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GOST 9941-81 Seamless Cold- and Warm-Deformed Tubes of Corrosion-Resistant Steel. Specifications

GOST 9941-81 · General fastener standards

This is an informational translation of a Russian national standard. The Russian original is authoritative.

I will rework this GOST: I will keep all the technical data and tables, remove references to the original developer, and add metadata following the template.

State Standard of the Union of Soviet Socialist Republics

Seamless cold- and warm-deformed tubes of corrosion-resistant steel

SPECIFICATIONS

GOST 9941-81

SEAMLESS COLD- AND WARM-DEFORMED TUBES OF CORROSION-RESISTANT STEEL Specifications Seamless cold- and warm-deformed tubes of corrosion-resistant steel. SpecificationsGOST 9941-81

Effective date 01.01.83

This standard applies to general-purpose seamless cold- and warm-deformed tubes made of corrosion-resistant steel.

(Revised edition, Amendment No. 2).

1. Size range

1.1. Tubes are manufactured to the outside diameter and wall thickness sizes specified in Table 1.

1.2. Tubes are manufactured in the following lengths:

cut lengths - within the random-length range, but not exceeding the value specified in Table 1, with a length tolerance of +15 mm; by agreement between the manufacturer and the customer, tubes of cut length exceeding the value specified in Table 1 are permitted;

lengths that are a multiple of the cut length - within the cut length, with an allowance of 5 mm for each cut and a tolerance of +15 mm over the entire length. The minimum multiple length is 300 mm;

random lengths - for wall thickness up to 0.5 mm, from 0.75 m to the value specified in Table 1;

for wall thickness from 0.5 to 1 mm, from 1.0 m to the value specified in Table 1;

for wall thickness of 1.0 mm and over, from 1.5 to 12.5 m;

by agreement between the manufacturer and the customer, tubes longer than 12.5 m are permitted.

By agreement between the manufacturer and the customer, tubes with a diameter up to 25 mm are manufactured with a length up to 16 m.

(Revised edition, Amendment No. 2).

1.3. In a lot of random-length tubes, no more than 6% of tubes of the following lengths are permitted:

from 0.5 to 0.75 m - for wall thickness up to 0.5 mm;

from 0.75 to 1 m - for wall thickness from 0.5 to 1 mm;

from 0.75 to 1.5 m - for wall thickness of 1 mm and over.

(Amended edition, Amendment No. 1).

Table 1

Outside diameter, mmTube length, m, max, at wall thickness, mm
0.20.30.40.50.60.81.01.21.41.51.82.02.22.52.83.03.23.54.04.55.05.56.06.57.07.58.08.59.09.51011121416182022
55667777-------------------------------
65667777777----------------------------
75667777777----------------------------
8566777777777--------------------------
9566777777777-------------------------
1056677777777777------------------------
1156677777777777------------------------
1256677777777777------------------------
1356677777777777------------------------
145667777777777777----------------------
155667777777777777----------------------
165667777777777777----------------------
175667777777777777----------------------
18566777777777777777--------------------
19566777777777777777--------------------
205667777777777777777-------------------
21-667777777777777777-------------------
22-667777777777777777-------------------
23-667777777777777777-------------------
24-667777777777777777-------------------
25-6677777777777777777------------------
27-6677777777777777777------------------
28-6677777777777777777------------------
30-667777777777777777777----------------
32-666677777777777777777----------------
34-666677777777777777777----------------
35-666677777777777777777----------------
36--66677777777777777777----------------
38--666777777777777777777---------------
40--666777777777777777777---------------
42--666777777777777777777---------------
45--666777777777777777777---------------
48--666777777777777777777777------------
50--666777777777777777777777------------
51---66777777777777777777777------------
53---66677777777777777777777------------
54---66677777777777777777777------------
56---66677777777777777777777------------
57---666777777777777777777777-----------
60---6667777777777777777777777----------
63---------7777777777777777777----------
65---------7777777777777777777----------
68---------7777777777777777777----------
70---------7777777777777777777----------
73---------7777777777777777777----------
75---------7777777777777777777----------
76---------------7777777777777----------
80---------------7777777777777----------
83---------------7777777777777----------
85---------------7777777777777----------
89---------------7777777777777----------
90---------------7777777777777----------
95---------------7777777777777777-------
100---------7777777777777777777777-------
102---------7777777777777777777777-------
108---------7777777777777777777777-------
110---------777777777777777777777777-----
120---------777777777777777777777777-----
130-----------77777777777777777777777777-
140-----------77777777777777777777777777-
150-----------77777777777777777777777777-
160-------------7777777777777777777777777
170-------------7777777777777777777777777
180-------------7777777777777777777777777
200-------------77777777777777777777777--
220---------------7777777777777777777----
250---------------7777777777777777777----
273----------------------6.56.5665.55.555544-----

Notes:

  1. Requirements for thin-wall tubes with a D/s ratio ≥40, in terms of technical characteristics and dimensional tolerances, are established by regulatory and technical documentation

  2. Tubes of steel grades 12×17, 08×17T, 15×25T are manufactured with an outside diameter of not less than 21 mm; tubes of alloy 06KhN28MDT are manufactured with an outside diameter of 14-85 mm and a wall thickness of 1-5 mm.

  3. The mass of one metre of length is calculated in kilograms using the formula

where D is the nominal outside diameter, mm;

s is the nominal wall thickness, mm;

  • density of the metal, g/cm³, depending on the steel grade, in accordance with Table 3

1.4. Tolerances on the outside diameter and wall thickness of tubes shall not exceed those specified in Table 2.

Table 2

Tube dimensions, mmTolerances for manufacturing accuracy
ordinaryincreasedhigh
Along the outer diameter
for diameter: from 5 to 10±0.3 mm±0.2 mm±0.15 mm
over 10 to 30±0.4 mm±0.3 mm±0.2 mm
over 30 to 95±1.2%±1.0%±0.8%
over 95±1.0%±1.0%±0.8%
For wall thickness
for wall thickness: 0.2±0.05 mm±0.03 mm-
from 0.3 to 0.4±0.07 mm±0.05 mm-
from 0.5 to 0.6±0.10 mm±0.07 mm-
from 0.7 to 1±0.15 mm±0.10 mm-
over 1 to 3+12.5 15.0%±12.5%+12.5 -10.0%
over 3 to 7±12.5 %+12.5 -10.0%±10%
over 7-10.0%±10%-

Continuation of Table 2

Tube dimensions, mmTolerances for manufacturing accuracy
ordinaryhigh
For tubes of sizes delimited by the broken line in Table 1
Along the outer diameter±1.2%±1%
For wall thickness
for wall thickness: from 1.5 to 2.5±15%+12.5 -15.0%
over 2.5 to 4+12.5 -15.0%±12.5%
For tubes of alloy grade 06KhN28MDT
Along the outer diameter±0.45 mm-
for diameter: up to 30±1.2%-
over 30
For wall thickness±15.0%-
for wall thickness: up to 3±12.5%-
over 3

At the customer’s request, tubes are manufactured with combined tolerances on diameter and wall thickness.

1.5. At the customer’s request, tubes are manufactured to the inside diameter and wall thickness. Tolerances on the inside diameter are established by agreement between the manufacturer and the customer.

1.6. The ovality of tubes shall not cause the tube diameter to exceed the tolerances on the outside diameter.

1.7. The curvature of tubes over any 1 m length shall not exceed:

1 mm - for tubes with a diameter of 5 mm and over, with a wall thickness of 0.5 mm and over;

2 mm - for tubes with a diameter over 15 mm, with a wall thickness of less than 0.5 mm.

For tubes with a diameter of less than 15 mm, with a wall thickness of less than 0.5 mm, curvature limits are not regulated; such tubes shall not have sharp kinks.

1.8. The ends of tubes shall be cut at a right angle and cleaned of burrs; a chamfer and roughness resulting from their removal are permitted. At the customer’s request, the ends of tubes with a wall thickness over 5 mm shall have a chamfer for welding.

Examples of designations

Tube with an outside diameter of 25 mm, wall thickness 2 mm, ordinary manufacturing accuracy, random length, made of steel grade 12×18N10T:

Tube 25´2-12×18N10T GOST 9941-81

Same, high manufacturing precision (v), length multiple of (kr) 1000 mm:

Pipe 25v´2v´1000kr - 12×18N10T GOST 9941-81

Same, normal manufacturing precision, fixed length (m) 3000 mm:

Pipe 25´2´3000m - 12×18N10T GOST 9941-81

Same, but with increased manufacturing precision (p), cut-to-length (m) 3000 mm:

Pipe 25p´2p´3000m - 12Kh18N10T GOST 9941-81

Same, but with high manufacturing precision (v), cut-to-length (m) 3000 mm, manufactured to inner diameter (vn) and wall thickness:

Pipe vn 25v´2v´3000m - 12Kh18N10T GOST 9941-81

(Amended edition, Amendments No. 2, 5, Corrigendum.)

2. Technical requirements

2.1. Pipes shall be manufactured in accordance with the requirements of this standard and process regulations approved in the prescribed manner.

(Amended edition, Amendment No. 2.)

2.2. Pipes shall be manufactured from steel grades specified in Table 3, with chemical composition per GOST 5632.

Pipes may be manufactured with micro-additions of rare earth metals.

The sulfur content in steel for pipes subject to welding, as specified in the order, shall not exceed 0.02%.

(Amended edition, Amendments No. 3, 5.)

2.3. Pipes shall be heat-treated. At the customer’s request, pipes may be manufactured without heat treatment and surface brightening. Standards for mechanical properties and curvature of pipes without heat treatment are established by agreement between the manufacturer and the customer.

2.4. The mechanical properties of pipes shall comply with those specified in Table 3.

The yield strength for pipes made of 12Kh18N10T steel shall be not less than 216 MPa (22 kgf/mm²). Yield strength values for pipes made of 12Kh18N12T, 10Kh17N13M2T and 08Kh18N10T steel are established by agreement between the manufacturer and the customer.

Table 3

Steel gradeTensile strength σB, N/mm² (kgf/mm²)Elongation δ₅, %Density ρ, g/cm³
min
08×17T372(38)177.70
08×13372(38)227.70
12×13392(40)227.70
12×17441(45)177.70
15×25T461(47)177.60
04×18N10490(50)457.90
08×20N14S2510(52)357.70
10Kh17N13M2T529(54)358.00
08×18N12B529(54)377.90
10×23N18529(54)357.95
08×18N10529(54)377.90
08Kh18N10T549(56)377.90
08×18N12T549(56)377.95
08×17N15M3T549(56)358.10
12Kh18N10T549(56)357.95
12×18N12T549(56)357.90
12×18N9549(56)377.90
17×18N9568(58)357.90
08×22N6T588(60)207.60
08KhN28MDT490(50)307.96

Determination of yield strength for pipes made of 12Kh18N10T, 10Kh18N12T, 10Kh17N13M2T and 08Kh18N10T steel is performed at the customer’s request.

(Amended edition, Amendments No. 3, 4, 5.)

2.5. At the customer’s request, pipes shall withstand a tensile test at a temperature of 350°C.

Standards for tensile strength and yield strength are established by agreement between the manufacturer and the customer.

(Amended, Amendment No. 4).

2.6. The outer and inner surfaces of pipes shall be free of slivers, tears, laps and cracks. Defects may be removed by local dressing, full or local grinding, boring and turning, provided that the extent of boring, turning or full grinding does not take the diameter and wall thickness beyond the minus tolerances, and that local dressing and grinding does not take the wall thickness beyond the minus tolerances specified in Table 2.

Individual slivers, score marks, pitting, scratches and dents are permitted without dressing, provided that they do not take the wall thickness beyond the minus tolerances.

At the customer’s request, individual slivers shall be dressed off.

(Amended edition, Amendment No. 3).

2.7. The surface of pipes shall be bright. A matte surface with a grey tint resulting from the production method and steel grade is permitted.

Pipes may be manufactured without subsequent pickling after heat treatment in a protective atmosphere or vacuum, with temper colours on the surface.

2.8. At the customer’s request, pipes made of 12Kh18N10T, 12Kh18N12T, 12Kh18N9, 17Kh18N9, 04Kh18N10, 08Kh20N14S2, 10Kh17N13M2T, 08Kh18N12B, 10Kh23N18, 08Kh18N10T, 08Kh18N10, 08Kh18N12T, 08Kh17N15M3T, 06KhN28MDT steel shall withstand flattening until the distance (H) in millimetres between the flattening surfaces, calculated using the formula, is reached

where s is the nominal wall thickness, mm;

D is the nominal outer diameter, mm,

or expanding until the outer diameter increases by 10% using a mandrel with a cone angle of 30°; mandrels with a cone angle of 6 and 12° may also be used.

2.9. At the customer’s request, pipes shall withstand hydraulic pressure in accordance with the requirements of GOST 3845 at an allowable stress equal to 40% of the tensile strength for the given steel grade. The ability of pipes to withstand hydraulic pressure is ensured by the production process.

2.10. At the customer’s request, as specified in the order, pipes made of 10Kh17N13M2T, 08Kh17N15M3T, 08Kh22N6T, 04Kh18N10, 08Kh18N10, 08Kh18N10T, 12Kh18N10T, 08Kh18N12T, 12Kh18N12T, 12Kh18N9, 08Kh18N12B steel and 06KhN28MDT alloy shall be resistant to intergranular corrosion.

(Amended, Amendment No. 5).

2.11. At the customer’s request, pipes shall undergo ultrasonic testing. The dimensions of the artificial defect are established by agreement between the manufacturer and the customer.

3. ACCEPTANCE RULES

3.1. Pipes shall be accepted in lots.

A lot shall consist of pipes of the same size in diameter and wall thickness, the same steel grade and the same type of heat treatment, and, at the customer’s request, the same melt, and shall be accompanied by a single quality document in accordance with GOST 10692, supplemented with: chemical composition in accordance with the quality document for the pipe billet, as well as information on heat treatment.

The number of pipes in a lot shall not exceed 300 pcs.

3.2. Each pipe shall be subjected to surface inspection, dimensional inspection, hydraulic pressure testing, and ultrasonic testing.

3.3. For quality control purposes, the following shall be sampled from the lot:

for tensile testing - two pipes;

for flattening or expanding testing - one pipe;

for intergranular corrosion testing - two pipes.

If unsatisfactory test results are obtained for at least one of the parameters, repeat tests shall be carried out on that parameter using double the number of pipes sampled from the same lot.

The results of repeat tests apply to the entire lot.

(Amended, Amendment No. 5).

3.4. (Deleted, Amendment No. 5.)

4. TEST METHODS

4.1. For quality control, one specimen shall be cut from each sampled pipe for each type of test.

4.2. Inspection of the pipe surface shall be performed visually.

4.3. The length of pipes shall be checked with a measuring tape per GOST 7502.

(Amended, Amendment No. 5).

4.4. The curvature of pipes shall be checked with a straightedge per GOST 8026 and a feeler gauge per regulatory documentation.

(Amended edition, Amendments No. 4, 5.)

4.5. The diameter and ovality of pipes shall be checked with a plain micrometer type MK per GOST 6507, and with sheet snap gauges per GOST 18360, GOST 18365.

Wall thickness shall be checked with a pipe micrometer type MT per GOST 6507.

(Amended, Amendment No. 5).

4.6. Tensile testing shall be performed per GOST 10006, GOST 19040 (at a temperature of 350°C). The travel speed of the moving grip shall not exceed 10 mm per minute. The test speed may be increased to up to 40 mm per minute after the yield strength has been reached.

Mechanical properties may be checked by the hardness method in accordance with regulatory and technical documentation.

In case of disagreement in the assessment of results, the test shall be carried out per GOST 10006 and GOST 19040.

4.7. Expanding tests shall be carried out on pipes with a diameter of up to and including 150 mm and a wall thickness of not more than 10 mm, per GOST 8694.

4.8. Pipes manufactured without heat treatment shall not be subjected to flattening and expanding tests or to checks for susceptibility to intergranular corrosion.

4.9. Flattening tests shall be carried out on pipes with a wall thickness of not more than 10 mm, per GOST 8695.

At the customer’s request, flattening tests shall be carried out on pipes with a wall thickness of not more than 15% of the outer diameter.

If minor defects resulting from external defects permitted without dressing are detected on flattened specimens, a repeat test may be carried out on a specimen sampled from the same pipe, with the surface pre-dressed to a depth of half the tolerance, but not more than 0.2 mm, on the side where the defects were found

(Amended edition, Amendment No. 1).

4.10. Hydraulic pressure testing shall be carried out per GOST 3845, with pipes held under pressure for not less than 10 s.

4.10.1. Instead of hydraulic pressure testing, each pipe may be inspected by non-destructive methods per GOST 17410 and regulatory and technical documentation, effective from 01.01.90.

(Added, Amendment No. 2).

4.11. Ultrasonic testing shall be carried out per GOST 17410 and regulatory and technical documentation.

4.12. Resistance to intergranular corrosion shall be checked for all steel grades except 06KhN28MDT using methods AM or AMU, and for the 06KhN28MDT alloy using method VU, per GOST 6032-89. In case of disagreement in the assessment of results, all steel grades except 06KhN28MDT shall be checked using method AM.

By agreement between the manufacturer and the customer, the resistance of 12Kh18N10T and 08Kh18N10T steels to intergranular corrosion may be checked using method PT per GOST 9.914-91. In case of disagreement in the assessment of results, the check shall be carried out using method AM per GOST 6032-89.

(Amended edition, Amendment No. 2, 5).

5. MARKING, PACKAGING, TRANSPORTATION AND STORAGE

5.1. Marking, packaging, transportation and storage shall be carried out per GOST 10692.

INFORMATIONAL DATA

  1. SUPERSEDES GOST 9941-72

  2. REFERENCE REGULATORY AND TECHNICAL DOCUMENTS

Designation of the referenced regulatory documentClause numberDesignation of the referenced regulatory documentClause number
GOST 3845-752.9 , 4.10GOST 9941-811.8
GOST 5632-722.2GOST 10006-804.6
GOST 6032-894.12GOST 10692-803.1 , 5.1
GOST 6507-904.5GOST 17410-784.10.1 , 4.11
GOST 7502-984.3GOST 18360-934.5
GOST 8026-924.4GOST 18365-934.5
GOST 8694-754.7GOST 19040-814.6
GOST 8695-754.9
  1. The validity period restriction was lifted under the Protocol of the Interstate Council for Standardization, Metrology and Certification (IUS 2-93)
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