Stainless steel pipe: GOST 9941-81 and 9940-81, assortment

Seamless stainless steel pipes are rolled according to two standards: GOST 9941-81 and GOST 9940-81.

Seamless stainless steel pipes, heat-deformed and cold-deformed, are manufactured in accordance with GOST 9941-81 from corrosion-resistant steel. Hot-rolled seamless stainless steel pipes are produced in accordance with GOST 9940-81.

Stainless steel pipes are used in food production, and are also widely used when transporting aggressive media: salts, alkalis, acids. The absence of a longitudinal seam ensures the integrity and high strength of the pipes. These products are resistant to all kinds of deformations, such as bending or twisting.

Prices for stainless steel seamless pipes GOST 9941-81

The price varies depending on the wall thickness, please check the cost by calling 8

Steel grade AISI 321

The greatest demand is for seamless stainless steel pipes made from “food grade” steel. Imported steel AISI 321 is an analogue of Russian 12Х18Н10Т. This steel belongs to the class of chromium-nickel steels of the austenitic class.

Seamless pipes made of AISI 321 steel can withstand temperatures ranging from - 196 ° C to + 600 ° C under normal conditions, and when operating in aggressive environments, the temperature at which the operating condition will be maintained should not exceed 350 ° C.

Seamless pipes made of steel 12Х18Н10Т can be welded by any type of automatic or manual welding, which is due to the low carbon content in its composition.

The first digit in the name of steel indicates the percentage of carbon in it. 12Х18Н10Т contains 0.12% carbon. First of all, the difference between grade 12Х18Н10Т and other stainless steels is the presence of titanium “Ti” in its composition.

This element creates more stable compounds with carbon molecules than chromium. Alloying with titanium makes the alloy resistant to intergranular corrosion.

That is, alloys with titanium have a longer service life than other grades of stainless steel.

Assortment

According to current standards, seamless stainless steel pipes are produced according to the outer diameter and wall size (for diameter dimensions, see GOST 9941-81 and GOST 9940-81).

• Pipe length:
• According to the length of the pipe they are made:
• measure;
• multiple measure;
• limited length within the limits of measurement;
• LDL from 1.5 meters to 10 meters;

Cracks, films, sunsets, and flaws are not allowed on the inner and outer surface of a seamless stainless steel pipe. According to the standards, some of the defects can be removed by local grinding, grinding, turning or boring, if, as a result of the work carried out, the wall thickness or diameter does not go beyond minus deviations.

Test methods

The surface quality of metal products is assessed visually; a tape measure is used to check the length; the curvature of the segments is determined using a special straight edge or feeler gauge. To assess the diameter, ovality and wall thickness of tubular products, a micrometer is used, as well as sheet staples. Methods and scope of testing are determined by the requirements of state standards GOST 7502, TU 2-0Z4-225, GOST 8026, GOST 6507, GOST 10006, GOST 19040, GOST 8694, GOST 17410, GOST 60Z2, GOST 9.914.

The difference between pipes GOST 9940 and 9941

Seamless products are produced from steel 12Х18Н10Т in accordance with GOST 9940-81. It applies to hot-deformed pipe products made from corrosion-resistant general-purpose alloys.

Stainless steel pipes according to GOST 9940 are manufactured:

• with diameter (external) from 57 to 325 mm;
• with wall thickness from 3.5 to 32 mm;
• standard maximum length from 3 to 8.5 m

In terms of manufacturing precision, pipes are produced with normal and high precision. Other geometric dimensions and physical and mechanical properties, which are described below, determined GOST 9940 for pipes 12Х18Н10Т and other tolerances for wall thickness, diameter and curvature.

The chemical composition of steel for seamless products of this standard is subject to the same requirements as those produced according to GOST 9941. And their mass is calculated using the same formula. The requirements for the ends and surface of the pipes are also identical.

Products are manufactured in accordance with the submitted order, heat-treated or without heat treatment and resistant to intergranular corrosion.

At the request of the customer, pipes are subjected to the same tests as those produced in accordance with GOST 9941, and using similar methods and conditions for their conduct.

The only difference here is that for hot-deformed pipes according to GOST 9940, their heat treatment is not a prerequisite for achieving the required physical and mechanical properties and conducting the necessary tests. After all, the method of manufacturing these products already presupposes the necessary heat treatment, which cannot be said about cold- and heat-deformed products according to GOST 9941.

Hot-deformed ones have greater flexibility and ductility, but are significantly inferior to cold- and heat-deformed ones in terms of strength and resistance to the physical impact exerted on them.

In addition, for hot-deformed pipes 12Х18Н10Т with a diameter to wall thickness ratio equal to or less than 8, a reduction in tensile strength by 2 kgf/mm2 (19.6 N/mm2) is allowed.

GOST 9941 products must withstand the rated load regardless of the geometric parameters of their cross-section. Only the yield strength of hot-deformed pipes is the same - 22 kgf/mm2 (216 MPa).

But this is due to the fact that the same stainless alloy is used for manufacturing - 12Х18Н10Т.

Due to their greater strength, GOST 9941 pipes are manufactured with smaller wall thicknesses and diameters than products of the 9940 standard. If we compare, for example, products with a diameter of 273, then cold- and heat-deformed ones are produced with walls of 3–14 mm, and hot-deformed ones with walls of 11–20 mm .

Accordingly, the areas of application of GOST 9941 and 9940 products are somewhat different.

The first is used where high strength of the pipeline or product is needed with its relative lightness, and the second, when during the installation and operation of a stainless network or part, the flexibility and ductility of the pipe from which they are made is more important.

When preparing the text, materials from the site https://tutmet.ru were used

Source: https://rospnk.ru/truba-nerzhaveyushchaya/faq/otlichie-mezhdu-trubami-gostov-9940-i-9941.html

Formula for calculating mass

The provisions of GOST 9941-81 do not contain precise information about how much one linear meter of seamless stainless pipe weighs. This is explained by the fact that the requirements of this standard cover a range of seamless pipes, for the manufacture of which about 20 grades of general purpose stainless steel can be used.

Meanwhile, this GOST presents a formula, using which you can easily determine the specific gravity of a pipe with certain geometric parameters.

Formula for calculating the mass of a linear meter of pipe

For convenience, GOST provides the density values ​​of all steel grades from which pipes of this category are produced. In particular, for 12Х18Н10Т this parameter is 7.9 g/cm3. As an example, you can determine the weight of one linear meter of a seamless stainless steel pipe of a given grade:

M = 3.14/1000 × (50–4) × 4 × 7.9 = 4.56 kg.

Using the weight of one linear meter of stainless pipe, calculated using this formula, you can easily determine how much a product of a certain length will weigh. To do this, it is enough to multiply the resulting weight by the total length of the pipe.

Stainless steel seamless pipe according to GOST 9941-81

engages in the supply of rolled pipes manufactured in accordance with GOST 9941-81.

This offer will be of interest to all enterprises and individuals in need of such products, and not only residents of Moscow and St. Petersburg, where the company’s warehouses are located, but also other regions can act as buyers.

And all because it delivers purchased rolled metal throughout Russia.

Why is cooperation with Energocontrol LLC truly beneficial? This is facilitated not only by a wide assortment, the ability to transport orders, the presence of our own warehouses in Moscow and St. Petersburg, work with wholesale and retail customers, and reasonable prices for all product units sold. The fact is that the company cooperates with all major manufacturers of rolled metal products, and can offer a wide range of products, including stainless steel seamless pipes manufactured in full compliance with GOST 9941-81.

Prices for pipes according to GOST 9940 and 9941

Stainless steel pipe GOST 9941-81

Corrosion-resistant pipes are widely used in the energy, food and chemical industries, construction and design. Pipes made from steels that are resistant to electrochemical corrosion are also called stainless steel.

According to manufacturing technology, stainless steel pipes are divided into:

• hot-deformed seamless pipes GOST 4490 81;
• cold- and heat-deformed seamless (GOST 4491-81) and welded (GOST 11068-81).

Stainless steel pipe GOST 9941-81, as well as hot-deformed stainless pipe GOST 9940-81, is made from high-chromium steels of type 08Х13, 10Х13, 12Х13, 14Х17Н2; austenitic type 08Х18Н9Т, 12Х18Н10Т; austenitic heat-resistant type 20Х23Н18, 20Х25Н20С2, 06ХН28МТ; sparingly alloyed high-manganese types 10Х13Г18Д, 10Х14Г14Н4Т, 10Х14AG15, 12Х17Г9AN4.

Each alloying system has its own purpose: to work in solutions of acids and alkalis, organic acids, in an oxidizing atmosphere at temperatures up to 650-11000C; at negative temperatures down to -1960C, etc.

The general rule is the following: the more expensive nickel in the steel, the higher the properties and capabilities of the steel, but also the higher the price. Naturally, special areas of application of stainless steel pipes are indicated. Any of them can be successfully used as a decorative material.

The choice is determined only by the cost of the steel grade.

Stainless steel pipe GOST 9941-81: features of manufacturing technology

Features of the production of seamless steel and stainless steel pipes:

• hot-deformed - by piercing and rolling a pipe blank;
• cold-deformed - in addition to hot rolling - by drawing or cold rolling of a hot-rolled billet (sleeve).

Alloying affects the temperature-time parameters of deformation and the features of surface preparation before reduction.

Unlike hot-deformed pipes GOST 9940-81, cold-deformed pipes have a better surface condition, higher dimensional accuracy, a uniform fine-grained steel structure with fewer defects.

Stainless steel cold-deformed pipes must undergo heat treatment. Goals: removal of internal stresses (softening) after cold deformation and homogenization (leveling of composition and structure) of steel.

High-chromium ferritic class steels of type 14Х17 (AISI 430) are subjected to annealing at 740-7800С, chromium-nickel austenitic steels of type 12Х18Н10Т (AISI 321) are quenched in water from 1050-10800С.

For austenitic steels, high-temperature heating is necessary to increase resistance to intergranular corrosion (ICC).