GOST 8731-74

• gost-8731-74.pdf (279.66 KiB)
  ГОСТ 8731-74

The Tubes GOST 8731−74 seamless hot-deformed steel. Technical requirements (Amendments N 2−6)

GOST 8731−74

Group В62

INTERSTATE STANDARD

PIPES STEEL SEAMLESS HOT-DEFORMED

Technical requirements

Seamless hot-deformed steel pipes.
Specifications

ISS 23.040.10
OKP 13 1200, 13 1700, 1900 13

Date of introduction 1976−01−01

INFORMATION DATA

1. DEVELOPED AND INTRODUCED by the Ministry of ferrous metallurgy of the USSR

DEVELOPERS

E. A. Bliznyuki, V. P. Sokurenko, V. N. Rivne

2. APPROVED AND put INTO EFFECT by Decision of the USSR State Committee for standards from 19.11.74 N 2560

3. REPLACE GOST 8731−66

4. REFERENCE NORMATIVE AND TECHNICAL DOCUMENTS

6. Limitation of actions taken by Protocol No. 6−94 of the Interstate Council for standardization, Metrology and certification (ICS 3−96)

7. EDITION Changes N 2, 3, 4, 5, 6, approved in February 1976, March 1980, January 1982, March 1984, April 1992 (IUS 4−76, 4−80, 4−82, 6−84, 7−92)


This standard applies to hot seamless pipes of General purpose carbon steel and alloy steel.

(Changed edition, Rev. N 6).

1. TECHNICAL REQUIREMENTS

1.1. The pipe dimensions and limit deviations shall be as specified in GOST 8732, GOST 9567.

1.2. Depending on the quality parameters of the pipe shall be manufactured of the following groups:

And — with standard mechanical properties specified in table.1, of steel grades St2sp, St4sp, St5sp, St6sp according to GOST 380;

Table 1

Note. By agreement between manufacturer and consumer is made of tubes of steel grade st3sp.


B — with standard chemical composition of steel grades according to GOST 380, GOST 1050, GOST 4543, GOST 19281;

In — with standard mechanical properties specified in table.2, and the chemical composition of steel grades according to GOST 1050, GOST 4543, GOST 19281, GOST 380;

Table 2

Notes:

1. In the manufacture of pipes with wall thickness more than 45 mm the mechanical properties shall be established in consultation with the consumer.

2. Mechanical properties of pipes made from steel grades not listed in table.2, and the rules of impact strength and relative contraction for steel of all grades are established by agreement between manufacturer and consumer.


G — standard chemical composition of steel grades according to GOST 1050, GOST 4543 host 19281, with control of mechanical properties of thermally treated samples. Norms of mechanical properties should correspond to those in standards for steel;

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

(Changed edition, Rev. N 4, 5, 6).

1.3. At the request of the consumer pipe shall be manufactured heat treated. Heat treatment regime and norms of mechanical properties are set according to normative-technical documentation approved in the established order.

1.4. On the surface of the pipe are not allowed cracks, slivers, flaws and sunsets.

Allowed some minor nicks, dents, risks, thin layer of oxides, traces of Stripping defects and small slivers, if they do not take wall thickness outside negative deviations.

Note. For pipes intended for the manufacture of parts by machining, additional requirements are established by agreement between manufacturer and consumer.

1.3, 1.4. (Changed edition, Rev. N 4).

1.5. The pipe ends must be cut at right angle, at the same time allowed the formation of the chamfer at an angle of at least 70° to the axis of the pipe. The pipe ends must be cleaned of burrs; allowed the formation of a chamfer at their removal.

1.6. It is allowed to trim the ends of tubes with wall thickness of 20 mm or more oxy-fuel, plasma cutting or saw.

When cutting pipes with a torch or plasma cutting the stock to length of the pipes should be at least 20 mm for each cut.

1.7. On demand of the consumer is allowed to produce pipe with a wall thickness of 20 mm or more, manufactured from rolled or forged blanks, without cropping the ends. In this uncut part of the pipe marked with paint and the length of the pipe at delivery not included.

1.8. At the request of the consumer at the ends of the pipes to be welded, with wall thickness from 5 to 20 mm should be removed chamfer with the angle of 35° to 40° to the pipe end. This should be left to the socket ring width of 1−3 mm.

1.9. Pipe of all types, pressure (the working conditions of the pipes are specified in the order), shall withstand the hydraulic test pressure is calculated according to the formula specified in GOST 3845 where  — allowable stress equal to 40% of the temporary tear resistance for this grade of steel.

The ability of pipe to withstand hydraulic pressure is provided by the technology of production of pipes.

1.7−1.9. (Changed edition, Rev. N 4).

1.9. At customer’s request, tubes shall withstand hydraulic pressure in accordance with the requirements of GOST 3845, but not more than 20 MPa (200 kgf/cm).

In coordination with the consumer of the pipe experience a hydraulic pressure of over 20 MPa (200 kgf/cm).

Instead of hydraulic tests is allowed to carry out inspection of each pipe using non-destructive methods to ensure that pipes standards hydraulic test pressure.

(Added, Rev. N 4).

1.10. At customer’s request, tubes of steel grades 10, St2sp, 20, St4sp and 15KHM depending on the purpose and conditions of work must be able to withstand one or several technological tests specified in paras.1.11−1.14.

(Changed edition, Rev. N 4).

1.11. Pipe shall withstand a bend test.

1.12. Test distribution must be able to withstand the pipe diameter 159 mm, wall thickness not over 8 mm on the mandrel with a taper of 1:10 to increase the outer diameter specified in the table.3.

Table 3

1.13. The test is subjected to a flattening of the pipe with a wall thickness not exceeding 10 mm to obtain sludinajumi between surfaces distance () in mm, calculated by the formula

,

where =0,09 for steel of grade 10;

=0.08 for other steel grades;

 — nominal wall thickness, mm;

 — nominal outside diameter of pipe, mm.

(Changed edition, Rev. N 2).

1.14. Test turn-up cuffs to withstand pipe outer diameter not less than 30 mm and not more than 160 mm with a wall thickness:

no more than 10% of external diameter for tubes with external diameter up to 60 mm;

no more than 8% of the outer diameter for pipes with outside diameters over 60 to 108 mm;

no more than 6% of the outer diameter — pipe outside diameter in excess of 108 to 140 mm;

no more than 5% of the outer diameter for pipes with outside diameter of more than 140 to 160 mm.

Width bent sides, measured from the inner surface of the pipe, shall be not less than 12% of the inner diameter of the pipe and not less than 1.5 times the wall thickness.

The angle of the flanging shall be:

90° — for pipes of steel grades 10, St2sp;

60° — for pipes of steel grades 20, St4sp, 15HM.

1.15. At the customer’s request pipes with a wall thickness of 12 mm and more check out the macrostructure.

It should not be traces of shrinkage, voids, cracks, bubbles and other defects that are visible without special instruments.

Note. Tubes produced directly from an ingot, control of macrostructure are not exposed.


(Changed edition, Rev. N 4).

2. ACCEPTANCE RULES

2.1. Pipes take by the parties. The party should consist of pipes of the same size in diameter and wall thickness, same steel, same heat treatment (heat-treated tubes) and be accompanied by one document on quality to suit shost 10692, with the addition of: chemical composition of steel in accordance with the document on the quality of the workpiece.

(Changed edition, Rev. N 4).

2.2. The number of tubes in the party should be.:

400 — for pipes with a diameter less than 76 mm;

200 for pipes of other sizes.

Allowed to increase lot size up to 600 pieces for pipes with a diameter less than 76 mm and wall thickness not exceeding 2.5 mm.

2.3. At customer’s request, the party shall consist of pipes, one made of steel melting.

(Changed edition, Rev. N 4).

2.4. Each tube shall be subjected to inspection and measurement.

2.5. The chemical composition of the steel pipe is taken on the document on the manufacturing quality of the workpiece. If there is disagreement carried out chemical analyses.

2.6. To control the macrostructure, mechanical properties, on the bend, on the hand, flattening and turn-up cuffs pick up two tubes from the party. To test the hardness of selected 2% of the pipes (but not less than two pipes) from the party.

Test hydraulic pressure in accordance with claim 1.9 and is subjected to each pipe.

To check the chemical composition of the selected one pipe from the party.

(Changed edition, Rev. N 4).

2.7. (Deleted, Rev. N 4).

2.8. The yield strength and Brinell hardness number of steel pipes is determined by the requirement of the user.

(Changed edition, Rev. N 4).

2.9. (Deleted, Rev. N 4).

2.10. If unsatisfactory test results of at least one of the indicators it is carried out re-testing at twice the sample from the same batch.

The results of repeated tests are final and apply to the entire party.

3. TEST METHODS

3.1. For each test (except test of macrostructure and hardness) from each selected pipe cut out one sample.

To control the macrostructure of the samples taken from both ends of the pipe.

To determine the number of samples allowed application of statistical control methods.

(Changed edition, Rev. N 4).

3.2. Inspection of pipes produced without the use of magnifying devices. The depth of the defects check adproval or otherwise.

Allowed to control the geometric dimensions and surface quality of the pipes with special devices.

3.3. If there are differences in the quality of the steel chemical composition determines the churchyard 22536.0 to GOST 22536.1−22536.6 GOST, GOST 12344−12365 GOST, GOST 28473.

(Changed edition, Rev. N 6).

3.4. To determine the chemical composition of the steel samples are taken according to GOST 7565.

3.5. The tensile test is carried out according to GOST 10006 on the longitudinal proportionate short sample. For samples in the form of a strip or tube segment speed tests to the yield strength should be not more than 10 mm/min, yield point is not more than 40 mm/min.

Allowed to control the mechanical properties of pipes non-destructive methods according to normative-technical documentation.

In case of disagreement in the evaluation of test results carried out according to GOST 10006.

(Changed edition, Rev. N 3, 6).

3.6. The hardness test is carried out according to GOST 9012 on both ends of the pipe.

Allowed to determine the hardness of the specimens intended for the tensile test.

Allowed to control hardness non-destructive methods.

In case of dispute, the test performed according to GOST 9012.

(Changed edition, Rev. N 4).

3.7. Test pipes for flattening is carried out according to GOST 8695.

3.8. When discovering a tapered samples tiny tears or other minor defects allowed to re-test flattening of another sample taken from the same tube with the preliminary removal of the surface layer of the sample (inner and outer) to a depth of not more than 0.2 mm for pipe diameters up to 108 mm and not more than 1 mm for pipes with a diameter of 114 mm or more.

3.9. Hydraulic testing of the pipes is carried out according to GOST 3845 with time under pressure of not less than 10 s.

3.10. Test pipe at the bend is carried out according to GOST 3728.

3.11. Test pipes for the distribution is carried out according to GOST 8694.

3.12 Test pipes on a turn-up cuffs is carried out according to GOST 8693.

3.13. Macrostructure of the metal pipes checked for ProTrainer cross ring sample.

4. MARKING, PACKAGING, TRANSPORTATION AND STORAGE

4.1. Marking, packaging, transportation and storage are produced according to GOST 10692.