;
4. test method standards define general test methods for hardness and impact strength, micro- and macro-structure control, determination of intergranular corrosion proneness, as well as pipe-specific test methods (bending, hydraulic pressure, beading, expanding, flattening, stretching, ultrasonic flaw detection and etc.)
5. standards for marking, packaging, transportation and storage rules stipulate requirements common to all types of cast iron and steel pipes, as well as fittings, for these final pipe production operations.

3. Characteristics of standards for pipe products

3.1. General issues standardization of pipe products

1. What is a state standard, where is it applied, who draws up and approves it?

Answer: GOST is a state standard that applies to the entire territory Russian Federation. Compilers - developers of GOSTs can be: research institutes, enterprises, organizations, regulatory authorities and laboratories. As a result, all materials according to the new GOST or the revision of the old one converge in the State Committee for Standardization, which gives a final assessment and approves the GOST for a product, product or the whole process.

1. Who can cancel GOST or make changes or additions to it?

Answer: The GOST is valid for 5 years, however, during this period, changes and additions are allowed, which are also introduced and approved by the Committee for Standardization of the Russian Federation (currently URALNITI has such authority). Reprinting of GOSTs is prohibited and prosecuted as a violation of the law; this means that no one, except for the above organizations, can make changes to the standard and no one has the right not to comply with the requirements set out in it.

1. 3. What typical sections are there in GOSTs for pipe products, what is their content?

Answer: GOSTs containing requirements for pipes are usually drawn up according to one scheme and contain the following sections:

• assortment;
• technical requirements for this product;
• acceptance rules;
• methods of control and testing;
• marking, packaging, transportation and storage.

Section "Assortment". It provides for limiting the production of pipes in a certain range of diameters (external and internal), wall thicknesses and lengths in accordance with this GOST. All types of permissible deviations in geometric parameters are also given here: in diameter, wall thickness, length, ovality, chamfer, wall thickness, curvature. This section of GOST provides examples of symbols for pipes with different requirements for geometric parameters, mechanical properties, chemical composition and other technical characteristics.

Section "Technical requirements". Contains a list of steel grades from which pipes can be made, or GOSTs for chemical composition different brands become. This section contains standards for mechanical properties (tensile strength, yield strength, relative elongation, hardness, impact strength, relative narrowing, etc.) for various steel grades at different test temperatures. The types of heat treatment and technological tests are discussed: bending, expanding, flattening, beading, hydro and pneumatic tests.

In this section of almost any GOST, requirements are set for the state of the surface and unacceptable and acceptable defects are listed.

It should be noted a characteristic feature of GOSTs - the absence of references to product standards.

One of the important requirements of GOSTs is the condition of the ends of the pipes: pipes that go further for welding must be chamfered at an angle of 30 -35 ° to the end, with end blunting, and all pipes with a wall thickness of up to 20 mm. should have straight cut ends.

Section "Rules of acceptance". It explains how acceptance should be carried out in quantitative and qualitative terms. Norms of samples for testing and control for various parameters are negotiated.

Section "Methods of control and testing". General rules for sampling and methods for surface control and geometric parameters. In addition, it is given short info, with reference to the relevant regulatory documentation, on the conduct of technological tests and control of mechanical properties, including non-destructive methods. From this section you can find out: what GOSTs should be used if it is necessary to carry out ultrasonic testing, tests for intergranular corrosion, and hydraulic pressure tests.

Section "Marking, packaging, transportation and storage". It does not contain information, as it redirects to GOST 10692 - 80.

1. 4. Why do GOSTs stipulate the rules for acceptance of products?

Answer: There are certain acceptance rules for each type of pipe. For example, for bearing pipes, standards for metallographic tests (micro- and macrostructure), the content of non-metallic inclusions (sulfides, oxides, carbides, globules, micropores) are established; for aviation pipes additional condition is to control the size of the decarburized layer and the presence of hairs (on the Magnoflox device), for stainless steel - for intergranular corrosion, etc.

1. 5. Show the use of GOST.

Answer: Example: ordered pipe 57*4mm. from steel grade 10, length multiple of 1250 mm., increased accuracy in diameter according to GOST 8732-78, gr. In and clause 1.13 of GOST 8731-74.

I. Let's determine the permissible deviations by geometric parameters:

A) by diameter: according to table 2 of GOST 8732-78, the diameter tolerance will be± 0.456mm;

B) wall thickness: according to table 3 of GOST 8732-78, the wall thickness tolerance will be +0.5mm, -0.6mm.

D) by length: according to clause 3 of GOST 8732-78, the minimum length of the pipe is 5025mm, the maximum is 11305mm.

E) pipe ovality: diameter tolerance* 2;

E) difference in wall thickness of the pipe;

G) pipe curvature.

Symbol of the pipe in our example: pipe 57p * 4.0 * 1250kr GOST8732-78.

B 10 GOST 8732-74

II. Since the pipes are ordered according to group B of GOST 8731-74, it is necessary to check the compliance of their actual mechanical properties with the properties indicated in table 2 of the named GOST:

A) tear resistance

B) metal flow test;

C) specimen elongation test.

1. Inspection of surfaces: unacceptable and acceptable defects.

IV. Trimming the ends of pipes and a method for determining the depth of the defect.

1. Since point 1.13 is in the order, it is necessary to carry out technological tests, in this case, check two samples for flattening.
2. The steel grade is determined by the sparking method.

VII. Marking, packaging and storage (see GOST 10692-80).

1. 6. What are technical specifications, who writes them?

Answer: Specifications is a regulatory agreement concluded between the manufacturer of pipes (cylinders) and the consumer of these products.

The preparation of specifications is preceded by technical specifications, project development, numerous analyzes and examinations.

Technical specifications are approved by the technical managers of the enterprise - manufacturer and enterprise - consumer, and then registered with UralNITI.

1. 7. What is the difference between technical specifications and GOST?

Answer: A feature of TS is the use of non-standard requirements and characteristics (dimensions, tolerances, defects, etc.) in them. One should not think that TS is “weaker” than GOST and the technology for manufacturing products according to TS can be simplified. On the contrary, a number of specifications contain more stringent requirements for manufacturing accuracy, surface finish, etc., for which the buyer pays the manufacturer.

A distinctive point is the flexibility of technical conditions, the ability to make some kind of change or addition "on the go" that does not require a long time for its approval. When working with specifications, the standardization system, one-time products, and individual orders are widely used.

1. 8. Scope of technical conditions.

Answer: There are technical conditions of the national scale, for example. Specifications for all types of food products, as well as intradepartmental specifications, for example, specifications for the supply of pipe blanks between Pervouralsky Novotrubny Plant and Oskolsky EMK. Within our enterprise, there are 30 specifications for the supply of billets from pipe-rolling to pipe-drawing shops, and for all pipe products we apply up to 500 different specifications.

3.2. Characteristics of products manufactured in accordance with the main state standards

1. GOST - 10705 - 80 - electric welded steel pipes

This standard applies to straight-seam steel pipes with a diameter of 8 to 520 mm with a wall thickness of up to 10 mm inclusive, made of carbon steel. It is used for pipelines and structures for various purposes.

but)random length (pipes are not the same length):

• with a diameter of up to 30 mm. - not less than 2 m;
• with a diameter of 30 to 70 mm. - not less than 3 m;
• with a diameter of 70 to 152 mm. – not less than 4 m;
• with a diameter of more than 152 mm. - not less than 5 m.

In a batch of pipes of random length, up to 3% (by weight) of shortened pipes is allowed:

• not less than 1.5 m - for pipes with a diameter of up to 70 mm;
• not less than 2 m - for pipes with a diameter of up to 152 mm;
• not less than 4 m - for pipes with a diameter of up to 426 mm.

Pipes with a diameter of more than 426 mm are made only in random lengths.

b)measured length(same length)

• with a diameter of up to 70 mm - from 5 to 9 m;
• with a diameter of 70 to 219 mm - from 6 to 9 m;
• with a diameter of 219 to 426 mm - from 10 to 12 m.

in)multiple length any multiplicity (2,4,6,8,10-fold 2) not exceeding the lower limit set for measured pipes. In this case, the total length of multiple pipes should not exceed the upper limit of measuring pipes. The allowance for each magnification is set to 5 mm (GOST 10704-91).

Two accuracy classes are produced along the length of the pipe:

1. with cutting edges and deburring outside the mill line;

2. with cutting in the mill line.

The maximum deviation along the total length of multiple pipes does not exceed:

• +15 mm - for pipes of the 1st accuracy class;
• +100 mm - for pipes of the 2nd accuracy class (according to GOST 10704-91).

The curvature of the pipes should not exceed 1.5 mm per 1 meter of length.

Depending on the quality indicators, pipes of the following groups are manufactured:

BUT- with standardization of mechanical properties from calm, semi-quiet and boiling steel grades St2, St3, St4 according to GOST 380-88;

B– with standardization of the chemical composition from calm, semi-quiet and boiling steel grades 08, 10, 15 and 20 according to GOST 1050-88. And steel grade 08Yu according to GOST 9045-93.

IN- with standardization of mechanical properties and chemical composition of calm, semi-calm and boiling steel grades VST2, VST3, VST4 (categories 1, 23-6), as well as calm, semi-quiet and boiling steel grades 08, 10, 15, 20 according to GOST 1050- 88 and steel grades 08Yu according to GOST 90-45-93 for diameters up to 50 mm.

D- with standardization of the test hydraulic pressure.

They produce heat-treated pipes (over the entire volume of the pipe or a welded joint) and pipes without heat treatment.

2. GOST 3262 - 75 - steel water and gas pipes

This standard applies to non-galvanized and galvanized steel welded pipes with threaded or knurled cylindrical threads and without threads. They are used for water and gas pipelines, heating systems, as well as for parts of water and gas pipeline structures. The length of the pipes is from 4 to 12 meters.

When determining the mass of non-galvanized pipes, the relative density of steel is assumed to be 7.85 g/cm. Galvanized pipes are 3% heavier than non-galvanized ones.

Along the length of the pipe are made:

but)random lengthfrom 4 to 12 m.

According to GOST 3262-75, up to 5% of pipes with a length of 1.5 to 4 m are allowed in a batch.

b)measured or multiple length from 4 to 8 m (by order of the consumer), and from 8 to 12 m (by agreement between the manufacturer and the consumer) with an allowance for each cut of 5 mm and a maximum deviation for the entire length plus 10 mm.

According to GOST 3262-75, the maximum deviations in the mass of pipes should not exceed + 8%.

The curvature of pipes per 2 m of length should not exceed:

• 2 mm - with conditional pass up to 20 mm;
• 1.5 mm - with nominal bore over 20 mm.

Pipe ends must be cut square.

Galvanized pipes must have a continuous zinc coating of the entire outer and inner surface with a thickness of at least 30 microns. The absence of the specified coating is allowed on the ends and threads of pipes and couplings.

3. GOST 8734 - 75 - cold-formed seamless steel pipes

Manufactured:

but)random lengthfrom 1.5 to 11.5 m;

b)measured lengthfrom 4.5 to 9 m with an allowance for each cut of 5 mm.

No more than 5% of random length pipes not shorter than 2.5 m are allowed in each batch of pipes of specific length.

According to GOST 8734-75, the curvature of any pipe section per 1 m of length should not exceed:

• 3 mm - for pipes with a diameter of 5 to 8 mm;
• 2 mm - for pipes with a diameter of 8 to 10 mm;
• 1.5 mm - for pipes with a diameter of more than 10 mm.

4. GOST 8731 - 81 - seamless hot-formed steel pipes

This International Standard applies to hot-formed seamless pipes made of carbon, low-alloy, alloy steel for piping structures, machine parts and chemical purposes.

Pipes made from ingots are not allowed to be used for transporting hazardous substances (classes 1, 2, 3), explosive and flammable substances, as well as steam and hot water.

Indicators technical level, established by this standard, are provided for the highest quality category.

Technical requirements

Pipe dimensions and limit deviations must comply with those given in GOST 8732-78 and GOST 9567-75.

Depending on the normalized indicators, pipes should be manufactured in the following groups:

BUT- with standardization of mechanical properties of steel grades St2sp, St4sp, St5sp, St6sp according to GOST 380-88;

B- with standardization of the chemical composition from calm steel grades according to GOST 380-88, 1st category, group B, with a normal mass fraction of manganese according to GOST 1050-88, as well as from steel grades according to GOST 4543-71 and GOST 19281-89;

IN- with standardization of mechanical properties and chemical composition of steel grades according to GOST 1050-88, GOST 4543-71, GOST 19281-89 and GOST 380-88;

G– with standardization of the chemical composition of steel grades according to GOST 1050-88, GOST 4543-71 and GOST 19281-89 with control of mechanical properties on heat-treated samples. The norms of mechanical properties must comply with those specified in the standards for steel;

D- with standardization of test hydraulic pressure, but without standardization of mechanical properties and chemical composition.

Pipes are made without heat treatment. At the request of the consumer, the pipes must be made heat-treated.

5. GOST - 20295 - 85 - welded steel pipes

They are used in main gas and oil pipelines.

This standard applies to steel welded straight-seam and spiral-seam pipes with a diameter of 159-820 mm, used for the construction of main gas and oil pipelines, oil product pipelines, technological and field pipelines.

Main parameters and dimensions .

Pipes are made of three types:

1. straight-seam with a diameter of 159-426 mm, made by resistance welding with high-frequency currents;

2. spiral-seam - with a diameter of 159-820 mm, made by electric arc welding;

3. straight-seam - with a diameter of 530-820 mm, made by electric arc welding.

4.3. Questions about the steel grades used

1. 1. How are steels classified?

Answer: Steels are classified:

• by chemical composition: carbon, alloyed (low -, medium -, high-alloyed);
• by structure: hypoeutectoid, hypereutectoid, ledeburitic (carbide), ferritic, austenitic, pearlitic, martensitic;
• by quality: ordinary quality, high-quality, high-quality, especially high-quality;
• by application: structural, instrumental, with special operational properties (heat-resistant, magnetic, corrosion-resistant), with special physical properties.

1. 2. What is the symbol for steel grades? (examples).

Answer: All steels have their own marking, reflecting primarily their chemical composition. In the steel marking, the first digit indicates the content in hundredths of a percent. Then follow the letters of the Russian alphabet, indicating the presence of an alloying element. If there is no number after the letter, this means that the content of the alloying element is not more than one percent, and the numbers following the letter indicate its content as a percentage. Example: 12ХН3А - carbon content - 0.12%; chromium - 1.0%; nickel - 3.0%; High Quality.

1. 3. Decipher the following designations of steel grades:

20A, 50G, 10G2, 12X1MF, 38X2MYUA, 12X18H12T, 12X2MFSR, 06X16N15M2G2TFR - ID, 12X12M1BFR - Sh.

Answer:

• 20A - carbon content 0.2%, high quality;
• 50G - carbon content - 0.5%, manganese - 1%;
• 10G2 - carbon content - 0.1%, manganese - 2%;
• 12X1MF - carbon content - 0.12%, chromium - 1%, molybdenum, tungsten - up to 1%;
• 38X2MYUA - carbon content - 0.38%, chromium - 2%, molybdenum, aluminum - up to 1%, high quality;
• 12X18H12T - carbon content - 0.12%, chromium - 18%, nickel - 12%, titanium - up to 1%;
• 12X2MFSR - carbon content - 0.12%, chromium - 2%, molybdenum, tungsten, silicon, boron - up to 1%;
• 06Kh16N15M2G2TFR - ID - carbon content - 0.06%, chromium - 16%, nickel - 15%, molybdenum - 2%, manganese - 2%, titanium, tungsten, boron - up to 1%, vacuum - induction plus arc remelting;
• 12X12M1BFR - Sh - carbon content - 0.12%, chromium - 12%, molybdenum - 1%, niobium, tungsten, boron - up to 1%, slag remelting.

1. 4. How is the method of steel production reflected in the designations of steel grades?

Answer: V last years to improve the quality of steel, new methods of its smelting are used, which are reflected in the designations of steel grades:

• VD - vacuum - arc;
• VI - vacuum - induction;
• Ш - slag;
• PV - direct reduction;
• EPSH - electron slag remelting;
• ShD - vacuum - arc after slag remelting;
• ELP - electron - beam remelting;
• PDP - plasma - arc remelting;
• ISH - vacuum - induction plus electroslag remelting;
• IP - vacuum - induction plus plasma - arc remelting.

In addition to those listed, pipes are made from experimental steel grades with the following designations:

• EP - electrostal search;
• EI - electrostal research;
• ChS - Chelyabinsk steel;
• ZI - Zlatoust research;
• VNS - VIEM stainless steel.

According to the degree of deoxidation, steels are marked as follows: boiling - KP, semi-calm - PS, calm - SP.

1. 5. Tell about carbon steel grades.

Answer: Carbon steel is divided into structural steel and tool steel. Structural carbon steel is called steel containing up to 0.6% carbon (0.85% is allowed as an exception).

By quality, structural carbon steel is divided into two groups: ordinary quality and high-quality.

Steel of ordinary quality is used for non-critical building structures, fasteners, sheet metal, rivets, welded pipes. GOST 380-88 is installed on structural carbon steel of ordinary quality. This steel is smelted in oxygen converters and open-hearth furnaces and is divided into three groups: group A, supplied by mechanical properties; group B supplied by chemical composition and group C supplied by mechanical properties and chemical composition.

High-quality carbon structural steel is supplied in terms of chemical composition and mechanical properties, GOST 1050-88. It is used for parts operating under increased loads and requiring resistance to impact and friction: gears, axles, spindles, ball bearings, connecting rods, crankshafts, for the manufacture of welded and seamless pipes. Automatic carbon steels also belong to structural carbon steels. To improve cutting, sulfur, lead, and selenium are introduced into its composition. Pipes for the automotive industry are made from this steel.

Tool carbon steel is steel containing 0.7% or more carbon. Differs in hardness and durability and is divided into high-quality and high-quality.

Quality steel grades according to GOST 1435-90: U7, U8, U9, U10A, U11A, U12A, U13A. The letter "U" means carbon tool steel. The numbers behind the letter "U" show the average carbon content in tenths of a percent. The letter "A" at the end of the brand stands for high-quality steel. The letter "G" means increased content manganese. Chisels, hammers, stamps, drills, dies, and various measuring tools are made from tool carbon steel.

1. 6. Tell about alloyed steel grades.

Answer: In alloyed steel, along with the usual impurities (sulfur, silicon, phosphorus), there are alloying, i.e. binders, elements: chromium, tungsten, molybdenum, nickel, as well as silicon and manganese in an increased amount. Alloy steel has a high valuable properties that carbon steel does not have. The use of alloy steel saves metal, increases the durability of products.

The influence of alloying elements on the properties of steel:

• chromium - increases hardness,corrosion resistance;
• nickel - increases strength, ductility, corrosion resistance;
• tungsten - increases hardness, and red hardness, i.e. the ability to maintain wear resistance at high temperatures;
• vanadium - increases density, strength, resistance to impact, abrasion;
• cobalt - increases heat resistance, magnetic permeability;
• molybdenum - increases red hardness, strength, corrosion resistance at high temperatures;
• manganese - at a content of more than 1.0%, it increases hardness, wear resistance, resistance to shock loads;
• titanium - increases strength, corrosion resistance;
• aluminum - increases scale resistance;
• niobium - increases acid resistance;
• copper - reduces corrosion.

Rare earth elements are also introduced into special-purpose steels; several alloying elements can be present simultaneously in alloyed steels. By purpose, alloyed steels are divided into structural, tool and steels with special physical and chemical properties.

Structural alloy steel according to GOST 4543-71 is divided into three groups: high-quality, high-quality, extra high-quality. In high-quality steel, sulfur content is allowed up to 0.025%, and in high-quality steel - up to 0.015%. The scope of structural alloy steel is very large. The most widely used steels are:

• chromium, with good hardness, strength: 15X, 15XA, 20X, 30X, 30XPA, 35X, 40X, 45X
• manganese, characterized by wear resistance: 20G, 50G, 10G2, 09G2S (c. 5,8,9);
• chromium-manganese: 19KhGN, 20KhGT, 18KhGT, 30KhGA;
• siliceous and chrome-silicon, with high hardness and elasticity: 35XC, 38XC;
• chrome-molybdenum and chromium-molybdenum-vanadium, extra strong, resistant to abrasion: 30XMA, 15XM, 15X5M, 15X1MF;
• chromium-manganese-silicon steels (chromansil): 14KhGSA, 30KhGSA, 35KhGSA;
• chromium-nickel, very strong and ductile: 12X2H4A, 20XH3A, 12XH3A;
• chromium-nickel-tungsten, chromium-nickel-vanadium steels: 12Kh2NVFA, 20Kh2N4FA, 30KhN2VA.

Tool alloy steel is used for the manufacture of cutting, measuring and shock-punching tools. The most important elements of such steel are chromium, tungsten, molybdenum, manganese. Measuring tools are made from this steel - threaded gauges, staples (7HF, 9HF, 11HF); cutting - cutters, drills, taps (9XC, 9X5VF, 85X6NFT); stamps, press-forms (5XHM, 4X8V2). The most important tool alloy steel is high-speed. It is used in the manufacture of drills, cutters, taps. The main properties of this steel are hardness and red hardness. The alloying elements are tungsten, chromium, cobalt, vanadium, molybdenum - R6M3, R14F14, R10K5F5, etc.

1. 7. Tell about stainless steel grades.

Answer:

• Corrosion-resistant - high-chromium steel alloyed with nickel, titanium, chromium, niobium and other elements. Are intended for work in environments of different aggressiveness. For slightly aggressive environments, steels 08X13, 12X13, 20X13, 25X13H2 are used. Parts made of these steels operate outdoors, in fresh water, in wet steam and salt solutions at room temperature.

For environments of medium aggressiveness, steels 07X16H6, 09X16H4B, 08X17T, 08X22H6T, 12X21H5T, 15X25T are used.

For environments of increased aggressiveness, steels 08X18H10T, 08X18H12T, 03X18H12 are used, which have high resistance to intergranular corrosion and heat resistance. The structure of corrosion-resistant steels, depending on the chemical composition, can be martensitic, martensitic-ferritic, ferritic, austenitic-martensitic, austenitic-ferritic, austenitic.

• Cold-resistant steels must retain their properties at -40° C -80° C. The most widely used steels are: 20Kh2N4VA, 12KhN3A, 15KhM, 38Kh2MYuA, 30KhGSN2A, 40KhN2MA, etc.
• Heat-resistant steels are able to withstand mechanical loads at high temperatures (400 - 850° FROM). Steels 15Kh11MF, 13Kh14N3V2FR, 09Kh16N15M3B, and others are used for the manufacture of superheaters, blades steam turbines, high pressure pipelines. For products operating at higher temperatures, steels 15Kh5M, 16Kh11N2V2MF, 12Kh18N12T, 37Kh12N8G8MBF, etc. are used.
• Heat-resistant steels are able to resist oxidation and scale formation at temperatures of 1150 - 1250° C. for the manufacture of steam boilers, heat exchangers, thermal furnaces, equipment operating at high temperatures in aggressive environments, steel grades 12X13, 08X18H10T, 15X25T, 10X23H18, 08X20H14S2, etc. are used.
• Heat-resistant steels are intended for the manufacture of parts operating in a loaded state at a temperature of 600 ° C for a long period of time. These include: 12X1MF, 20X3MVF, 15X5VF, etc.

1. 8. Influence of harmful impurities on the quality of steel.

Answer: Most alloying elements are aimed at improving the quality of steels.

However, there are components of steel that adversely affect its quality.

• Sulfur - gets into steel from cast iron, and into cast iron - from coke and ore. Sulfur forms a compound with iron, located along the grain boundaries of steel. When heated up to 1000 -1200 ° With (for example, during rolling), it melts, the bond between the grains is weakened, and the steel is destroyed. This phenomenon is called red brittleness.
• Phosphorus - like sulfur, gets into steel from ores. It greatly reduces the ductility of steel, steel becomes brittle at ordinary temperatures. This phenomenon is called cold brittleness.
• Oxygen is partially dissolved in steel and is present in the form of non-metallic inclusions - oxides. Oxides are brittle, do not deform during hot processing, but crumble and loosen the metal. With an increase in oxygen content, the tensile strength and impact strength are significantly reduced.
• Nitrogen - is absorbed from the atmosphere by liquid metal during melting and is present in steel in the form of nitrides. Nitrogen lowers the toughness of carbon steels.
• Hydrogen - can be in steel in an atomic state or in the form of compounds with iron - hydrides. Its presence in large quantities leads to the appearance of internal stresses in the metal, which may be accompanied by cracks and ruptures (flakes). Titanium alloys are very sensitive to hydrogen saturation, where special measures are taken against metal hydrogenation.
• Copper - in high content (over 0.18%) in low-carbon steels significantly increases the tendency of steel to aging and cold brittleness.

4.4. Raw material for pipe production

The starting material for the production of seamless pipes is usually calm steel, for welded pipes, calm, semi-quiet and boiling steel are equally used.

Advantages of boiling steel: the size of the primary shrinkage cavity is smaller; complete absence of a secondary shrinkage cavity; less non-metallic inclusions; better surface quality; higher plasticity of the metal; the strength of the metal is lower, and the viscosity is higher; lower production cost.

Disadvantages of boiling steel: higher concentration of impurities; more subcortical blisters and more difficult to control the process of their formation; more intensive aging of the metal and less resistance to corrosion.

Advantages of calm steel: less concentration of harmful impurities; absence of subcortical blisters.

Disadvantages of calm steel: the size of the primary shrinkage cavity is larger; significant secondary shrinkage cavity; worse surface quality; lower viscosity of the metal; more expensive production.

For the manufacture of seamless pipes, boiling and semi-quiet steel is used only for less critical pipes, precisely because of the high concentration of impurities and a significant number of subcrustal bubbles, in recent years blowing has been used to improve the quality of pipe steel. liquid metal argon, evacuation, steel treatment with synthetic slags, additives of powder reagents. Steels with a high carbon content are used for the manufacture of large-diameter pipes, which are used in the oil industry as casing and drill pipes, as well as other pipes for critical purposes. Steels with a lower carbon content are used for the production of steam boilers and other pipes.

The billet for the manufacture of pipes, depending on the production method, enters the workshop either in the form of a faceted cast ingot or an ingot in the form of a truncated cone, a solid rolled rod of a round or square section, a hollow cylindrical blank made by centrifugal casting, or in the form of strips and sheets.

Welded pipes are obtained from strip and sheet blanks, blanks of all other listed types are intended for the manufacture of seamless pipes.

To obtain pipes from high-alloy low-ductility steels in Lately hollow cylindrical blanks are used as blanks. This eliminates the labor-intensive and sometimes impossible operation of piercing the workpiece (obtaining a hollow workpiece from a workpiece with a solid section) from these steels.

Some tube mills use ingots with a square or polyhedral section.

Solid cylindrical ingots are used in the production of finished pipes by pressing.

Round rolled blanks, as a rule, are used in the production of pipes with a diameter of less than 140 mm . Some plants produce pipes with a diameter of more than 140 mm from a round rolled billet, maximum diameter which at the same time reaches 320-350 mm.

For the manufacture of welded pipes with a diameter of up to 520 mm hot-rolled (strip), hot-rolled pickled and cold-rolled strips are used in various installations.

On mills of modern design, the strip is fed in the form of rolls different weight depending on the length of the tape in the roll and the dimensions of the produced pipes. On some installations, a strip with beveled edges is used to obtain a high-quality weld.

Pipes with a diameter of more than 520 mm are welded from individual sheets of hot-rolled steel.

In the metal supplied for the manufacture of pipes, various defects are sometimes observed, often associated with the technology of its production: non-metallic inclusions in various types of blanks, shrinkage cavities, bubbles, cracks in ingots; captivity and burrs on rolled blanks; tears, delaminations and distorted sheet sizes, etc.

These defects can affect the quality of the resulting pipes. Therefore, careful preliminary inspection, repair and rejection of metal contribute greatly to the production of high-quality steel pipes.

The methods used to detect internal defects in the workpiece (non-metallic inclusions, shrinkage cavities, bubbles, etc.) are provided for in the technical conditions for the supply of the workpiece.

production of high quality steel pipes.

4.5. Technology for the production of pipes, bends and cylinders

The technology for the production of pipe products is considered on the example of the organization of production at OAO Pervouralsky Novotrubny Plant.

Technology of production of hot-rolled pipes

Raw materials for the production of hot-rolled pipes in the form of round rods come from metallurgical plants.

Hot-rolled pipes are shipped to end users, and are also used as blanks for cold processing (production of cold-formed pipes).

For the production of seamless hot-rolled tubes, the plant uses two tube rolling machines on a short mandrel (Stiefel type), one machine for rolling tubes on a long mandrel in a three-roll stand (Assel type), and one continuous mill with tube rolling on a long movable mandrel. .

On fig. 1 shows the technological process of the mill 30-102, which manufactures pipes with a diameter of 32-108 mm with a wall thickness of 2.9 to 8 mm. The capacity of the unit is 715 thousand tons of pipes per year.

Rice. 1. Production process of hot rolled pipes

The technological process of manufacturing pipes on a unit with a continuous mill consists of the following operations:

• preparing the billet for rolling;
• heating the workpiece;
• piercing blanks into sleeves;
• rolling sleeves into pipes on a continuous mill;
• heating pipes before calibration or reduction;
• rolling pipes on a sizing or reduction mill;
• pipe cutting;
• cooling pipes and their finishing.

The main advantage of the unit is its high performance and high quality pipes. The presence in the composition of the mill "30-102" of a modern reduction mill, working with tension, significantly expands the range of rolled pipes, both in diameter and in wall thickness.

On a continuous mill, rough pipes of one constant size are rolled, which are then brought to the dimensions determined by orders on a sizing or reduction mill.

The workpiece is heated in two 3-strand sectional furnaces, each about 88 meters long. The heating part of the sectional furnace is divided into 50 sections; they, in turn, are divided into 8 zones. The temperature regime in each zone is maintained automatically.

The correctness of the heating of the metal is controlled by a photoelectric pyrometer, which measures the temperature of the sleeve coming out of the rolls of the piercing mill. The cutting of the workpiece heated in the furnace is carried out on cantilever-type shears with a lower cut. The piercing of a heated and centered workpiece is carried out on a 2-roll piercing mill with barrel-shaped rolls and axial output.

Rolling pipes in a continuous mill. The name of the mill means the continuity of the process and the simultaneous presence of the processed metal in several stands. A long cylindrical mandrel a is inserted into the sleeve obtained after rolling on a piercing mill, after which it, together with the mandrel, is sent into the rolls of a continuous mill. The mill consists of 9 stands of the same design, located at an angle of 45 degrees to the floor plane and 90 degrees to each other. Each stand has two rolls with round calibers.

After removing the long mandrel from the pipe, they are sent to a 12-stand sizing mill to obtain a diameter within the specified limits, or to a 24-stand reduction mill to roll pipes to lower diameters.

Before calibration or reduction, the pipes are heated in preheating induction furnaces. From the calibration table, pipes with a diameter of 76 to 108 mm are obtained, after a reduction table - from 32 to 76 mm.

Each stand of both mills has three rolls located at an angle of 120 degrees

in relation to each other.

Pipes rolled on a sizing mill and having a length of more than 24 meters are cut in half on a stationary circular saw. After rolling on the reduction mill, the pipes are cut with flying shears into lengths from 12.5 to 24.0 meters. In order to eliminate curvature and reduce the ovality of the cross section of the pipe, after cooling, they are straightened on a cross-roller straightening mill.

Pipes after straightening are subjected to cutting into measured lengths.

Pipe finishing is carried out on production lines, which include: pipe cutting machines, pipe trimming machines, a purge chamber for removing chips and scale, and an inspection table for Quality Control Department.

Technology for the production of cold-formed pipes

Cold-formed pipes are made from hot-rolled billet (hot-rolled pipe own production), subjected, if necessary, to mechanical boring and turning. Rolling is carried out in warm or cold mode using technological lubricants.

For the manufacture of cold-formed pipes with a diameter of 0.2 to 180 mm with a wall thickness of 0.05 to 12 mm from carbon, alloyed and high-alloyed steels and alloys, the plant uses 76 cold rolling mills, 33 pipe drawing mills and 41 cold rolling mills for pipes with rollers, coil and long mandrel mills. drawing. Production lines for coiled drawing of extra thick-walled pipes for fuel lines of diesel engines are in operation, finned pipes for boilers of superheaters of thermal power plants, profiled seamless and electric-welded cold-formed pipes of various shapes are manufactured.

The high quality of pipes is ensured by the use of heat treatment in a protective atmosphere, as well as grinding and electropolishing of the inner and outer surfaces.

On fig. 2 shows the technological processes used in the manufacture of cold-formed pipes.

Fig.2. Production process of cold-formed pipes

The technology for manufacturing pipes in pipe drawing shops has the following general sections:

• preparation of blanks for production;
• cold rolling of pipes;
• cold drawing of pipes;
• combined method (rolling and drawing);
• heat treatment of finished and intermediate pipes;
• chemical treatment of finished and intermediate pipes;
• finishing;
• finished product control.

The entire billet going for inspection is preliminarily subjected to etching to remove the scale remaining on the pipes after hot rolling. Etching is carried out in the baths of the pickling department. After pickling, the pipes are sent for washing and drying.

Pipe cold rolling mills are designed for cold and warm rolling of pipes made of carbon, alloy, stainless steels and alloys. A characteristic feature and advantage of CPT mills is the ability to achieve a 30-88% reduction in the cross-sectional area of ​​pipes and an elongation ratio from 2 to 8 or more in one rolling cycle.

The designs of the HPT mills installed in the workshops of the plant are diverse and differ from each other in standard sizes, the number of simultaneously rolled pipes and modifications.

The drawing process (only cold drawing of pipes is used at the plant) consists in passing (pulling) a billet pipe through a drawing ring, the diameter of which is smaller than the diameter of the billet.

Technological lubricant (its composition varies depending on the drawing method) is applied to the pipes to reduce the coefficient of friction during drawing.

The plant also uses pipe drawing on drums.

All pipes after drawing (drawn to the finished size or intermediate), as a rule, are subjected to heat treatment in continuous muffle or roller furnaces. The exception is some types of pipes, which are delivered without heat treatment.

Heat-treated pipes are straightened: preliminary on cam straightening presses and roller straightening machines and final - on roll-straightening mills.

Cutting the ends of pipes with deburring and cutting out the measure is carried out on pipe cutters with cutting or abrasive wheels. For complete removal of burrs in a number of workshops use steel brushes.

The pipes that have passed all the finishing operations are presented for inspection to the quality control inspection tables.

Production technology of electric-welded pipes

For the production of straight-seam electric-welded pipes with a diameter of 4 to 114.3, the plant has 5 electric welding mills. In the manufacture of pipes from carbon steels, the method of high-frequency welding is used, from high-alloy steels - arc welding in an inert gas environment. These technologies, combined with physical methods of control and hydraulic tests ensure the reliability of pipes when used in mechanical engineering and building structures.

Removal of internal burr, high purity of the inner surface of the pipes allow to obtain high quality products. Additionally, welded pipes can be subjected to mandrel and mandrelless drawing and rolling on roller mills. Heat treatment in a protective atmosphere furnace ensures a bright tube surface.

The factory uses the most modern technology welding - high frequency currents (radio frequency). The main advantages of this pipe welding method:

• the possibility of achieving high welding speed;
• obtaining pipes with a high-quality seam from a hot-rolled non-etched billet;
• relatively low power consumption per 1 ton of finished pipes;
• the possibility of using the same welding equipment when welding various low-alloy steel grades.

The principle of the method is as follows: a high-frequency current, passing near the edges of the tape, intensely heats them up, and when they come into contact in the welding unit, they are welded due to the appearance of a crystal lattice. An important advantage of the high-frequency welding method is that the microhardness of the weld and the transition zone differs by only 10–15% from the microhardness of the base metal. Such a structure and properties of a welded joint cannot be obtained by any of the existing pipe welding methods.

On fig. 3 shows the technological process for the production of electric-welded pipes for household refrigerators.

Fig.3. Production process of electric welded pipes

The raw material for the production of electric-welded pipes is strips (sheet metal rolled into rolls) coming from metallurgical plants. The blank comes in rolls with a width of 500 to 1250 mm, and for the production of pipes, a tape with a width of 34.5 - 358 mm is required, i.e. the roll must be cut into narrow strips. For this purpose, a slitting unit is used.

The docked strip is fed by pulling rollers into the drum strip accumulator to ensure a continuous technological process due to the created strip stock. From the accumulator, the tape enters the forming mill, which consists of 7 stands with two rolls in each. Between each stand there is a pair of vertical (edge) rolls to stabilize the movement of the tape. The forming machine is designed for cold forming the strip into an endless billet.

molded (but with open slit between the edges) the pipe enters the welding unit of the mill, where the edges are welded with high-frequency currents. Part of the metal, due to the pressure of the welding unit, protrudes both inside the pipe and outside in the form of a flash.

After welding and removal of the outer flash, the pipe is guided along the roller table, which is in a closed chute, to the calibration and profiling unit, while it is abundantly watered with a cooling emulsion. The cooling process continues both in the sizing and profiling mill and when cutting the pipe with a flying circular saw.

Calibration of round pipes is carried out in a 4-stand sizing mill. Each stand has two horizontal rolls, and vertical rolls are installed between the stands, also two each.

Profiling of square and rectangular pipes is carried out in four 4-roll stands of the profiling section.

Electric-welded pipes for household refrigerators additionally after profiling undergo high-frequency annealing, cooling and then enter the galvanizing bath for coating with an anti-corrosion coating.

The composition of the finishing equipment for electric-welded pipes includes: a face machine with two face heads for processing the ends of pipes; hydraulic press for testing pipes, if it is prescribed by regulatory documentation; tubs for pneumatic testing of pipes for refrigerators.

Production technology of pipes lined with polyethylene

Steel pipes lined with polyethylene and connecting parts of pipelines (bends, tees, transitions) are designed to move aggressive media, water and oil under pressure up to 2.5 MPa and are used in the chemical and oil refining industries.

The maximum operating temperature of lined pipes is + (plus) 70°С, the minimum installation temperature for pipes with flanges is 0°С, for flangeless connections - (minus) 40°С.

The plant produces a set of steel, polyethylene-lined pipelines with flange connections ready for installation, which include: lined pipes, equal and transition tees, concentric transitions and bends.

Lined pipes can be with internal, external and double (inside and outside) lining. Lined pipes are distinguished by the strength of steel and the high corrosion resistance of plastics, which allows them to effectively replace pipes made of high-alloy steel or non-ferrous metals.

As a lining layer, low-pressure polyethylene (high density) of pipe grades is used, which protects the metal both from internal corrosion due to the impact of transported products, and from external corrosion - soil or air.

On fig. 4 shows the technological processes used in the manufacture of pipes lined with polyethylene.

Polyethylene pipes are produced by continuous screw extrusion on lines with worm drives.

Before lining, steel pipes are cut to lengths corresponding to the specifications of pipelines. Threads are cut at the ends of the pipes, threaded stop rings are screwed on and loose flanges are put on.

Pipes intended for connection into pipelines without flanges (oil and gas fields, water pipes) are cut to cut lengths, pipe ends are machined, chamfers are removed.

The lining of steel pipes is carried out by the method of joint drawing or by the tightening method. The tees are lined with injection molding.

Pipes with flanges are lined from the inside, without flanges - from the inside, outside or on both sides.

After lining at the ends of the pipes of the flange connection, the lining layer is flanged onto the ends of the threaded rings.

Tees and concentric reducers are lined by plastic injection molding on injection molding machines. Bent bends are made from short lined pipes on pipe bending machines. Cases of sector bends are lined with polyethylene pipes with subsequent flanging of the ends onto the flanges.

Fig.3. Production process of pipes lined with polyethylene

Branch production technology

Steeply curved seamless welded bends in accordance with GOST 17375-83 and TU 14-159-283-2001 are designed for transportation of non-aggressive and medium-aggressive media, steam and hot water at conditional pressure up to 10 MPa (100 kgf/cm2) and temperature range from minus 70° C to plus 450° C.

Outer diameter: 45 - 219 mm, wall thickness: 2.5 - 8 mm, bending angle: 30°, 45°, 60°, 90°, 180°, steel grade: 20, 09G2S, 12Kh18N10T.

For the production of bends, a modern energy-saving and environmentally friendly technology was chosen, which gives the best indicators of the quality of the finished product, both in terms of dimensional characteristics and mechanical properties.

The main equipment is presses for hot broaching of tubular blanks along a horn-shaped core using induction heating.

According to the general quality strategy of Novotrubny Zavod, bends are made only from profiled pipes using a full cycle of monitoring the properties of finished products. Compliance of products with the accepted normative and technical documentation is confirmed by 100% verification of dimensional characteristics and laboratory tests. Permissions and certificates of supervisory authorities have been obtained for the production of parts, confirming the suitability of our products for use in highly aggressive environments, including at facilities supervised by the Gosgortekhnadzor of Russia.

On fig. 4 shows the technological processes used in the manufacture of bends.

Rice. 5. Elbow production process

The technology for the production of bends includes the following stages:

• cutting into measured blanks (pipes) of pipes obtained from the pipe shops of the plant and having passed the appropriate output quality control;
• hot broach of branch pipes on a horn-shaped core. Broach is carried out on special hydraulic presses using graphite-based lubricants;
• hot volume straightening of bends in vertical hydraulic presses (calibration). When this occurs, the editing of geometric dimensions, primarily diameters;
• preliminary flame or plasma trimming of the allowance for uneven ends of the branches;
• mechanical processing of the ends of the bends and chamfering (trimming);
• acceptance by OTC:

—control of geometric dimensions,

—hydrotesting,

—laboratory testing of the mechanical properties of a batch of bends,

—marking.

5. Quality issues of pipe products

1. 1. What types of control are provided for by regulatory documentation?

Answer: Any regulatory documentation (GOSTs, TUs, specifications) necessarily provides for the following types of pipe inspection:

• quality control of the outer surface;
• quality control of the inner surface;
• control of geometric parameters: outer and 9 or) inner diameter, wall thickness, curvature, perpendicularity of the ends to the axis of the pipe, length, chamfer width (where measured in accordance with regulatory and technical documentation), thread sizes (for threaded pipes).

1. 2. What are the requirements for pipes before starting inspection?

Answer:

• pipes must have a working label;
• pipe surfaces must be dry and clean;
• pipes should lie on the inspection table in the inspection area in one row with an interval depending on the diameter, allowing them to move freely (tilt around their axis) to inspect the entire surface, and not just in a certain area.
• Pipes must be straight, i.e. roll freely on the rack, have evenly cut ends and remove burrs.

Note: In some cases, uncut ends are allowed by customers, and permission is given for the absence of pipe straightening.

1. 3. How is visual inspection of the outer surface of pipes performed?

Answer: Produced directly on inspection tables (racks) by inspectors with normal vision without the use of magnifiers. Inspection of the surface is carried out in sections, followed by re-edging of each pipe so that the entire surface is inspected. Simultaneous control of several pipes at once is allowed; it should be remembered that the total inspection surface does not exceed the angle of view. In doubtful cases, i.e. when the defect is not clearly defined. The inspector is allowed to use a file or sandpaper, with which he cleans the surface of the pipe.

1. 4. How to estimate the depth of an external defect if it is in the middle of the pipe length?

Answer: If it is necessary to determine the depth of the defect, a control filing is made, followed by a comparison of the pipe diameter before and after the defect is removed:

1. 1. The diameter is measuredDnext to the defect
2. 2. The minimum diameter is measured at the defect site, i.e. maximum defect depth;
3. 3. The wall thickness is measuredSalong the generatrix of the defect;
4. 4. Depth of defect:D— dcompared (with allowance for tolerances) with the actual wall thickness.

To determine the nature of the defect, it is compared with defect samples (standards) approved in the proper manner.

1. 5. Why and how is instrumental control of the outer surface of pipes used?

Answer: Instrumental control is used to assess the quality of the outer surface of pipes for critical purposes: boiler rooms, for aviation equipment, nuclear energy, ball bearing plants, etc.

Devices for such control are installations of ultrasonic, magnetic or eddy current testing.

1. 6. How to make a visual inspection of the inner surface of the pipes?

Answer: The essence of this control method is that a light bulb on a long holder is inserted into each pipe, which has a sufficiently large internal channel, from the side opposite from the controller, with the help of which it can move along the pipe and illuminate doubtful places. For smaller sizes (in pipe drawing shops), so-called screens are used - backlights, consisting of a number of "daylight" lamps and giving even light.

1. 7. Why and how is instrumental control of the inner surface of pipes used?

Answer: It is used for responsible pipes. It is subdivided into instrumental control and control with the help of periscopes according to a special technique, with an increase in the area of ​​the controlled surface by 4 times. To determine the nature and depth of the defect of the inner surface, a dubious section of the pipe can be cut out for additional control (for example, on a microscope) and conclusion.

The control of pipes with a small internal section is carried out with the naked eye or with the use of magnification on samples cut along the generatrix of the pipe ("boat").

8. How is the manual measurement of pipe wall thickness performed?

Answer: The wall thickness is checked at both ends of the pipe. The measurement is made with a pipe micrometer of the MT 0-25 type of the second accuracy class at least at two diametrically opposite points. In case of detection of wall difference or maximum allowable values, the number of measurements increases.

1. 8. How is the manual control of the outer diameter of the pipes?

Answer: Manually, the outer diameter of the pipes is controlled using a smooth micrometer of the MK type of the second class, or with calibrated brackets in at least two sections. In each section, at least two measurements are made at an angle of 90 ° one to the other, i.e. in mutually perpendicular planes. In case of detection of marriage or maximum permissible values, the number of sections and measurements increases.

1. 9. Why and how is instrumental control of the outer diameter of pipes used? Examples.

Answer: It is used for critical pipes and is carried out simultaneously with the control of surface continuity, wall thickness on UKK-2 devices, R RA. On roller cold rolling mills (HPTR) for technological control of the diameter of pipes, a CED device (compact electromagnetic diameter meter) is used.

10. How is the manual control of the inner diameter of pipes carried out? Examples.

Answer: It is produced in accordance with orders using a certified caliber (for sizes from 40 mm and more, the common name is “rolling pin”) of the “pass - no-pass” type for a length specified by regulatory documentation at both ends of the pipe. For example, for pumping and compressor pipes according to GOST 633-80, straightness control from each end is required by 1250 mm; while simultaneously monitoring the inner diameter. To control the inner diameter of pipes used for the manufacture of shock absorbers, where high dimensional accuracy is required, special instruments are used - bore gauges.

11. When is instrumental control of the inner diameter of pipes necessary? Examples.

Answer: It is used only for critical pipes and is produced on devicesRPAand UKK - 2, for example, in the production of stainless pipes.

12. How is the curvature (straightness) of pipes controlled? Examples.

Answer: The straightness of pipes, as a rule, is ensured by the production technology and, in practice, is checked “by eye”. In doubtful cases, or on request normative documentation, the actual curvature is measured. It is carried out on any one measuring section or along the entire length of the pipe - depending on the requirements of regulatory documentation. Curvature measurement requires a flat horizontal surface (ideally a surface plate). A measured area is selected with the maximum “by eye” curvature; if the curvature is in the same plane with the slab, a straightedge 1 meter long, type ShchD, second accuracy class, is superimposed on the side and using a set of probes No. 4, the gap between the pipe and the ruler is checked.

13. In what cases and how is chamfer blunting controlled?

Answer: produced at the request of regulatory documentation using a measuring ruler or template. The control of the chamfer angle is carried out at the request of regulatory documentation using a goniometer.

14. When and how is the perpendicularity of the pipe end to its axis checked?

Answer: A metal square is used. The short side of the elbow is applied along the generatrix of the pipe. long side the square is pressed against the end of the pipe in 2 - 3 sections. The presence of the gap and its value is checked with a feeler gauge.

15. How is pipe length measured manually?

Answer: it is carried out by two workers by applying a measuring tape of a metal RS-10 or plastic tape along the generatrix of the measured pipe.

16. Methods for determining steel grades.

Answer: control of steel grades is carried out by the following methods:

• sparking;
• steeloscopy;
• chemical or spectral analysis.

6. Issues of classification of types of defects in the manufacture of pipes and ways to correct them

1. 1. What are the main categories of marriage, identified in the process of production and control of finished products?

Answer: The adopted quality accounting system divides the defects identified during the control of finished products into two categories: defects due to the fault of steelmaking and steel-rolling production and defects of pipe-rolling production (this includes defects on cold-formed and welded pipes).

1. 2. Types and causes of defective steel production, affecting the quality in the manufacture of pipes.

Answer:

• A shrinkage cavity, open and closed, is a cavity formed during the hardening of the metal after it has been poured into molds. The reason for this defect may be a violation of the technology of pouring steel, the shape of the mold, the composition of the steel. The most advanced method of dealing with shrinkage cavities is continuous casting of steel.
• Liquidation in steel. Segregation is a heterogeneity of steel and alloys in composition, which is formed during their solidification. An example of segregation is a segregation square, which is revealed in transverse macrosections of metal and represents a structural heterogeneity in the form of differently etched zones, the contours of which repeat the shape of an ingot. The reasons for the segregation square can be an increased content of impurities (phosphorus, oxygen, sulfur), a violation of the technology of casting or solidification of the ingot, the chemical composition of the steel (for example, with a wide temperature limit of solidification). Reducing the segregation square is achieved by reducing impurities, lowering the steel casting temperature and reducing the mass of ingots.
• internal bubbles. They are cavities formed as a result of the release of gases during the crystallization of the ingot. The most common cause of bubbles is the high concentration of oxygen in the liquid metal. Measures to prevent bubbles: complete deoxidation of the metal, the use of well-dried materials for alloying and slag formation, drying of tundish devices, cleaning molds from scale.
• Honeycomb. These are gas bubbles located in the form of honeycombs at a very small distance from the surface of an ingot of boiling or semi-quiet steel. Lead to delamination of steel. Possible reasons for their appearance can be high rates of steel casting, increased gas saturation, overoxidation of the melt.
• Axial porosity. The presence in the axial zone of the ingot of small pores of shrinkage origin. It occurs when the last portions of liquid metal solidify under conditions of insufficient supply of liquid metal. The reduction of axial porosity is achieved by pouring steel into molds with a large taper, as well as by insulating or heating the hot part.
• Inversions of crusts. A defect is a wrapped metal crust and splashes located near the surface of the ingots, affecting part or all of the ingot. On the microsection in the defect zone there are large accumulations of non-metallic inclusions, decarburization and scale are often observed. Inversions of crusts, floods, splashes can occur in the metal of all steel grades with any casting methods. Reasons: pouring cold metal, slow pouring speed, and pouring metal with high viscosity. An effective means of preventing a defect is pouring under liquid synthetic slag.
• Volosovina. The defect is expressed in the form of thin, sharp scratches of different depths caused by contamination of the surface of the ingot or pipe billet with non-metallic inclusions (slags, refractories, insulating mixtures). Surface defects are well detected on a turned or pickled pipe billet, as well as when descaled finished pipes. Prevention measures: the use of high-quality refractories, holding metal in ladles, pouring under liquid slag, various refining remelts.

1. 3. Types and causes of defective steel-rolling production, affecting the quality in the manufacture of pipes?

Answer:

• Internal breaks during deformation. They are formed during hot deformation (rolling) in the axial zone of blooms or tubular billets due to its overheating. Axial overheating fractures are most common in high carbon and high alloy steels. It is possible to prevent the formation of a defect by lowering the heating temperature of the metal before deformation or by reducing the degree of deformation in one pass.
• Birdhouse. It is an internal transverse thermal crack opened during rolling in an ingot or billet. The cause of the defect is a sharp heating of a cold ingot or billet, in which the outer layers of the metal heat up faster than the inner ones, and stresses arise that lead to metal rupture. The most prone to the formation of birdhouses are high-carbon steels U7 - U12 and some alloyed steels (ShKh - 15, 30KhGSA, 37KhNZA, etc.). Measures to prevent a defect - compliance with the technology of heating ingots and billets before rolling.
• Flaws. These are open fractures located at an angle or perpendicular to the direction of the greatest stretching of the metal, formed during hot deformation of the metal due to its reduced plasticity. Rolling of a pipe billet from blooms with flaws leads to the appearance of rolling films on the surface of the rods. The reasons for the appearance of flaws can also be violations of the metal heating technology and high degrees of compression. Blanks with flaws are carefully cleaned.
• Steel captivity. This term refers to defects in the form of delamination of metal of various shapes, connected to the base metal. The lower surface of the captive is oxidized, and the metal underneath is covered with scale. The causes of steel-smelting captivity can be the rolling of defects in the ingot of steel-smelting origin: inversions of crusts, accumulations of subcrustal and surface gas bubbles, longitudinal and transverse cracks, sagging, etc. Measures to prevent steelmaking captivity: compliance with the technology of smelting and pouring steel.

1. 4. Methods for detecting surface and internal metal defects.

Answer: In modern practice, the following main methods for detecting and studying surface and internal metal defects are used:

• external inspection of the product;
• ultrasonic testing to detect internal defects;
• electromagnetic control methods for detecting surface defects;
• local cleaning of the surface;
• upsetting of specimens cut from bars for a clearer detection of surface defects;
• stepwise turning of bars to reveal hairs;
• macrostructure studies on transverse and longitudinal templates after etching;
• study of longitudinal and transverse fractures;
• electron-microscopic research methods;
• study of unetched microsections (to assess contamination with non-metallic inclusions);
• study of the microstructure after etching to identify structural components;
• x-ray diffraction analysis.

1. 5. Types and causes of defects in the manufacture of pipes by hot rolling. Marriage repair.

Answer:

• Rolling captivity. Longitudinal orientation defect. The reason is the rolling of defects in the surface of the pipe billet or bloom in the pipe: trimming, seaming, mustache, zakov, wrinkles. External captives are not subject to repair and are the final marriage.
• Flocks. They are thin breaks in the metal formed due to structural stresses in steel saturated with hydrogen. They usually appear in rolled metal, are detected by ultrasonic testing. Flocks appear in the process of cooling the metal at a temperature of 250 ° C and below. They are found mainly in structural, tool and bearing steels. Measures to prevent flocs: vacuum-arc remelting.
• Cracks. During the formation of an ingot and its subsequent deformation, a number of defects in the form of cracks are encountered in practice: hot cracks, stress cracks, pickling cracks, etc. Consider the most characteristic - hot cracks.

A hot crystallization crack is an oxidized metal fracture formed during the crystallization of an ingot due to tensile stresses exceeding the strength of the outer layers of the ingot. Rolled hot cracks can be oriented along the rolling axis, at an angle to it, or perpendicularly, depending on the location and shape of the initial defect in the ingot. Of the factors that cause cracking, one can name: overheating of the liquid metal, increased casting speed, increased sulfur content, as the ductility of steel decreases, violation of the steel casting technology, and the influence of the steel grade itself. Cracks cannot be repaired and are the final marriage.

• Stratification. This is a violation of the continuity of the metal, caused by the presence in the original ingot of a deep shrinkage cavity, shrinkage looseness or accumulation of bubbles, which, upon subsequent deformation, comes to the surface or end edges of the product. Prevention measures: reduction of harmful impurities in the metal, reduction of gas saturation, use of additives, compliance with the technology of smelting and casting steel. Bundles are not subject to repair and are the final marriage.
• Sunset. This is a violation of the continuity of the metal in the direction of rolling from one or both sides of the product (pipe) along its entire length or along its part as a result of rolling the mustache, undercutting or rolling from the previous caliber. The reason for the sunset is usually the overflow of the working caliber with metal, when it (the metal) is “squeezed out” into the space between the calibers in the form of a mustache, and then rolled up. Prevention measures: correct calibration of the tool, observance of rolling technology. It cannot be repaired and is a final marriage.
• Shells. Surface defect, which is local depressions without discontinuity of the pipe metal, which were formed from the loss of local captives, non-metallic inclusions, rolled-in objects. Prevention measures: use of high-quality pipe blanks, observance of rolling technology.
• Sold Surface defect, which is a through hole with thinned edges, elongated in the direction of deformation. The causes of the defect are the ingress of foreign bodies between the deforming tool and the pipe.
• Cracks of pipe-rolling origin. A surface defect of longitudinal orientation, which is a discontinuity of the metal in the form of a narrow gap, which usually goes deep into the wall at a right angle to the surface. Causes: reduction of sub-cooled pipes, excessive deformation during rolling or straightening, the presence of residual stresses in the metal that were not removed by heat treatment. Prevention measures: compliance with pipe production technology. Final marriage.
• Internal captivity. The reason for internal captivity is the premature opening of the cavity in the core of the workpiece before flashing. The appearance of internal films is greatly influenced by the plasticity and toughness of the pierced metal. To prevent captivity on cold-formed pipes, the pipe blank is subjected to boring on pipe boring machines.
• Dents. Surface defect, which is a local depression without breaking the continuity of the metal. A variety of dents are tool marks.
• Screw trace. A surface defect, which is periodically repeated sharp protrusions and ring-shaped depressions located along a helical line. Cause: Incorrect setting of the piercing mill lines or break-in machines. Prevention measures: compliance with the technology of production and finishing of pipes.

1. 6. Types and causes of defects in the manufacture of cold-formed pipes. Ways to mend a marriage.

Answer:

• Birdhouse. A surface defect that is oblique, often at an angle of 45° , breaks in metal of various depths up to through. It is more common on high-carbon and alloyed cold-formed pipes. Causes: excessive deformation, which caused excessive additional stresses; insufficient metal ductility due to poor-quality intermediate heat treatment of pipes. Prevention measures: correct calibration of the working tool, compliance with pipe production technology. They are not subject to repair, they are the final marriage.
• Scale. Formed at heat treatment pipes, degrades the quality of pipe surfaces and interferes with inspection. When straightening pipes that have undergone heat treatment, part of the scale is mechanically removed, and part remains, converting it into marriage. Preventive measures: Heat treatment in protective atmosphere furnaces, pickling or machining of pipes.
• Squeeze. It is most often encountered in mandrelless drawing of cold-formed pipes. Cause: loss of stability of the pipe cross-section during rolling, excessive deformations, metal overfilling of the drawing ring due to incorrect calibration.
• Risks and bullying. Risks - recesses on the outer or inner surfaces of the pipe, without changing the continuity of the metal. Bully - differs from risks in that part of the metal of the pipe is mechanically torn off and collected along the axis of the pipe into chips, which can then fall off. Cause: Poor preparation of the drawing tool, ingress of foreign particles between the tool and the pipe, low mechanical characteristics pipe metal. Prevention measures: compliance with pipe production technology.
• Internal annular prints and gaps (trumpet flutter). Reason: poor quality coating before drawing, low metal ductility, high drawing speed. Prevention measures: compliance with pipe production technology.
• rowanberry. Minor irregularities of various shapes, located on the entire surface of the pipe or part of it. Causes: Poor surface preparation for rolling and drawing, increased wear of rolling tools, poor lubrication, dirty pickling baths, poor processing at intermediate stages of production. Prevention measures: compliance with pipe production technology.
• Overtreated Surface defect in the form of point or contour depressions located in separate sections or over the entire surface of the pipes, representing local or general damage to the metal surface during pickling. Not subject to repair.
• Penetration. Surface defect, characteristic only for the contact method of electrochemical polishing. Causes of penetration on the outer surface: high current density and poor contact of the current-carrying brush with the pipe surface. Penetration on the inner surface is a consequence of poor insulation of the cathode rod, wear of insulators on the cathode, small interelectrode distance, and large curvature of the cathode rod. Prevention measures: compliance with the technology of electrochemical polishing of pipes. Not subject to repair.

1. 7. Types and causes of defects in the manufacture of welded pipes. Measures to prevent marriage.

Answer:

• Offset of the edges of the tape during welding. It is the most characteristic type of defect in the production of electric-welded pipes. The reasons for this defect are: misalignment of the axis of the forming mill rolls in the vertical plane; incorrect setting of the rolls; asymmetric position of the tape relative to the axis of molding and welding; welder malfunction.
• Lack of fusion This type of marriage, when the seam of the welded pipe is either extremely weak, or completely remains open, i.e. the edges of the tape do not converge and are not welded. The reasons for lack of penetration can be: a narrow tape; discrepancy between the welding speed and the heating mode (the speed is high, the current strength is low); offset edges of the tape; insufficient reduction in welding rolls; failure of the ferrite set.
• Burns. Defects under this name are located on the surface of the pipe near the welding line, both on one side of the weld, and on both sides. The causes of arson are: high arc power, resulting in overheating of the tape edges; damage to the insulation of the inductor; poor-quality tape preparation.
• External and internal grate. Burr is a metal squeezed out of the seam during compression of the edges of the tape, its appearance is technologically inevitable. Specifications the complete absence of a grate is provided. Its presence indicates the incorrect installation of the deburring cutter, its blunting.

1. 8. What types of marriage cannot be repaired and why?

Answer: Rolled captivity, cracks of pipe-rolling origin, cracks, delamination, sunsets, birdhouses, overcuts, penetrations are not subject to repair and are the final marriage.

Metallurgical enterprises of Russia

7.1. Metallurgical plants

1. 1. OJSC "West Siberian Metallurgical Plant" - Novokuznetsk: a circle of carbon steel grades, a circle of alloyed steel grades, a circle of stainless steel grades.
2. 2. JSC "Zlatoust Iron and Steel Works" - Zlatoust: a circle of carbon steel grades, a circle of alloyed steel grades, a circle of stainless steel grades.
3. 3. JSC "Izhstal" - Izhevsk: a circle of stainless steel grades.
4. 4. JSC "Kuznetsk Iron and Steel Works" - Novokuznetsk: a circle of carbon steel grades.
5. 5. OJSC "Magnitogorsk Iron and Steel Works" - Magnitogorsk: strip, circle of carbon steel grades.
6. 6. JSC Metallurgical Plant Krasny Oktyabr - Volgograd: a circle of carbon steel grades, a circle of alloyed steel grades, a circle of ball-bearing steel grades, a circle of stainless steel grades.
7. 7. OAO Metallurgical Plant Elektrostal - Elektrostal: strip, circle made of stainless steel grades.
8. 8. OAO Nizhny Tagil Metallurgical Plant - Nizhny Tagil: a circle of carbon steel grades.
9. 9. OJSC "Novolipetsk Iron and Steel Works" - Lipetsk: strip.

10. OAO Orsk-Khalilovsky Metallurgical Plant - Novotroitsk: strips, a circle of carbon steel grades, a circle of low-alloy steel grades.

11. JSC "Oskol Electro-metallurgical Plant" - Stary Oskol: a circle of carbon steel grades.

12. JSC "Severstal" (Cherepovets Metallurgical Plant) - Cherepovets: strip, circle of carbon steel grades.

13. JSC Serov Metallurgical Plant - Serov: a circle of carbon steel grades, a circle of alloyed steel grades, a circle of ball-bearing steel grades.

14. JSC "Chelyabinsk Metallurgical Plant" - Chelyabinsk: stainless steel strip, circle of carbon steel grades, circle of alloyed steel grades, circle of ball-bearing steel grades, circle of stainless steel grades.

7.2. Pipe plants and their brief description

JSC "Pervouralsk Novotrubny Plant" (PNTZ)

It is located in the city of Pervouralsk, Sverdlovsk Region.

Produced assortment:

— water and gas pipes according to GOST 3262-75 with a diameter of 10 to 100 mm;

— seamless pipes according to GOST 8731-80 with a diameter of 42 to 219 mm;

— seamless cold-formed pipes according to GOST 8734 and TU 14-3-474 with diameters from 6 to 76 mm.

— electric-welded pipes in accordance with GOST 10704 with a diameter of 12 to 114 mm.

PNTZ also manufactures pipes on special orders (thin-walled, capillary, stainless steel).

OJSC Volzhsky Pipe Plant (VTZ)

Located in the city of Volzhsky, Volgograd region.

Produced assortment:

— spiral-seam pipes of large diameter from 325 to 2520 mm.

The good quality of products manufactured by VTZ determines a stable sales market, and VTZ has a monopoly in Russia for pipes with a diameter of 1420 to 2520.

OAO Volgograd Pipe Plant VEST-MD (VEST-MD)

Located in Volgograd.

Produced assortment:

—water and gas pipes according to GOST 3262-77 with a diameter of 8 to 50 mm;

—electric-welded pipes in accordance with GOST 10705-80 with a diameter of 57 to 76 mm.

VEST-MD is simultaneously engaged in the production of capillary and thin-walled pipes of small diameters.

OJSC Vyksa Metallurgical Plant (VMZ)

Located in Vyksa, Nizhny Novgorod region. Vyksa Metallurgical Plant specializes in the production of electric-welded pipes.

— 3262 diameter from 15 to 80mm.

— 10705 diameter from 57 to 108mm.

— 10706 diameter from 530 to 1020mm.

— 20295 diameter from 114 to 1020mm.

According to GOST 20295-85 and TU 14-3-1399 come with heat treatment and meet the most high requirements to quality.

OJSC Izhora Plants

Located in Kolpino, Leningrad region.

Produced assortment:

— seamless pipes in accordance with GOST 8731-75 with a diameter of 89 to 146 mm.

Also JSC Izhorskiye Zavody fulfills special orders for the manufacture of seamless thick-walled pipes.

OJSC "Seversky Pipe Plant" (STZ)

Located in the Sverdlovsk region at the station Polevskoy.

Produced assortment:

— water and gas pipes according to GOST 3262-75 with a diameter of 15 to 100 mm;

— electric-welded pipes in accordance with GOST 10705-80 with a diameter of 57 to 108 mm;

— seamless pipes according to GOST 8731-74 with a diameter of 219 to 325 mm.

— electric-welded pipes in accordance with GOST 20295-85 with a diameter of 114 to 219 mm.

Pipes of high quality from calm steel of group "B".

OAO Taganrog Metallurgical Plant (TagMet)

Located in Taganrog.

— 3262 diameter from 15 to 100mm.

— 10705 diameter from 76 to 114mm.

Seamless pipes with a diameter of 108-245 mm.

JSC "Trubostal"

It is located in St. Petersburg and is focused on the North-West region.

— water and gas pipes according to GOST 3262-75 with a diameter of 8 to 100 mm;

— electric-welded pipes in accordance with GOST 10704-80 with a diameter of 57 to 114 mm;

OAO Chelyabinsk Pipe Rolling Plant (ChTPZ)

Located in Chelyabinsk.

Produced assortment:

— seamless pipes according to GOST 8731-78 with diameters from 102 to 426 mm;

— electric-welded pipes according to GOST 10706, 20295 and TU 14-3-1698-90 with diameters from 530 to 1220 mm.

— electric-welded pipes according to GOST 10705 with diameters from 10 to 51 mm.

— water and gas pipes according to GOST 3262 with diameters from 15 to 80 mm.

In addition to the main diameters, ChTPZ is engaged in the production of galvanized water and gas pipes.

Agrisovgaz LLC (Agrisovgaz)

Located in the Kaluga region, Maloyaroslavets

OJSC Almetyevsk Pipe Plant (ATZ)

Located in the city of Almetyevsk.

JSC "Bor Pipe Plant" (BTW)

Located in the Nizhny Novgorod region, Bor.

OAO Volgorechensk Pipe Plant (VrTZ)

Located in the Kostroma region, Volgorechensk.

OAO Magnitogorsk Iron and Steel Works (MMK)

Located in Magnitogorsk.

OAO Moscow Pipe Plant FILT (FILT)

Located in Moscow.

JSC "Novosibirsk Metallurgical Plant named after V.I. Kuzmina (NMZ)

Located in Novosibirsk.

PKAOOT "Profil-Akras" (Profile-Akras)

Located in the Volgograd region, Volzhsky

OAO Severstal (Severstal)

Located in Cherepovets.

OAO Sinarsky Pipe Plant (SinTZ)

Located in the Sverdlovsk region, Kamenetsk-Uralsky.

OJSC "Ural Pipe Plant" (Uraltrubprom)

Located in the Sverdlovsk region, Pervouralsk.

OJSC Engels Pipe Plant (ETZ) Located in the Saratov Region, Engels

8. Basic norms for loading pipe rolling

8.1. Basic norms for loading rolled pipes into railway cars

Water pipe according to GOST 3262-78

Diameter from 15 to 32 mm, with walls no more than 3.5 mm.

Water pipe according to GOST 3262-78

Diameter from 32 to 50 mm, with walls no more than 4 mm.

Loading rate from 45 to 55 tons per 1 gondola car.

Water pipe according to GOST 3262-78

Diameter from 50 to 100 mm with walls no more than 5 mm.

Loading rate from 40 to 45 tons per 1 gondola car.

Welded pipe according to GOST 10704, 10705-80

Diameter from 57 to 108 mm with walls no more than 5 mm.

Loading rate from 40 to 50 tons per 1 gondola car.

Welded pipe according to GOST 10704, 10705-80

Diameter from 108 to 133 mm with walls no more than 6 mm.

Loading rate from 35 to 45 tons per 1 gondola car.

Welded pipe according to GOST 10704-80, 10705-80, 20295-80

Diameter from 133 to 168 mm with walls no more than 7 mm.

Welded pipe according to GOST 10704-80, 20295-80

Diameter from 168 to 219 mm with walls no more than 8 mm.

The loading rate is from 30 to 40 tons per 1 gondola car.

Welded pipe according to GOST 10704-80, 20295-80

Diameter from 219 to 325 mm with walls no more than 8 mm.

Welded pipe according to GOST 10704-80, 20295-80

Diameter from 325 to 530 mm with walls no more than 9 mm.

Loading rate from 25 to 35 tons per 1 gondola car.

Welded pipe according to GOST 10704-80, 20295-80

Diameter from 530 to 820 mm with walls no more than 10-12 mm.

Loading rate from 20 to 35 tons per 1 gondola car.

Welded pipe according to GOST 10704-80, 20295-80

Diameter from 820 mm with walls from 10 mm and more.

Loading rate from 15 to 25 tons per 1 gondola car.

Spiral pipe

The loading rates are similar to the loading rates of an electric-welded pipe.

Seamless pipeaccording to GOST 8731, 8732, 8734-80

Diameter from 8 to 40 mm with walls no more than 3.5 mm.

Loading rate from 55 to 65 tons per 1 gondola car.

The remaining loading rates are similar to the loading rates for an electric-welded pipe.

All norms for loading railway cars depend on tubular packaging (bags, bulk, boxes, etc.). The issue of packaging must be approached with clear calculations in order to reduce costs in rail transport.

8.2. Basic norms for loading rolled pipes into trucks

Loading rates in vehicles of the MAZ, KAMAZ, URAL, KRAZ brands with a scow (body) length of not more than 9 meters range from 10 to 15 tons, depending on the diameter of the pipe and the length of the scow (body) racks.

Loading rates in vehicles of the MAZ, KAMAZ, URAL, KRAZ brands with a scow (body) length of not more than 12 meters range from 20 to 25 tons, depending on the diameter of the pipe and the length of the scow (body) racks.

Special attention must be paid to the length of the pipe: it is not allowed to transport a pipe whose length exceeds the length of the scow (body) by more than 1 meter.

For intercity transportation, it is not allowed to load cars of all brands more than 20 tons per car. Otherwise, a large fine will be charged for overloading the axle. The fine is collected at weight control points installed on motorways by the Russian Transport Inspectorate.

Employees for less than a year, regardless of their cost, as well as items worth up to 100 times the minimum monthly wage per unit, regardless of the length of their service, and in budgetary organizations - up to 50 times its size).

Moreover, this entry is made at the actual cost, and the collection is at retail prices, and sometimes in several multiples. The difference between the cost of materials at collection prices and their actual cost is taken into account on a special off-balance sheet account. As the amounts are collected, the difference is credited to the state budget.

Taking into account the established opinion that the main distorting effect on the dynamics of production volume indicators is exerted by different material consumption of products, it could be assumed that the highest deviations of private indicators of efficiency by type of product from the general level of efficiency for the enterprise as a whole will be observed for all indicators of the efficiency of the use of materials, and especially in terms of indicators calculated on the basis of the volume products sold. In fact, at almost all the analyzed plants, the deviation of private performance indicators from the general level for the plant as a whole in terms of the use of materials turned out, as a rule, to be less than in terms of the efficiency of using fixed production assets and even labor. The difference in return (efficiency) is 1000 rubles. the cost of materials in the production of different types of products rarely reaches 2-3 times, and for the costs of production assets 4-6 times.

At machine-building plants there are special procurement workshops where materials are cut. If there are no such workshops or their organization is impractical, then a cutting department is allocated in the processing workshops. When cutting materials are of great importance correct application multiples, measured and standard sizes materials, the maximum reduction in the amount of returnable and non-returnable waste, the possible use of waste by producing smaller parts from them, preventing the consumption of full-sized materials for cutting blanks that can be produced from incomplete materials, eliminating defects during cutting.

An increase in K.r.m., and, consequently, a decrease in waste materials, is facilitated by ordering measured and multiple sizes. When cutting parts and products of various sizes and complex configurations in order to increase K, r.m. use EMM and computer technology.

The most important requirements, which must be guided by the compilation of Z.-s. and checking their correctness, are the following: a) strict compliance of the ordered quantity of products for the expanded assortment with allocated supply funds and concluded supply contracts for each position of the group nomenclature b) full compliance of the ordered assortment with current standards, technical. conditions, catalogs, as well as concluded supply contracts, while it is important to expand the use of the most progressive varieties of products, materials of measured and multiple sizes, etc. c) compliance with established norms order and the correct accounting of transit norms of deliveries d) the uniform distribution of ordered products by delivery time with its regular consumption or ensuring the timeliness of delivery with the necessary lead in relation to the terms of use (in a single shipment or construction) e) the presence and correctness of all necessary data on the consignee and payer for this order, as well as the exact indication of prices and the amount of the order, taking into account the surcharges for special conditions for its implementation.

DIMENSIONALITY AND MULTIPLICITY OF THE ORDERED MATERIALS - correspondence of the dimensions of the materials (in length and width) to the dimensions of the blanks, which must be obtained from these materials. The order of dimensional and multiple materials is done in strict accordance with the dimensional - with the estimated dimensions of a single workpiece, and the multiple - with a certain integer number of workpieces of the corresponding part or product. Dimensional materials free the consumer plant from their preliminary cutting (cutting), due to which waste and labor costs for cutting are completely eliminated. Multiple materials, when cut into blanks, can be cut without end waste (or with minimal waste), which achieves a corresponding saving in materials.

When individually cutting into blanks of the same size, the consumption rate of sheet materials or sheets cut from a roll with dimensions that are a multiple of the length and width of the dimensions of the blanks is determined as the quotient of dividing the weight of the sheet by the integer number of blanks cut from the sheet.

Table data. 4 indicate a significant differentiation in the provision of industries with the means for economic stimulation of workers. For the material incentive fund in 1980, the difference was 5-fold, and by 1985 it had decreased, despite the ordering of prices as a result of their revision from January 1, 1982, to only 3-fold. For the fund of social and cultural events and housing construction, the ratio between the minimum and maximum values ​​of these funds in 1980 was calculated per 1 ruble. wages 1 4.6, and per 1 employed - 1 5.0. In 1985, the corresponding figures were 1 3.4 and 1 4.1, respectively. At the same time, it should be noted that in such industries as the forestry, woodworking and pulp and paper industries, as well as in the building materials industry, the size of the material incentive fund was below the “sensitivity limit” for bonuses, which, according to estimates available in the literature, based on specific studies, is 10 - 15% in relation to wages.

Let the coordinates of the 1st post (xj7 y, where 1 coordinate system consider p posts and (m - p) sources. Divide the circle centered at the point (xj y () into k equal sectors so that angular dimension sector v = 360/k was a multiple of the discreteness of wind direction measurements at high-altitude meteorological stations of the Ostankino television tower, published in the annuals "Materials of high-altitude meteorological observations. Part 1". The sectors will be counted clockwise from the upper (northern) point of the circle. We will assume that the source (x, y) falls into the 1st sector 1

The supply plans developed at the enterprises reflect measures aimed at saving materials, the use of waste and secondary resources, the receipt of products of multiple and measured sizes, the necessary profiles, and a number of other measures (involving excess and unused stocks, decentralized procurement, etc. .).

Dimensional and multiple materials are widely used in organizing the supply of rolled ferrous metals for machine building and factories. The use of measured and multiple rolled products allows you to save from 5 to 15% of the weight of the metal compared to rolled products of ordinary commercial sizes. In transport engineering, this saving is even greater and varies from 10 to 25% at different plants.

When determining the feasibility of ordering materials of multiple and standard lengths, it is necessary to take into account the possibility of using end waste from cutting rods or strips of normal sizes to obtain blanks of other small parts by joint (combined) cutting of the source material. In this way, it is possible to achieve a significant increase in the utilization rate of rolled metal products without surcharges for dimensionality or multiplicity.

The current price lists (1967) for shaped rolled products, pipes, strips, etc. materials provide for the cheapest supply of materials of mixed length (with length fluctuations within known limits), the more expensive supply of precisely measured standard lengths, and finally, the most expensive supply of non-standard measured (or multiples of a given size) lengths. The rise in price varies by type of material, but the general trend is the same. In addition to increasing the cost of material and complicating the work of manufacturing plants, order specialization entails an increase in the range and number of individual delivery lots, which greatly complicates the supply and increases the size of stocks.

This item of expenditure includes almost all supplies of spare parts for the repair of equipment, Construction Materials, materials and items for current business activities, fire extinguishers, first aid kits, consumables for office equipment and computers, stationery, household chemicals, furniture, etc. These include items worth less than 50 times the minimum wage (for at the time of making the application - 5000 rubles) or a service life of less than 1 year, regardless of the cost of the item.

CUTTING PROBLEM (ut problem) - a special case of problems on the complex use of raw materials, usually solved by linear or integer programming methods. Solution 3 op helps to use blanks with minimal production waste when cutting them Statement 3 op in general view can be formulated as follows: it is required to find a minimum of a linear form, expressing the number of used sheets of material (rods, etc.) for all methods of cutting them. See also Multiple sizes of materials

DIMENSIONAL MATERIALS (pre ut materials) - materials, the dimensions of which correspond to the dimensions of the parts and blanks obtained from them. The efficiency of the order M m is complete elimination production waste during cutting due to the abolition of operations for cutting blanks For the supply of M m, the supplier charges an extra charge.

CUTTING (materials) (materials utting) - a technol process for obtaining parts and blanks from sheet materials (glass, plywood, metal, etc.) P is made taking into account the most rational use of the sheet area and minimizing production waste.

See pages where the term is mentioned Multiple sizes of materials

:             Logistics (1985) -- [

Jackson 14-02-2007 01:56

Can you recommend something budget and really working?

yogre 14-02-2007 12:19

quote: Originally posted by Jackson:
I took a Belarusian pipe with a variable magnification of 20x50, for work at the shooting range, the sellers guaranteed that at 200m I would see holes on the target from 7.62 without any problems, it turned out to be about 60m, and even then with difficulty (although the weather was cloudy).
Can you recommend something budget and really working?

Choose an increase for yourself - and try, try ....

shtift1 14-02-2007 14:54

IMHO ZRT457M, in the region of 3tyr. (100USD), it is quite efficient up to 200m., at 300 on a light background you can see from 7.62.

Jackson 14-02-2007 21:17

Thanks for the comments

stg400 15-02-2007 21:28

The issue of pipes is very complicated, you need to look in advance
to any. And the advice is this - DO NOT BUY A BUDGET PIPE WITH A VARIABLE
MULTIPLICITY. They don't know how to do things permanently.

or won't it help?

yogre 15-02-2007 21:37

I have an idea who would appreciate the "level of delusion" ..

Cut out a diaphragm from cardboard
and stick it on the lens. To improve "sharpness".
Luminosity will certainly fall. But do not throw away the pipe ..

or won't it help?

This is a way out if the main "instigator" of the loss of permission
is the lens. And this is 90% wrong. Lens with focus ~ 450 mm
already learned to count. And here it begins.....
The wrapper is a thick piece of glass in the path of the beam, which increases
black chromatism. But that's not all. Most importantly, the standard
eyepiece, the scheme of which "as unnecessary" has not been recalculated already
decades. At the same time, its focus should be in the region of 10 mm, and when
In standard schemes, this resolution "lowers" by an order of magnitude. Pro
I won't even talk about the variable multiplicity of such "masterpieces".

Serega,Alaska 16-02-2007 08:20

quote: Originally posted by yevogre:

The issue of pipes is very complicated, you need to look in advance
to any. And the advice is this - DO NOT BUY A BUDGET PIPE WITH A VARIABLE
MULTIPLICITY. They don't know how to do things permanently.
Choose an increase for yourself - and try, try ....

How is it right...
From a positive experience, I bought on eBay "e a constant 20x50 of a manufacturer NCSTAR little known to science. Such a military look, everything is in green rubber. Naturally, the pupil is 2.5mm, you won’t spoil it. But it’s small, light, with its own desktop tripod, and naturally you can see the holes , believe it or not. At 100 m without question, but in order to see at 200 m, you still need more light, it only works until early twilight. The price tag on eBay is $ 25 with delivery. I won’t say that the issue has been resolved forever, but at the very least it works from a steel concreted table at the shooting range. At the same time, the use in the field (from the hood, for example - a good field) is absolutely excluded, everything trembles to the point of complete loss of sharpness.

Only a constant in the budget (they are not so easy to find, by the way)!

Dr. Watson 16-02-2007 09:41

Burris has a good 20x trumpet.

stg400 16-02-2007 19:42

quote: Originally posted by Serega,Alaska:

little-known science manufacturer NCSTAR.

stg400 19-02-2007 07:58

the "aperture" on the lens did not help ..
throw away the pipe...

konsta 19-02-2007 23:46

Give to children. There will be some joy left.

Serega,Alaska 20-02-2007 02:10

quote: Originally posted by Serega, AK:

little-known science manufacturer NCSTAR.

quote: Originally posted by stg400:

manufacturer of optics under the state order for the carry handle of a little-known M16 rifle ...
although now there is no longer that state order ..

Or maybe it wasn't? So to say, was there a state order?

The thing is that manufacturers are deservedly proud of such things and hang information about this on all real and virtual fences. Here is AIMPOINT, for example. On his website there is a solid camouflage, SWAT, police and other offensive elements. In the red corner - Aimpoint Secures New Contract From U.S. Military - http://www.aimpoint.com/o.o.i.s/90 about how they have already sold 500,000 scopes to the army and contracted for another 163,000. And really, go buy their products. Firstly, there is very little of it on the general market, a search on eBay shows this at a time. (I have an auto search on AIMPOINT on eBay, it’s good if at least something is put up every two weeks. And the 9000L, which I’m interested in, has never been caught.) Secondly, the AIMPONT that serious dealers - noticeably more expensive than competitors, including quite decent ones (for example, Nikon RED DOT Monarch - $ 250). $ 350-450 for AIMPOINT red dot is a kind of record in this class, as well as a 10-year warranty. All this is real the status of a military contractor with a reputation.

And NcSTAR says nothing of the sort. Rastem says it's been 10 years since, since 1997, i.e. Not such an ancient story to mention the state order for their sights for the M16 capital letters if he ever was. Yes, they do something like that for the M16, but which of the owners of real M16s buys this for $50? And tons of everything from NcSTAR on eBay "e for a penny, including products for air replicas M-16, AP-15, etc. But serious dealers, as a rule, do not keep it.

I'm afraid someone misinformed you. And I, as the one who mentioned NcSTAR in a positive sense for the super-budget constant 20x50, just don’t want to attribute more to them than they deserve. Someone else gets hot, God forbid...

Thanks for attention,
Serega, AK

stg400 20-02-2007 02:31

and there is also the fake PanAmerican airline ... there are the Polaroid and Corel offices, unknown to anyone .. their shares have long been withdrawn from trading on the stock exchanges ..

so did NcStar .. made some kind of glass on the carry handle .. now it’s not in service with the M16 with them .. all flat top receivers and ACOG of another company are on them ..

Introduction date 01.01.93

1. This standard establishes a range of electric welded longitudinally welded steel pipes. 2. The dimensions of the pipes must correspond to the table. one . 3. The length of the pipe is made: random length: with a diameter of up to 30 mm - not less than 2 m; pr and diameter from v. 30 to 70 mm - not less than 3 m; with a diameter of St. 70 to 152 mm - not less than 4 m; with a diameter of St. 152 mm - not less than 5 m. At the request of the consumer, pipes of groups A and B according to GOST 10705 with a diameter of more than 152 mm are manufactured with a length of at least 10 m; pipes of all groups with a diameter of up to 70 mm - at least 4 m long; measuring length: with a diameter of up to 70 mm - from 5 to 9 m; with a diameter of St. 70 to 219 mm - from 6 to 9 m; with a diameter of St. 219 to 426 mm - from 10 to 12 m. Pipes with a diameter of more than 426 mm are made only in random lengths. By agreement between the manufacturer and the consumer, pipes with a diameter of more than 70 to 219 mm are allowed to be manufactured from 6 to 12 m; multiple length with a multiplicity of at least 250 mm and not exceeding the lower limit established for measuring pipes. The allowance for each cut is set at 5 mm (if no other allowance is specified) and is included in each multiplicity.

Table 1

Outer diameter, mm

Continuation of the table. one

Outer diameter, mm	Theoretical weight of 1 m of pipes, kg, with wall thickness, mm

Continuation of the table. one

Outer diameter, mm	Theoretical weight of 1 m of pipes, kg, with wall thickness, mm

Continuation of the table. one

Outer diameter, mm	Theoretical weight of 1 m of pipes, kg, with wall thickness, mm

Continuation of the table. one

Outer diameter, mm

Theoretical weight of 1 m of pipes, kg, with wall thickness, mm

Continuation of the table. one

Outer diameter, mm	Theoretical weight of 1 m of pipes, kg, with wall thickness, mm

Continuation of the table. one

Outer diameter, mm	Theoretical weight of 1 m of pipes, kg, with wall thickness, mm

Continuation of the table. one

Outer diameter, mm

Theoretical weight of 1 m of pipes, kg, with wall thickness, mm

Notes: 1. In the manufacture of pipes according to GOST 10706, the theoretical mass increases by 1% due to the strengthening of the seam.2. By agreement between the manufacturer and the consumer, pipes are manufactured with dimensions of 41.5 ґ1.5-3.0; 43 ґ1.0; 1.53.0; 43.5 ґ1.5-3.0; 52 ґ2.5; 69.6 × 1.8; 111.8 ґ2.3; 146.1 ґ5.3; 6.5; 7.0; 7.7; 8.5; 9.5; 10.7; 152.4 × 1.9; 2.65; 168 x 2.65; 177.3 ґ1.9; 198 ґ2.8; 203 -2.65; 299 ґ4.0; 530 ґ7.5; 720 ґ7.5; 820 ґ8.5; 1020 ґ9.5; 15.5; 1220 ґ13.5; 14.6; 15.2 mm, as well as with an intermediate wall thickness and diameters within the limits of Table. 1.3. Pipe dimensions enclosed in brackets are not recommended for new design. 3.1. Pipes of measured and multiple lengths are manufactured in two accuracy classes: I - with cutting ends and deburring; II - without chamfering and deburring (with cutting in the line of the mill). 3.2. Limit deviations along the length of measuring pipes are given in Table. 2.

table 2

3.3. Limit deviations along the total length of multiple pipes should not exceed: + 15 mm - for pipes of I accuracy class; + 100 mm - for pipes of accuracy class II. 3.4. At the request of the consumer, pipes of fixed and multiple lengths of accuracy class II must be with chamfered ends and on one or both sides. 4. Limit deviations for the outer diameter of the pipe are given in table. 3.

Table 3

Note. For diameters controlled by perimeter measurement, the largest and smallest perimeter limits are rounded to the nearest 1 mm. 5. At the request of the consumer, pipes according to GOST 10705 are manufactured with a one-sided or offset tolerance on the outer diameter. One-sided or shifted tolerance should not exceed the sum of the maximum deviations given in table. 3. 6. Maximum deviations in wall thickness must correspond to: ± 10% - for pipes with a diameter of up to 152 mm; GOST 19903 - with a pipe diameter of more than 152 mm for a maximum sheet width of normal accuracy. By agreement between the consumer and the manufacturer, it is allowed to manufacture pipes with one-sided tolerance in wall thickness, while the one-sided tolerance should not exceed the sum of the maximum deviations in wall thickness. 7. For pipes with a diameter of more than 76 mm, a wall thickening at the burr by 0.15 mm is allowed. 8. Pipes for pipelines with a diameter of 478 mm or more, manufactured in accordance with GOST 10706, are supplied with maximum deviations in the outer diameter of the ends given in Table. 4.

Table 4

9. The ovality and equivalence of pipes with a diameter of up to 530 mm inclusive, manufactured in accordance with GOST 10705, should not exceed the maximum deviations, respectively, in terms of the outer diameter and wall thickness. Pipes with a diameter of 478 mm or more, manufactured in accordance with GOST 10706, must be of three classes exactly in terms of ovality. The ovality of the end in the pipes should not exceed: 1% of the outer diameter of the pipes for the 1st accuracy class; 1.5% of the outer diameter of the pipes for the 2nd accuracy class; 2% of the outer diameter of the pipes for the 3rd accuracy class. The ovality of the ends of pipes with a wall thickness of less than 0.0 1 of the outer diameter is established by agreement between the manufacturer and the consumer. 10. The curvature of pipes manufactured in accordance with GOST 10705 should not exceed 1.5 mm per 1 m of length. At the request of the consumer, the curves of pipes with a diameter of up to 152 mm should be no more than 1 mm per 1 m of length. The total curvature of pipes manufactured in accordance with GOST 10706 should not exceed 0.2% of the pipe length. The wear curve per 1 m of the length of such pipes is not determined. 11. Technical requirements must comply with GOST 10705 and GOST 10706. Examples of symbols: Pipe with an outer diameter of 76 mm, wall thickness of 3 mm, measured length, accuracy class II and length, made of steel grade St3sp, manufactured according to group B GOST 10705-80:

The same, increased accuracy in outer diameter, length, multiple of 2000 mm, accuracy class 1 in length, made of steel and grade 20, manufactured according to group B GOST 10705-80:

A pipe with an outer diameter of 25 mm, a wall thickness of 2 mm, a length that is a multiple of 2000 mm, an accuracy class II in length, manufactured according to group D GOST 10705-80;

Pipe with an outer diameter of 1020 mm, increased manufacturing accuracy, wall thickness 12 mm, increased accuracy in the outer diameter of the ends, 2nd class accuracy in ovality, random length, made of steel grade and St3sp, manufactured according to group e B GOST 10706 -76 Note. In the symbols of pipes that have undergone heat treatment throughout the volume, the letter T is added after the words "pipe"; pipes that have undergone local heat treatment of the weld - the letter L is added.

INFORMATION DATA

1. DEVELOPED AND INTRODUCED by the Ministry of Metallurgy of the USSR DEVELOPERS V. P. Sokurenko, Ph.D. tech. sciences; V. M. Vorona, Ph.D. tech. Sciences; P. N. Ivshin, Ph.D. tech. Sciences; N. F. Kuzenko, V. F. Ganzina 2. APPROVED AND INTRODUCED BY Decree of the Committee for Standardization and Metrology of the USSR dated 15.11.91 No. 1743 3. INSTEAD OF GOST 10704-76 4. REFERENCE NORMATIVE AND TECHNICAL DOCUMENTS 5. REPUBLICATION. December 1996

In our time, those who wish to purchase high-quality modern binoculars have a lot of opportunities. The choice of the most diverse equipment from world manufacturers is unusually large, including in online stores. But it is best to choose the one that suits you according to technical parameters and at the same time suit the price.

This device is rather complicated technically, and it is sometimes difficult for an ordinary consumer to understand its characteristics. For example, what does "30x60 binoculars" mean? Let's try to find out.

What are binoculars

When starting to choose, decide what approximation is enough for you to observe, will you use the device not only in bright light, but also at dusk, will you be satisfied with a lightweight version with which long-term observation is possible? For the same 30x60 binoculars, reviews can be very different depending on the needs of the owner.

Therefore, it is so important to decide what exactly you are buying this device for and in what conditions you are going to use it.

Binoculars can be theatrical and military, marine or night vision, as well as small compact ones - for those present at the stadium during the competition. Or, on the contrary, large, intended for observations by astronomers. Each variety has its own characteristics. Sometimes they differ quite significantly. To make a good choice, let's get acquainted with the main ones.

What is multiplicity?

This is one of the most important characteristics of such an instrument as binoculars. The multiplicity tells us about the ability to increase the environment. If, for example, its indicator is 8, then, as close as possible, you will consider the observed object at a distance that is 8 times less than the one at which it actually is.

Trying to buy a device with the highest possible multiplicity is unreasonable. This indicator should be related to the circumstances and place of use of the binoculars. For observations in the field, it is customary to use a technique with magnification numbers from 6 to 8. The magnification of binoculars by 8-10 times is the maximum at which you can observe with your hands. If it is higher, jitter, which is also enhanced by optics, will interfere.

Binoculars with significant magnification (from 15-20x) are used in a set with a tripod, on which they are mounted thanks to a special adapter or adapter. Big weight and dimensions are not conducive to long-term wear and in most cases are not needed, especially when the view is obstructed by many obstacles.

Models with variable multiplicity (pancratic) are produced. The degree of magnification in them is changed manually, like photographic lenses. But due to the increased complexity of the device, they are more expensive.

What does "30x60 binoculars" mean, or Let's talk about lens diameter

The marking of any binoculars contains the size of the diameter of the front lens of its objective, which is given directly after the magnification index. For example, what does "30x60 binoculars" mean? These figures are deciphered in this way: 30x is the magnification index, 60 is the size of the lens diameter in mm.

The quality of the resulting image depends on the lens diameter. In addition, it determines the flow of light, binoculars - it is the wider, the larger the diameter. Binoculars marked 6x30, 7x35 or, in extreme cases, 8x42 are considered universal for field conditions. If you are planning to daytime to conduct observations in nature, and rather distant objects are to be considered, take a device with a magnification of 8 or 10 times and a lens with a diameter of 30 to 50 mm. But at dusk they are not very effective due to less light entering the lenses.

The best binoculars for spectators at sporting events are small (pocket type) with parameters around 8x24, they are good for a long shot.

If the light is not enough

In conditions of poor lighting (at dusk or at dawn), one should either prefer a device with a large lens diameter, or sacrifice magnification. The optimal ratio may be 7x50 or 7x42.

A separate group - the so-called night binoculars - active and passive In passive lenses are equipped with a multi-layer coating that eliminates glare. They are used in the presence of minimal lighting (for example, moonlight). Active devices also work in complete darkness, since they use infrared radiation. Their minus is dependence on the power source.

Lovers to study space objects(for example, to consider the relief of the lunar surface) you need binoculars powerful enough, with a magnification of at least 20x. For a more detailed acquaintance with the night sky, it is better for an amateur astronomer to take a telescope, which in this case will not replace even the best binoculars.

What is the viewing angle?

The viewing angle (or its field) is another important characteristic. This value in degrees indicates the span width. This parameter is inversely dependent on magnification - powerful binoculars have a small "angle of view".

Binoculars with a large viewing angle are called wide-angle (or wide-field). It is convenient to take them to the mountains in order to better navigate in space.

Often this indicator is expressed not by a graduated angle, but by the width of a segment or space that can be viewed at a standard range of 1000 m.

Other characteristics of binoculars

The exit pupil diameter is the quotient of the entrance pupil diameter divided by the magnification. That is, for binoculars marked 6x30, this indicator is 5. The optimal number in this case is about 7 mm (the size of a human pupil).

What does "30x60 binoculars" mean in this case? The fact that the size of the exit pupil with this marking is 2. Such binoculars are suitable for not too long observation in good light, then the eyes are threatened with fatigue and overstrain. If the illumination leaves much to be desired, or long-term observation is ahead, this indicator should be at least 5, and preferably 7 or more.

Another parameter - luminosity "manages" the brightness of the image. It is directly related to the diameter of the exit pupil. The abstract number that characterizes it is equal to the square of its diameter. In low light, it is desirable to have this indicator at least 25.

The next concept is focus. Being central, she universal remedy fast focusing. At the same time, its regulator is located near the hinge connecting the pipes. Wearing glasses, it is desirable to have binoculars with a diopter setting.

What else is important

Other, not so global characteristics of binoculars, nevertheless, play a significant role in its choice. Depth of field is the distance to the object of observation, on which it is not required to change the adjusted focus. It is the lower, the greater the multiplicity of the device.

Binoculars are inherent in the property of stereoscopicity (binocularity) characteristic of the human eye, which makes it possible to observe objects in volume and perspective. This is its advantage over a monocular or a telescope. But this quality, useful in the field, interferes in other cases. Therefore, for example, in it is minimized.

According to the systems of optics, binoculars are lens (theatrical, Galilean) and prism (or field). The former have good aperture, direct image, low magnification and narrow field of view. Secondly, prisms are used that turn the inverted image received from the lens into a familiar one. This reduces the length of the binoculars and increases the viewing angle.

The ability of the device to transmit rays of light, expressed as a fraction, is called. For example, with a loss of 40% of light, this coefficient is 0.6. Its maximum value is one.

What is the body of binoculars

Its main advantage is durability. Shockproof qualities are provided by the rubberized housing, thanks to which it also achieves reliability when held in hands and moisture resistance in wet weather.

Modern waterproof binoculars are sealed so that they can be under water at a depth of up to 5 meters for some time without harming themselves. Lenses protect against fogging by filling the space between them with nitrogen. These qualities are important for tourists, hunters, naturalists. Binoculars with a rangefinder will be useful for a researcher, a device with a dim matte surface - for an animal watcher.

Certain non-standard features of individual devices, such as an image stabilizer, or a built-in compass, significantly increase the cost of binoculars and are welcome only when necessary. Decide for yourself whether you really need, for example, binoculars with a rangefinder, whether you are ready to overpay for this option.