One of the methods for producing stainless steel pipes is the seamless method. The final product is obtained from pipe billet as a result of chemical and thermal treatment, sequence mechanical deformations. According to the content of the production process, seamless pipe is manufactured using cold or hot rolling technology.

Cold- and heat-deformed seamless stainless steel pipes

The cold process has significant advantages:

1. Minimal metal loss.
2. Possibility of obtaining a wide range of pipe sizes from similar blanks.
3. Allows the production of products with a wall thickness of 0.2 mm.
4. Minimize wall thickness deviations.
5. Excellent surface quality of finished products.
6. Durability.

Requirements for pipes according to GOST 9941-81

The surface of the products should not have cracks, caps, or sunsets. External damage resulting from deadening deformation must be cleaned (grinded) without going beyond standard limits. These indicators are reflected in tables 1 and 2.

For product sizes (diameter x wall thickness, mm):

• 100-102 x 1.5-2.9;
• 108-120 x 1.5-3.2;
• 130-150 x 2-3.2;
• 160-200 x 2.5-3.5;
• 220 x 3-3.5;
• 250 x 3-4 -

maximum deviations are specifically specified and shown in Table 3.

The standard sets requirements for the curvature parameter of products produced by the seamless cold-rolling method. This value is indicated per 1 m of pipe and is for the diameter:

• less than 15 mm: 1 mm.
• over 15 mm: 2 mm.

For products with a diameter of up to 15 mm and a wall of up to 0.5 mm, the maximum curvature is not normatively established: it can be any, without kinks.

The surface of the pipes is light. Features of the manufacturing process and metal grade may result in dull color.

Tubular products produced by the cold-deformed method must withstand a number of tests:

• for tension at a temperature of 350 degrees C;
• flattening/distributing to calculated parameters;
• hydraulic pressure at a stress of 40% tensile strength of steel type;
• for intergranular corrosion;
• ultrasonic testing.

Cold rolling technology for steel pipes

Direct deformation of the workpieces is preceded by chemical preparation - etching. Steel with chromium alloying content is etched with alkaline melts and acid solutions. The result is the transformation and removal of iron oxides and scale.

Next, the pipes are washed with hot and cold water, dried at a temperature of 170 degrees C, special coatings are applied to prevent the occurrence of defects during further deformations. When rolled through a mill, the workpieces do not come into direct contact with the milling tools.

Billets pass through rolling mills several times. At intermediate stages they are subject to additional chemical influences. A significant role is played by heat treatment up to 700-800 degrees C, as a result of which the hardness of the metal decreases (annealing). After deformation, thermal hardening is carried out, as a result of which the mechanical properties of the products increase.

Dimensions of seamless pipes according to GOST 9941-81 - table

Hot rolled seamless steel pipes

Hot technical process gives finished goods the following advantages:

1. Ideal anti-corrosion properties.
2. Durability and resistance to impacts.
3. Allows the production of products with walls up to 32 mm.
4. Competitive price.

Standards for pipes according to GOST 9940-81

Hot-deformed pipes are cleaned of scale and have no external defects on both surfaces. If products are subject to further welding, then the mass fraction of sulfur in the material is normatively limited to 0.02%.

The curvature of finished hot-deformed products is established normatively. This value is indicated relative to the wall thickness per 1 m of pipe and is:

• with a wall less than or equal to 10 mm: 1.5 mm;
• with a wall of 10-20 mm: 2 mm;
• with a wall more than 20 mm: 4 mm.

The standard's requirements for passing the hydraulic test, tensile test and others are similar to the tests established for products produced by the cold-deformed method.

Hot rolling steel technology

Unlike the cold rolling method, which involves heat treatment of blanks and products at some stages, the hot rolling method is completely carried out on heated metal. For this purpose, special furnaces with a so-called walking hearth are used, in which an excess pressure of up to 29.4 Pa is formed.

• crimping machine;
• piercing mill, in which the workpiece becomes a pipe with walls;
• rolling on a continuous mill;
• induction heating and reduction mill.

After reduction, the finished pipes are cooled and cut into the required lengths.

Dimensions of seamless pipes GOST 9940-81 - table

GOST has introduced additional restrictions on the diameter of products for some steel grades:

• 108 mm - 08Х20Н14С2, 08Х22Н6Т, 08Х18Н12Б.
• 140 mm - 08Х17Н15М3Т.
• 168 mm - 10Х23Н18.
• 219 mm - 10Х17Н13М2Т, 15Х28, 08Х17Т, 12Х17.

Main grades of stainless steel for seamless pipes

GOSTs 9940 and 9941 contain 20 grades of alloys that can be used for the manufacture of stainless steel seamless pipes. Of these, the most used are presented below.

Steel 12x18n10t

The steel has excellent anti-corrosion properties, is resistant to oxidation at temperatures up to 900 degrees C, and has high heat resistance.

Properties of pipes made from steel 12x18n10t by cold/hot rolling:

• resistance, kgf/sq.mm: 56 / 54;
• elongation,%: 35 / 40;
• density, g/cc: 7.95 / 7.9.

Tubular products made from this steel are used for transporting oxidizing media, organic solvents and some types of organic acids in cryogenic technologies at temperatures close to absolute zero.

Steel grade 08x18n10t

Stainless steel of this brand is characterized by even better properties for transporting aggressive media than the previous type. Finds its application in chemical industry as exhibiting high parameters of resistance to intergranular corrosion.

Mechanical properties of pipe products made from steel 08x18n10t by cold/hot rolling:

• resistance, kgf/sq.mm: 54 / 52;
• elongation,%: 37 / 40;
• density, g/cc: 7.9.

Pipes made of this type of steel can be operated at any pressure and temperature up to 600 degrees C.

Steel 10x17N13M2T

The type of steel contains 3% molybdenum, which gives it additional properties that steel 12x18 and 08x18 lack. Pipes made from 10x17N13M2T are resistant to chlorine. In acidic environments, depending on the type of acid, its concentration and temperature, the annual corrosion rate does not exceed 0.1 mm.

• The mechanical properties of products made from 10x17N13M2T by cold and hot rolling are the same and are:
• resistance, kgf/sq.mm: 54;
• elongation, %: 35;

density, g/cc: 8

Steel grade 06xN28MDT Stainless steel contains molybdenum (up to 3%), increased amounts of nickel (up to 29%) and chromium (up to 25%). Used in industrial installations

• requiring transportation of acids and other aggressive media.
• In accordance with the standard, this grade of steel is used in the production of pipes using the cold rolling method. The mechanical properties of the products are as follows:
• resistance, kgf/sq.mm: 50;

elongation, %: 30;

density, g/cc: 7.96

For cold-rolled pipes made of 06xN28MDT, special permissible deviations in diameter and wall are established (Table 8). Steel 10x23N18 Belongs to the group of heat-resistant alloys. Can be used to work with aggressive media with temperatures up to 1000 degrees C. For more

Properties of pipes made from 08x18n10t by cold/hot rolling:

• resistance, kgf/sq.mm: 54 / 50;
• elongation,%: 35 / 37;
• density, g/cc: 7.95.

Media transported under high pressure at temperatures up to 1000 degrees C lead to a reduction in the service life of products to 1-10 thousand hours.

Scope of application of seamless steel pipes

Seamless technology is one of the main methods for producing thin-walled and thick-walled stainless steel pipes with a precise internal channel. They apply:

• in high pressure installations;
• in power plants;
• in mechanical engineering and aviation industry;
• in the chemical and food industries;
• in gas and oil pipelines.

The scope of their application is wide and covers highly specialized types of production and industry.

Electric welded stainless steel pipes

The second method of producing stainless steel tubular products is the simpler and more economical electric welding method.

Welded pipe manufacturing methods

Main difference welding method from seamless in that it involves the production of a pipe not from a finished billet through numerous deformations, heat and chemical treatments, but by welding a steel sheet bent into a pipe. Next, water cooling, calibration, cutting, and control measures are carried out. If necessary, perform postural deformation.

Significant reduction in the cost of production of stainless steel products welded method made it possible to use them in everyday life: for pipelines, for decorative and construction purposes.

Yulia Petrichenko, expert

Regulatory documents for welded stainless steel pipes

Technical specifications for electric-welded products made of anti-corrosion steel are set out in GOST 11068-81. The specification of profile pipes of square and rectangular shape is contained in GOST 8639-82 and GOST 8645-68, respectively.

Dimensions of electric welded stainless steel pipes

Table 9. Dimensions of products made of stainless steel by welding.

Outer diameter, mm	Wall thickness, mm
	0,8	1,0	1,2	1,4	1,5	1,8	2,0	2,2	2,5	(2,8)	3,0	(3,2)	3,5	4,0
8	X	X	X	-	-	-	-	-	-	-	-	-	-	-
9	X	X	X	-	-	-	-	-	-	-	-	-	-	-
10	X	X	X	-	-	-	-	-	-	-	-	-	-	-
11	-	X	X	X	X	X	-	-	-	-	-	-	-	-
12	X	X	X	X	X	X	X	-	-	-	-	-	-	-
14	X	X	X	X	X	X	-	-	-	-	-	-	-	-
15	-	X	X	X	X	X	-	-	-	-	-	-	-	-
16	X	X	X	X	X	X	X	X	-	-	-	-	-	-
(17)	-	X	X	X	X	X	X	X	-	-	-	-	-	-
18	-	X	X	X	X	X	X	X	-	-	-	-	-	-
(19)	-	X	X	X	X	X	X	X	-	-	-	-	-	-
20	-	X	X	X	X	X	X	X	-	-	-	-	-	-
22	-	X	X	X	X	X	X	X	-	-	-	-	-	-
25	-	X	X	X	X	X	X	X	X	-	-	-	-	-
28	-	-	X	X	X	X	X	X	X	-	-	-	-	-
30	-	-	X	X	X	X	X	X	X	-	-	-	-	-
32	-	-	X	X	X	X	X	X	X	X	X	X	-	-
33	-	-	X	X	X	X	X	X	X	X	X	X	-	-
34	-	-	X	X	X	X	X	X	X	X	X	X	-	-
35	-	-	X	X	X	X	X	X	X	X	X	X	-	-
36	-	-	X	X	X	X	X	X	X	X	X	X	-	-
38	-	-	X	X	X	X	X	X	X	X	X	X	-	-
40	-	-	X	X	X	X	X	X	X	X	X	X	-	-
42	-	-	X	X	X	X	X	X	X	X	X	X	-	-
43	-	-	X	X	X	X	X	X	X	X	X	X	-	-
45	-	-	X	X	X	X	X	X	X	X	X	X	-	-
48	-	-	-	X	X	X	X	X	X	X	X	X	-	-
50	-	-	-	X	X	X	X	X	X	X	X	X	-	-
51	-	-	-	X	X	X	X	X	X	X	X	X	-	-
53	-	-	-	X	X	X	X	X	X	X	X	X	-	-
55	-	-	-	X	X	X	X	X	X	X	X	X	-	-
56	-	-	-	X	X	X	X	X	X	X	X	X	-	-
57	-	-	-	X	X	X	X	X	X	X	X	X	-	-
60	-	-	-	X	X	X	X	X	X	X	X	X	-	-
63	-	-	-	X	X	X	X	X	X	X	X	X	-	-
65	-	-	-	X	X	X	X	X	X	X	X	X	X	X
70	-	-	-	X	X	X	X	X	X	X	X	X	X	X
76	-	-	-	X	X	X	X	X	X	X	X	X	X	X
83	-	-	-	-	-	X	X	X	X	X	X	X	X	X
89	-	-	-	-	-	X	X	X	X	X	X	X	X	X
102	-	-	-	-	-	X	X	X	X	X	X	X	X	X

Unmeasured length of electric welded pipes Products can range from 1.5 to 9 m. The measured length should be in the range of 5-9 m.

Seamless stainless steel pipes are reliable products with wide application. Their cost is higher than that of welded analogues, which are more suitable for domestic use.

Have you ever dealt with seamless pipes? What grades of steel do you think are most in demand? Share your opinion in the comments.

Among the range of pipes offered by the Energocontrol company, there are products designed to solve a wide range of problems. For example, these are seamless pipes that are corrosion-resistant and designed for use in less-than-ideal conditions. Now, in order to find a supplier of a range of stainless pipes manufactured in accordance with GOST 9940-81, you do not have to surf the Internet, since you can always find on the company’s website up-to-date information and discover interesting offers.

Why is cooperation with Energocontrol LLC most preferable? Our company offers low prices and a wide range of products manufactured according to interstate standards. Stainless steel seamless pipes can be purchased both wholesale and retail buyers. The presence of our own warehouses located in St. Petersburg and Moscow, as well as the possibility of delivery to any region of Russia - this is truly profitable terms, available only from a few suppliers.

Status GOST 9940-81

This standard applies to corrosion-resistant, seamless pipes manufactured by hot deformation. The wall thickness of the products varies between 3.5-32 mm, and the diameter - 57-325 mm. As for the length, it should not deviate upward or downward by more than 15 mm, although manufacturers often manufacture products according to the parameters specified by the customer, but within the standard, with a multiplicity of 300 mm.

Hot-deformed pipe can be manufactured not only in accordance with GOST, but also in accordance with technical regulations. GOST 9940-81 is valid, and any steel grades that fall under their standard can be used in the manufacture of products.

Application area

Cold-deformed pipes are endowed with greater strength, but hot-deformed pipes are distinguished by ductility and flexibility, and if the pipe is made of steel 20x23n18, this means one thing: the product has increased heat resistance, therefore, it can be used to create structures that will be constantly exposed to ultra-high temperatures. Hot-rolled pipes in accordance with GOST 9940-81, made from less heat-resistant steel grades, but not devoid of increased corrosion resistance, can be used:

1. In mechanical engineering, shipbuilding and aircraft construction. Hot-rolled pipes are often used to make elements of engines, cooling systems and other units, inside of which there is a high risk of traces of corrosion, temperature and pressure changes.
2. In the nuclear industry. Corrosion-resistant steel is especially in demand in this area, as well as rolled pipes made from a material that combines a whole list of positive properties. This and increased stability to aggressive environments, high strength characteristics and lack weld, which is very important, since this completely eliminates the possibility of leakage of working solutions and other substances, often dangerous.
3. Chemical industry. You can distill any substances through seamless hot-rolled pipes without fear of leaks and other force majeure.
4. Energy and building sector. If the heating system is created using just such pipe rolling, then there is no doubt about its reliability. Products made from heat-resistant steel grades are ideal for the manufacture of high-pressure boilers, steam generators and other installations.
5. Other sectors of the economy. These include: oil and gas production and mineral processing, as well as food, light and processing industries.

GOST 9940-81

Group B62

INTERSTATE STANDARD

HOT-FORMED SEAMLESS PIPES FROM CORROSION-RESISTANT STEEL

Specifications

Seamless hot deformed tubes made of corrosion resistant steel. Specification

ISS 23.040.10
OKP 31,500

Date of introduction 1983-01-01

INFORMATION DATA

1. DEVELOPED AND INTRODUCED by the USSR Ministry of Ferrous Metallurgy

DEVELOPERS

V.P. Sokurenko (topic leader), L.G. Kovaleva, V.N. Rovensky, G.A. Gorovenko

2. APPROVED AND ENTERED INTO EFFECT by the Resolution State Committee USSR according to standards dated July 20, 1981 N 3445

Change No. 4 was adopted by the Interstate Council for Standardization, Metrology and Certification (protocol No. 17 of June 22, 2000)

The following voted to approve the change:

	State name	Name of the national standardization body
	The Republic of Azerbaijan	Azgosstandart
	Republic of Armenia	Armgosstandard
	Republic of Belarus	State Standard of the Republic of Belarus
	The Republic of Kazakhstan	State Standard of the Republic of Kazakhstan
	Republic of Kyrgyzstan	Kyrgyzstandard
	The Republic of Moldova	Moldovastandard
	Russian Federation	Gosstandart of Russia
	The Republic of Tajikistan	Tajikgosstandart
	Turkmenistan	Main State Inspectorate "Turkmenstandartlary"
	The Republic of Uzbekistan	Uzgosstandart
	Ukraine	State Standard of Ukraine

3. INSTEAD GOST 9940-72

4. REFERENCE REGULATIVE AND TECHNICAL DOCUMENTS

	Item number

5. The validity period was lifted according to Protocol No. 2-92 of the Interstate Council for Standardization, Metrology and Certification (IUS 2-93)

6. EDITION (February 2007) with Amendments No. 1, 2, 3, approved in June 1987, June 1988, August 1988, April 2001 (IUS 11-87, 9-88, 12-88, 7-2001)


This standard applies to seamless hot-formed pipes made of corrosion-resistant steel general purpose.

(Changed edition, Amendment No. 3).

1. ASSORTMENT

1. ASSORTMENT

1.1. Pipes are manufactured according to the outer diameter and wall thickness with the dimensions indicated in Table 1.

Table 1

Notes:

1. Pipes made of steel grades 08Х17Т, 15Х28, 12Х17, 10Х17Н13М2Т are manufactured with a diameter of no more than 219 mm; from steel grade 08Х17Н15М3Т - with a diameter of no more than 140 mm, size 159x9 mm; from steel grade 10Х23Н18 - with a diameter of no more than 168 mm; made of steel grades 08Х18Н12Б, 08Х22Н6Т, 08Х20Н14С2 - with a diameter of no more than 108 mm.

2. By agreement between the manufacturer and the consumer, it is allowed to manufacture pipes with dimensions not listed in Table 1.

3. The mass of 1 m of pipes, kg, is calculated using the formula

where is the nominal outer diameter, mm;

- nominal wall thickness, mm;

- metal density, g/cm, depending on the steel grade in accordance with Table 3.

4. Pipes with a diameter of 76 to 95 mm with a wall thickness of 3.5-4.0 mm, with a diameter of 133 to 152 mm with a wall thickness of 4.0-5.5 mm, with a diameter of less than 76 mm will be produced after mastering the equipment.

1.2. According to the length of the pipe they are made:

measured length - within the unmeasured limits, but not more than indicated in Table 1 with a maximum length deviation of +15 mm; by agreement between the manufacturer and the consumer, it is allowed to manufacture measuring pipes of a length greater than that specified in Table 1;

length, a multiple of the measured length - within the measured length with an allowance for each cut of 5 mm and with a maximum deviation along the entire length of +15 mm. Minimum multiple length - 300 mm;

limited length - within the specified length with a maximum length deviation of ±500 mm;

unmeasured length - from 1.5 to 10 m; by agreement between the manufacturer and the consumer, it is allowed to manufacture pipes longer than 10 m.

1.3. In a batch of pipes of unmeasured length, no more than 15% of pipes with a length of 0.75 to 1.5 m are allowed.

1.4. The maximum deviations for the outer diameter and wall thickness are indicated in Table 2.

table 2

Pipe sizes	Maximum deviations for manufacturing accuracy, %
		high
By outer diameter
By wall thickness, mm:
		12,5 -15,0
more than 8 to 20
	12,5 -15,0

1.5. Ovality should not take the diameter of the pipes beyond the maximum deviations.

1.6. The curvature of pipes in any section 1 m long should not exceed:

1.5 mm - for wall thickness up to 10 mm inclusive;

2 mm - with wall thickness over 10 to 20 mm inclusive;

4 mm - with wall thickness over 20 mm.

1.7. The ends of the pipes must be cut at right angles and cleared of burrs; chamfering is allowed when removing them. At the consumer's request, the ends of pipes with a wall thickness of more than 5 mm must have a chamfer for welding.

Examples of symbols

Pipe with an outer diameter of 76 mm, a wall thickness of 5 mm, normal manufacturing precision, unmeasured length, made of steel grade 08Х18Н10Т:

Pipe 765 - 08Х18Н10Т GOST 9940-81

Same, high precision manufacture (c), length multiple (cr) 1500 mm:

Pipe 76 in 5 in 1500 kr - 08Х18Н10Т GOST 9940-81

The same, standard manufacturing accuracy, measured length (m) 3000 mm:

Pipe 76 5 3000 m - 08Х18Н10Т GOST 9940-81

The same, normal manufacturing precision, measured length 3000 mm with remainder:

Pipe 76 5 3000 - 08Х18Н10Т GOST 9940-81

The same, high precision manufacturing (c), limited length (g) 3000 mm:

Pipe 76 in 5 in 3000 g - 08Х18Н10Т GOST 9940-81

2. TECHNICAL REQUIREMENTS

2.1. Pipes are manufactured in accordance with the requirements of this standard and according to technical regulations approved in in the prescribed manner, from steel grades indicated in Table 3, with a chemical composition in accordance with GOST 5632, with microadditives of rare earth metals.

The sulfur content in steel intended for the manufacture of pipes to be welded, as indicated in the order, must not exceed 0.020%.

Pipes are manufactured heat-treated or without heat treatment in accordance with the order.

(Changed edition, Amendment No. 1, 4).

2.2. The mechanical properties of the pipes must correspond to those indicated in Table 3.

Table 3

steel grade	Tensile strength, N/mm (kgf/mm)	Relative extension	Density, g/cm
	no less
08Х17Н15М3Т
08Х18Н10Т
08Х18Н12Б
08Х18Н12Т
08Х20Н14С2
10Х17Н13М2Т
12Х18Н10Т
12Х18Н12Т

Notes:

1. For pipes with a ratio equal to or less than 8, made of steel grades 04Х18Н10, 08Х20Н14С2, 10Х17Н13М2Т, 08Х18Н12Т, 10Х23Н18, 08Х18Н10, 08Х18Н10Т, 08Х17Н15М3Т, 12Х18Н10Т, 12 Х18Н12Т, 12Х18Н9, 17Х18Н9, 08Х22Н6Т, it is allowed to reduce the tensile strength by 19.6 N/ mm(2 kgf/mm).

2. At the request of the consumer, for pipes made of steel grades 12Х18Н10Т, 12Х18Н12Т, 08Х18Н10Т, the yield strength is determined.

3. The yield strength for steel grade 12Х18Н10Т must be at least 216.0 N/mm (22 kgf/mm).

4. Yield strength standards for steel grades 12Х18Н12Т and 08Х18Н10Т are established by agreement between the manufacturer and the consumer.


(Changed edition, Amendment No. 1, 2, 3, 4).

2.3. At the customer's request, pipes must withstand a tensile test at a temperature of 623 K (350 °C).

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

(Changed edition, Amendment No. 1, 3).

2.4. Seals, flaws, sunsets, and cracks are not allowed on the outer and inner surfaces of pipes. It is allowed to remove defects by local grinding, continuous or local grinding, boring and turning, provided that the amount of boring, turning or continuous grinding does not take the diameter and wall thickness beyond the minus deviations, and local grinding or grinding does not bring the wall thickness beyond the minus deviations specified in Table 2.

Without cleaning, single spots, rippling, scratches, and traces of scale indentation are allowed, provided that they do not take the wall thickness beyond the minus maximum deviations.

At the request of the consumer, individual films must be cleaned.

(Changed edition, Amendment No. 2).

2.5. At the consumer's request, pipes are manufactured free of scale.

2.6. At the request of the consumer, pipes must withstand hydraulic pressure in accordance with the requirements of GOST 3845 at a permissible stress equal to 40% of the tensile strength for a given steel grade.

The ability of pipes to withstand hydraulic pressure is ensured by production technology.

2.7. At the request of the consumer, pipes made of steel grades 04Х18Н10, 08Х20Н14С2, 10Х17Н13М2Т, 08Х18Н12Б, 10Х23Н18, 08Х18Н10, 08Х18Н10Т, 08Х18Н12Т, 08Х17Н15М3Т, 12Х18Н10Т, 12Х18Н12Т, 12Х18Н9, 17Х18Н9, 08Х22Н6Т must withstand flattening until the distance between the surfaces is obtained (), mm, calculated by the formula

where is the nominal wall thickness, mm;

- nominal outer diameter, mm,

or expansion until the outer diameter increases by 10% using a mandrel with a taper angle of 30°; It is allowed to use mandrels with a taper angle of 6° and 12°.

2.8. At the request of the consumer, as indicated in the order, pipes made of steel grades 10Х17Н13М2Т, 08Х17Н15М3Т, 08Х22Н6Т, 04Х18Н10, 08Х18Н10, 08Х18Н10Т, 12Х18Н10Т, 12Х18Н9, 08Х18Н12Т, N12T, 08Х18Н12Б must be resistant to intergranular corrosion.

2.9. At the request of the consumer, pipes must undergo ultrasonic testing. The dimensions of the artificial defect are established by agreement between the manufacturer and the consumer.

3. ACCEPTANCE RULES

3.1. Pipes are accepted in batches. The batch must consist of pipes of the same size in diameter and wall thickness, the same grade of steel and one type of heat treatment, and at the request of the consumer - one heat, and is documented in one quality document in accordance with GOST 10692, with the addition: chemical composition - in accordance with the document about the quality of pipe blanks.

The number of pipes in a batch should be no more than 200 pieces.

3.2. Each pipe is subjected to surface, size, hydraulic pressure, and ultrasonic control.

3.3. For quality control, the following are selected from the batch:

two pipes - in tension;

one pipe - for flattening or distribution;

two pipes - for intergranular corrosion.

If unsatisfactory test results are obtained for at least one of the indicators, repeated tests are carried out on a double number of pipes selected from the same batch.

The results of repeated tests apply to the entire batch.

(Changed edition, Amendment No. 4).

3.4. (Deleted, Amendment No. 4).

4. TEST METHODS

4.1. For quality control, one sample is cut from each selected pipe for each type of test.

4.2. Inspection of the pipe surface is carried out visually.

4.3. The length of the pipes is checked with a tape measure according to GOST 7502..

4.6. The tensile test is carried out according to GOST 10006, GOST 19040 (at a temperature of 623 K).

The moving speed of the movable gripper is no more than 10 mm per minute. It is allowed to exceed the test speed by up to 40 mm per minute after reaching the yield point.

Control allowed mechanical properties carried out using the hardness method according to regulatory and technical documentation.

In case of disagreement in assessing the results, tests are carried out according to GOST 10006.

(Changed edition, Amendment No. 1).

4.7. The expansion test is carried out on pipes with a diameter of up to 146 mm inclusive with a wall thickness of no more than 10 mm according to GOST 8694.

(Changed edition, Amendment No. 1).

4.8. The flattening test is carried out on pipes with a wall thickness of no more than 10 mm according to GOST 8695.

If small defects are detected on flattened samples that are a consequence of external defects that are allowed without cleaning, the sample from the same pipe is retested with preliminary cleaning of the surface to a depth of half the maximum deviations in wall thickness, but not more than 0.2 mm from the side on which defects found.

4.9. Hydraulic pressure testing is carried out in accordance with GOST 3845 with the pipes held under pressure for at least 10 s.

4.9.1. Instead of testing with hydraulic pressure, it is allowed to inspect each pipe using non-destructive methods in accordance with GOST 17410 and normative and technical documentation from 01.01.90.

(Introduced additionally, Amendment No. 1).

4.10. Ultrasonic testing is carried out in accordance with GOST 17410 and regulatory and technical documentation.

4.11. Testing of resistance to intergranular corrosion is carried out using AM or AMU methods according to GOST 6032. In case of disagreement in the assessment of results, verification is carried out using the AM method.

By agreement between the manufacturer and the consumer, testing the resistance to intergranular corrosion of steel grades 12Х18Н10Т and 08Х18Н10Т can be carried out using the PT method according to GOST 9.914. In case of disagreement in the assessment of the results, the verification is carried out using the AM method according to GOST 6032.

(Changed edition, Amendment No. 4).

5. LABELING, PACKAGING, TRANSPORTATION AND STORAGE

5.1. Labeling, packaging, transportation and storage - in accordance with GOST 10692.



Electronic document text
prepared by Kodeks JSC and verified against:
official publication
M.: Standartinform, 2007

A stainless steel pipe, all requirements for parameters of which are specified by GOST, is the optimal choice for the installation of pipelines transporting liquid and gaseous media with high chemical aggressiveness. There is a great need for such pipelines in many industries - chemical and petrochemical, general and nuclear engineering, thermal energy, equipment of water vessels, etc.

Requirements of GOST 9941-81

You can familiarize yourself with the GOST requirements for cold- and heat-deformed stainless steel pipes by downloading the document in pdf format from the link below.

GOST 9941-81 Cold- and heat-deformed seamless pipes made of corrosion-resistant steel. Specifications

GOST 9941-81 specifies the requirements for pipes round section, which are made from general purpose materials. Under action of this document includes seamless pipes produced using cold and warm deformation technology. GOST 9941-81 indicates that stainless pipes of this type can be produced in the range of outer diameters of 5–273 mm and with a wall thickness in the range of 0.2–22 mm.

They determine the GOST requirements and the length of stainless steel pipes of this category, which can be measured, in the range of 5–7 meters, as well as unmeasured and multiple measured. At the request of customers and in agreement with the manufacturer, it is possible to manufacture such products in a wider range of lengths - 0.5–16 meters.

GOST allows the presence in a general batch of pipes of unmeasured length of products whose length is in the following ranges:

It should be borne in mind that the number of pipes with specified parameters cannot exceed 6% of the volume of the entire batch in which they are present.

Depending on the degree of compliance of the geometric parameters of corrosion-resistant pipes with the values ​​specified in GOST, such products can be classified into one of three categories: normal, high and increased accuracy. For each of these categories, the standard specifies maximum deviations in wall thickness. Yes, for different categories GOST pipe rolling stipulates the following tolerance values:

In terms of the outer diameter of round pipes made of stainless steel, GOST also stipulates the following deviations:

For pipes with a diameter greater than 30 mm, made of stainless steel grade 06ХН28МДТ, the maximum deviation of the outer diameter is 1.2%.

Parameters of cold- and heat-deformed pipes

Stainless steel ends steel pipes, made using cold or hot deformation technology, are cut at an angle of 90°, and burrs must be removed from the cut ends. GOST allows that when deburring the cut ends of pipes, chamfers can be formed. Moreover, on steel pipes whose wall thickness exceeds 5 mm, chamfers are often made specifically at the customer’s request, allowing for more efficient and high-quality installation using welding.

The provisions of GOST for rolled pipes made of stainless steel also stipulate such a parameter as the curvature of the surface, measured over a length not exceeding 100 cm. Depending on the thickness of the pipe wall and its outer diameter, this parameter should not exceed the following values:

It should be borne in mind that GOST does not stipulate the maximum value of the surface curvature of stainless steel pipes if the outer diameter of such products is less than one and a half centimeters and the wall thickness does not exceed half a millimeter. It is important that the surface of such pipes does not have sharp bends, and their ovality, if present, does not lead to the outer diameter of the product exceeding the deviations allowed by GOST.

The most common steel grades from which pipes of this category are produced are:

• 08ХН28МДТ;
• 12Х18Н10;
• 12Х18Н10Т;
• 12Х18Н12Т;
• 08Х19Н10Т;
• 10Х23Н18;
• 10Х17Н13М2Т;
• 04Х18Н10;
• 12X17;
• 08Х13;
• 08Х22Н6Т;
• 15Х25Т;
• 12X13;
• and other grades of steels belonging to the high-alloy category.

GOST also stipulates the following parameters for the material used to manufacture pipe products:

• density – 7.7–7.96 g/cm3;
• relative elongation value – 17–45%;
• temporary resistance – 38–588 kgf/mm 2.

If speak about chemical composition steels used for the production of rolled pipes of this category, then it may contain a small amount of materials belonging to the rare earth group, and the presence of such harmful impurities as sulfur should not exceed two hundredths of a percent.

Table 5. Content of alloying elements and compliance with stainless steel standards (click to enlarge)

In the standard version, stainless steel pipes of this category are subjected to heat treatment, but GOST allows that, by agreement with the customer, such treatment may not be carried out. In cases where heat treatment of pipes of this category is not performed, the degree of their permissible curvature and mechanical characteristics are also discussed separately.

GOST also regulates the condition of the external and internal surfaces of pipes made from. According to these requirements, such surfaces should be free of defects - spots, cracks and plains. If these defects are present, then they can be corrected, which should not lead to a reduction in the permissible dimensions of the pipes, such as wall thickness and outer diameter. In this case, you can correct detected defects using following methods processing:

• grinding, which can be applied to individual areas, as well as the entire surface of the pipe;
• turning;
• boring;
• mechanical cleaning of problem areas.

Although GOST states that the surface of pipes made of stainless steels should have a light metallic sheen, it is allowed to have matte areas characterized by a gray color. To defects in stainless steel pipes, which are specified by the provisions normative document, also does not include painting individual areas in tarnished colors. This assumption is acceptable if etching, performed in a vacuum or in a protective environment, was not used as a finishing process.

Provisions of GOST 9940-81

You can familiarize yourself with the GOST requirements for hot-deformed stainless steel pipes by downloading the document in pdf format from the link below.

GOST 9940-81 Seamless hot-deformed pipes made of corrosion-resistant steel. Specifications

GOST 9940-81 contains requirements for seamless stainless steel pipes, which are manufactured using hot deformation technology. GOST 9940-81 also regulates not only the characteristics of tubular products, but also their range, according to which they can be produced in the range of outer diameters of 57–325 mm and with wall thicknesses in the range of 3.5–32 mm. Pipes that fall under the requirements of the mentioned standard are made from the same grades of steel as the above-described pipe products.

The two above-mentioned GOSTs are almost identical in most of the requirements for stainless steel tubular products, so it is not advisable to consider GOST 9940 separately.

It is also worth mentioning the acceptance of finished pipes made of stainless steel. In this case, it is not a single pipe that is tested, but a batch of products that differ in identical characteristics (grade of steel used, geometric parameters, type of heat treatment applied, etc.). The tested batch may contain no more than 200 units of the same type. Individual products from the tested batch of stainless pipes are tested for...

STATE STANDARD OF THE USSR UNION

Date of introduction 01.01.83

This standard applies to seamless hot-formed corrosion-resistant steel pipes for general purposes.

(Changed edition, Amendment No. 3).

1. ASSORTMENT

1.1. Pipes are manufactured according to the outer diameter and wall thickness of the dimensions specified in.

1.2. According to the length of the pipe they are made:

measured length - within unmeasured limits, but not more than specified with a maximum deviation in length + 15 mm; by agreement between the manufacturer and the consumer, it is allowed to manufacture measuring pipes of a length greater than that specified in;

length, a multiple of the measured length - within the measured length with an allowance for each cut of 5 mm and with a maximum deviation along the entire length + 15 mm. Minimum multiple length 300 mm;

limited length - within the specified length with maximum deviation along the length ± 500 mm;

unmeasured length - from 1.5 to 10 m; by agreement between the manufacturer and the consumer, it is possible to manufacture pipes longer than 10 m.

Outer diameter, mm	Length of measuring pipes, m, no more, with wall thickness, mm
	3,5	4	4,5	5	5,5	6	6,5	7	7,5	8	8,5	9	9,5	10	11	12	13	14	15	16	17	18	19	20	22	24	25	26	28	30	32
57			By agreement with the manufacturer consumer
60
68
73
76
83															By agreement between the manufacturer and the consumer
89
95
102
108
114
121
127
133
140
146
152
159																														By agreement between the manufacturer and the consumer
168															7	6,5	6,5	6,5	6	6	5,5	5,5	5	4,5	4,5	4,5	3	3
180	-	-	-	-	-	-	-	-	-	8	8	7,5	7,5	7	7	6,5	6,5	6,5	6	6	5,5	5,5	5	4,5	4,5	4,5	4	3,5	3,5
194	-	-	-	-	-	-	-	-	-	-	-	8	7,5	7	7	6,5	6,5	6,5	6	6	5,5	5,5	5	4,5	4,5	4,5	4	3,5	3,5
219	-	-	-	-	-	-	-	-	-	-	-	-	-	8	8	7,5	7,5	7	6,5	6,5	5,5	5,5	5	4,5	4,5	4,5	4	3,5	3,5
245	-	-	-	-	-	-	-	-	-	-	-	-	-	-	8	8	7,5	7	7	6,5	6	5,5	5	4,5	5	4,5	4,5	-	-	-	-
273	-	-	-	-	-	-	-	-	-	-	-	-	-	-	8	8	7,5	7	6,5	6	5,5	5,5	5	4,5	-	-	-	-	-	-	-
325	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-	6,5	6	5,5	5	5	-	-	-	-	-	-	-	-	-	-	-

Notes:

1. Pipes made of steel grades 08Х17Т, 15Х28, 12Х17, 10Х17Н13М2Т are manufactured with a diameter of no more than 219 mm; made of steel grade 08Х17Н15М3Т - with a diameter of no more than 140 mm, size 159´ 9 mm; from steel grade 10Х23Н18 - with a diameter of no more than 168 mm; made of steel grades 08Х18Н12Б, 08Х22Н6Т, 08Х20Н14С2 - with a diameter of no more than 108 mm.

2. By agreement between the manufacturer and the consumer, it is allowed to manufacture pipes with dimensions not specified in.

3. The mass of 1 m of pipes, kg, is calculated using the formula

,

WhereD n - nominal outer diameter, mm;

s - nominal wall thickness, mm;

- metal density, g/cm 3, depending on the steel grade in accordance with.

4. Pipes with a diameter of 76 to 95 mm with a wall thickness of 3.5 - 4.0 mm, with a diameter of 133 to 152 mm with a wall thickness of 4.0-5.5 mm, with a diameter of less than 76 mm will be produced after mastering the equipment.

1.3. In a batch of pipes of unmeasured length, no more than 15% of pipes with a length of 0.75 to 1.5 m are allowed.

1.4. The maximum deviations for the outer diameter and wall thickness are indicated in table. 2.

Pipe sizes	Maximum deviations for manufacturing accuracy, %
	ordinary	high
By outer diameter	± 1,5	± 1,0
By wall thickness, mm:
8 or less	+20,0	+12,5
	-15,0	-15,0
more than 8 to 20	± 15,0	+12,5
		-15,0
more than 20	+12,5
	-15,0	± 12,5

1.5. Ovality should not take the diameter of the pipes beyond the maximum deviations.

1.6. The curvature of pipes in any section 1 m long should not exceed:

1.5 mm - for wall thickness up to 10 mm inclusive;

2 mm - with wall thickness over 10 to 20 mm inclusive;

4 mm - with wall thickness over 20 mm.

1.7. The ends of the pipes must be cut at right angles and cleared of burrs; chamfering is allowed when removing them. At the consumer's request, the ends of pipes with a wall thickness of more than 5 mm must have a chamfer for welding.

Examples of symbols

Pipe with an outer diameter of 76 mm, a wall thickness of 5 mm, normal manufacturing precision, unmeasured length, made of steel grade 08Х18Н10Т:

Pipe 76´ 5 - 08Х18Н10Т GOST 9940-81

The same, high precision manufacturing (c), multiple length (cr) 1500 mm:

Pipe 76v´ 5v´ 1500cr - 08Х18Н10Т GOST 9940-81

The same, standard manufacturing accuracy, measured length (m) 3000 mm:

Pipe 76´ 5 ´ 3000m - 08Х18Н10Т GOST 9940-81

The same, normal manufacturing precision, measured length 3000 mm with remainder:

Pipe 76´ 5 ´ 3000 - 08Х18Н10Т GOST 9940-81

The same, high precision manufacturing (c), limited length (g) 3000 mm:

Pipe 76v´ 5v´ 3000og - 08Х18Н10Т GOST 9940-81

2. TECHNICAL REQUIREMENTS

2.1. Pipes are manufactured in accordance with the requirements of this standard and according to technical regulations approved in the prescribed manner, from steel grades specified in

15Х28

441(45)

17

7,60

15Х25Т

441(45)

17

7,60

04Х18Н10

441(45)

40

7,90

10Х23Н18

491(50)

37

7,95

08Х17Н15М3Т

510(52)

35

8,10

08Х18Н10

510(52)

40

7,90

08Х18Н10Т

510(52)

40

7,90

08Х18Н12Б

510(52)

38

7,90

08Х18Н12Т

510(52)

40

7,95

08Х20Н14С2

510(52)

35

7,70

10Х17Н13М2Т

529(54)

35

8,00

12Х18Н9

529(54)

40

7,90

12Х18Н10Т

529(54)

40

7,90

12Х18Н12Т

529(54)

40

7,95

17Х18Н9

568(58)

40

7,90

08Х22Н6Т

588(60)

24

7,60

Notes:

1. For pipes with ratioD n / S equal to or less than 8 from steel grades 04Х18Н10, 08Х20Н14С2, 10Х17Н13М2Т, 08Х18Н12Т, 10Х23Н18, 08Х18Н10, 08Х18Н10Т, 08Х17Н15М3Т, 12Х18Н10Т, 12Х18Н12Т, 12Х18Н9, 17Х18Н9, 08Х22Н6Т, it is allowed to reduce the tensile strength by 19.6 N/mm 2 (2 kgf/mm 2).

2. At the request of the consumer, for pipes made of steel grades 12Х18Н10Т, 12Х18Н12Т, 08Х18Н10Т, the yield strength is determined.

3. The yield strength for steel grade 12Х18Н10Т must be at least 216.0 N/mm 2 (22 kgf/mm 2).

4. Yield strength standards for steel grades 12Х18Н12Т and 08Х18Н10Т are established by agreement between the manufacturer and the consumer.

(Changed edition, Amendment No. 1, 2, 3, 4).

2.3. At the request of the consumer, pipes must withstand a tensile test at a temperature of 623 K (350 ° WITH).

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

(Changed edition, Amendment No. 1, 3).

2.4. Seals, flaws, sunsets, and cracks are not allowed on the outer and inner surfaces of pipes. It is allowed to remove defects by local grinding, continuous or local grinding, boring and turning, provided that the amount of boring, turning or continuous grinding does not take the diameter and wall thickness beyond the minus deviations, and local grinding or grinding does not bring the wall thickness beyond the minus deviations specified V .

Without cleaning, single spots, rippling, scratches, and traces of scale indentation are allowed, provided that they do not take the wall thickness beyond the minus maximum deviations.

At the request of the consumer, individual films must be cleaned.

(Changed edition, Amendment No. 2).

2.5. At the consumer's request, pipes are manufactured free of scale.

2.6. At the request of the consumer, pipes must withstand hydraulic pressure P 1 in accordance with the requirements of GOST 3845 at a permissible stress equal to 40% of the tensile strength for a given steel grade.

The ability of pipes to withstand hydraulic pressure is ensured by production technology.

2.7. At the request of the consumer, pipes made of steel grades 04Х18Н10, 08Х20Н14С2, 10Х17Н13М2Т, 08Х18Н12Б, 10Х23Н18, 08Х18Н10, 08Х18Н10Т, 08Х18Н12Т, 08Х17Н15М3Т, 12Х18Н10Т, 12Х18Н12Т, 12Х18Н10, 17Х18Н9, 08Х22Н6Т must withstand flattening until a distance is obtained between the surfaces ( N), mm, calculated by the formula

Where s- nominal wall thickness, mm;

D- nominal outer diameter, mm,

or expansion until the outer diameter increases by 10% using a mandrel with a taper angle of 30 ° ; It is allowed to use mandrels with a taper angle of 6 and 12 ° .

2.8. At the request of the consumer, as indicated in the order, pipes made of steel grades 10Х17Н13М2Т, 08Х17Н15М3Т, 08Х22Н6Т, 04Х18Н10, 08Х18Н10, 08Х18Н10Т, 12Х18Н10Т, 12Х18Н9, 08Х18Н12Т, N12T, 08Х18Н12Б must be resistant to intergranular corrosion.

2.9. At the request of the consumer, they must undergo ultrasound control. The size of the artificial defect is determined by agreement between the manufacturer and the consumer.

3. ACCEPTANCE RULES

3.1. Pipes are accepted in batches. The batch must consist of pipes of the same size in diameter and wall thickness, one grade of steel and one type of heat treatment, and at the request of the consumer - one melt and be issued with one quality document for the pipe blank.

The number of pipes in a batch should be no more than 200 pieces.

3.2. Each pipe is subjected to surface, size, hydraulic pressure, and ultrasonic control.

3.3. For quality control, the following are selected from the batch:

two pipes - in tension;

one pipe - for flattening or distribution;

two pipes - for intergranular corrosion.

If unsatisfactory test results are obtained for at least one of the indicators, repeated tests are carried out on a double number of pipes selected from the same batch.

The results of repeated tests apply to the entire batch.

(Changed edition, Amendment No. 4)

3.4. Deleted (Change No. 4)

4. TEST METHODS

4.1. For quality control, one sample is cut from each selected pipe for each type of test.

4.2. Inspection of the pipe surface is carried out visually.

4.3. The length of the pipes is checked with a tape measure according to GOST 7502.

(Changed edition, Amendment No. 4)

4.4. The curvature of the pipes is checked with a straight edge in accordance with GOST 8026 and a feeler gauge according to regulatory documentation.

(Changed edition, Amendment No. 3, 4).

4.5. The outer diameter and ovality are controlled with a smooth micrometer type MK in accordance with GOST 6507, sheet staples in accordance with GOST 18360, GOST 18365.

The wall thickness is controlled with a pipe micrometer type MT according to GOST 6507.

(Changed edition, Amendment No. 4)

4.6. The tensile test is carried out according to GOST 10006, GOST 19040 (at a temperature of 623 K).

The moving speed of the movable gripper is no more than 10 mm per minute. It is allowed to exceed the test speed by up to 40 mm per minute after reaching the yield point.

It is allowed to control the mechanical properties using the hardness method according to the normative and technical documentation.

In case of disagreement in assessing the results, tests are carried out according to GOST 10006.

(Changed edition, Amendment No. 1).

4.7. The expansion test is carried out on pipes with a diameter of up to 146 mm inclusive with a wall thickness of no more than 10 mm according to GOST 8694.

(Changed edition, Amendment No. 1).

4.8. The flattening test is carried out on pipes with a wall thickness of no more than 10 mm according to GOST 8695.

If small defects are detected on flattened samples that are a consequence of external defects that are allowed without cleaning, the sample from the same pipe is retested with preliminary cleaning of the surface to the depth of maximum deviations in wall thickness, but not more than 0.2 mm from the side on which they were found defects.

4.9. Hydraulic pressure testing is carried out in accordance with GOST 3845 with the pipes held under pressure for at least 10 s.

4.9.1. Instead of testing with hydraulic pressure, it is allowed to inspect each pipe using non-destructive methods in accordance with GOST 17410 and normative and technical documentation from 01.01.90.

(Introduced additionally, Amendment No. 1).

4.10. Ultrasonic testing is carried out in accordance with GOST 17410 and regulatory and technical documentation.

4.11. Testing of resistance to intergranular corrosion is carried out using the AM or AMU methods according to GOST 6032. In case of disagreement in the assessment of the results, the test is carried out using the AM method.

By agreement between the manufacturer and the consumer, testing the resistance to intergranular corrosion of steel grades 12Х18Н10Т and 08Х18Н10Т can be carried out using the PT GOST 9.914 method. In case of disagreement in the assessment of the results, the verification is carried out using the AM method according to GOST 6032.

(Changed edition, Amendment No. 4)

5. LABELING, PACKAGING, TRANSPORTATION AND STORAGE

5.1. Labeling, packaging, transportation and storage - in accordance with GOST 10692.

INFORMATION DATA

1. DEVELOPED AND INTRODUCED Ministry of Ferrous Metallurgy of the USSR

DEVELOPERS

V.P. Sokurenko(topic leader), L.G. Kovaleva, V.N. Rovensky, G.A. Gorovenko

2. APPROVED AND PUT INTO EFFECT Resolution of the USSR State Committee on Standards dated July 20, 1981 No. 3445

3. Inspection frequency - 5 years

4. INSTEAD GOST 9940-72

5. REFERENCE REGULATIVE AND TECHNICAL DOCUMENTS

6. The validity period has been lifted according to the Protocol of the Interstate Council for Standardization, Metrology and Certification (IUS 2-93)

7. REISSUE with Amendments No. 1, 2, 3,4, approved in June 1987, June 1988, August 1988, April 2001. (IUS 11-87, 9-88, 12-88, 7-2001 )