Stainless steel pipe - types, scope, GOST requirements

A stainless steel pipe is one of the most popular rolled metal products with a circular hollow section. These elements of rolled metal are produced, as a rule, from carbon steel of ordinary quality. In the manufacture of such a pipe, chromium or manganese impurities may be added. Thanks to these chemical elements, the strength of the pipe increases, the ability to weld is increased and its service life is significantly increased.

The production of such metal products is carried out using hot-dip galvanizing. The protective layer covers both the outside and the inside of the pipe.

When choosing a stainless pipe, first of all, factors such as the nature of the section, the type of joint welding, the steel grade and the quality of the finish are taken into account. Depending on the type of cross-section, the pipe can be round or shaped. The profile is square, oval, rectangular, depending on what shape the metal profile was used. Oval and square stainless pipes are often used in construction, but perhaps the most common shape is rectangular, which is indispensable for laying water pipes, in the construction and food sectors.

Pipe production methods

Stainless steel pipes are a derivative of rolled metal products. Based on the production method, the following types of stainless steel pipes are distinguished:

• Hot deformed;
• Cold-deformed;
• Heat-deformed;

Products can be produced from flat-rolled products, which are subjected to technological bending and subsequent welding. In this way, welded pipes are obtained. For seamless pipes, a stainless circle is used as the starting material, and in this case, piercing, rolling and calibration are used in the manufacture of the pipe. Seamless stainless steel pipe as a single piece has increased strength and high mechanical properties.

Standards

What standard a pipe is made to depend primarily on the method of its manufacture. The pipe production technology itself has already been covered many times, and we will not focus our attention on it; we will only mention the main points.

Welded pipes

Stainless pipes: GOST11068-81 are produced from flat billets. A narrow endless tape is formed from it, which is wound on a drum and fed to the line as required.

There, the future pipe is bent into a cylinder, the edges of which are welded using one of several methods:

• High frequency currents;
• Electric arc in an inert gas environment;
• Laser;
• Plasma;
• Electron beams.

The latter method is used extremely rarely due to its high cost: all technological operations take place in a vacuum.

The assortment determined by GOST includes pipes from 8 to 102 mm with walls from 0.8 to 4 mm thick.

Seam quality control is an obligatory stage in the production of welded pipes

Seamless pipes

The raw material for them is a round billet obtained by casting or pressing. Production includes several stages of processing with rollers: the pipe acquires the required diameter and wall thickness, calibrated, and then cut into pieces of the required length.

According to the temperature at which the workpiece is processed by the rollers, they are distinguished:

• Cold-deformed pipes;
• Heat-deformed;
• Hot deformed.

Cold-deformed and heat-deformed pipes GOST 9941 81 are manufactured with an outer diameter from 5 to 273 mm and a wall thickness from 0.2 to 22 mm.

Stainless pipe: GOST 9941-81 has the following permissible deviations from the specified dimensions:

For hot-deformed pipes, a different standard is used: they are produced in accordance with GOST 9940 81. They provide pipe sizes from 57 to 325 millimeters with a wall thickness of 3.5 to 32 mm.

Important: the actual production of pipes is not limited by the standard. By agreement with the customer, no one bothers to release, say, a thicker-walled or large-diameter pipe.

This standard also limits the maximum permissible deviations:

Before us is a blank for a seamless pipe. She has a long way to go through countless rollers

Classification

Stainless steel pipes differ in geometric characteristics depending on the diameter and shape of the pipe section, as well as the type of surface treatment. In cross-sectional shape, pipes can be round, square and rectangular. According to the type of processing, they are divided into:

• Matte
• Sanded
• Polished

The pipe wall thickness makes it possible to divide stainless pipes into thick-walled with high strength and thin-walled. Thin-walled pipes are characterized by high flexibility, therefore they are necessary for the manufacture of complex structures.

Grade steel for the manufacture of stainless pipes

The most popular steel grade is 12X18H10T, since it has maximum corrosion resistance. It uses as alloying additives: chromium, titanium and nickel. Most often, products made of such steel are used in the installation of plumbing systems for hot and cold water, since there are no harmful substances in the material that can harm the body of a person drinking this water.

Good mechanical stability prevents such substances from entering the system from the outside. According to state quality standards (GOST 9940), the elongation of pipes made of such steel should be at least 40%, and the tensile strength level should be 529 N / sq.mm.

The cross-sectional shape of such pipes determines the possible ways of their use. For example, non-circular products are suitable for the installation of various metal structures, for the manufacture of interior elements, as well as for finishing work in rooms for various purposes.

Other steel grades suitable for the manufacture of seamless pipes:

• 10Х17Н13М2Т: increased resistance to aggressive environments with high acidity, which is not lost even when thermally exposed to the material (up to 600 degrees Celsius). This steel grade is used most of all in the chemical, food and medical industries. Pipes made of this steel are easy enough to weld, thus obtaining a monolithic product with an extremely long operational life.
• 06ХН28МДТ: Ideal for solving the problems of the metallurgical and petrochemical industries. Again, the material is inert to acids, accompanied by heating to high temperatures.
• 10X23H18: one of the high-alloy steel grades that have unique resistance to high temperatures and open fire. Such steel is used to make chambers for fuel combustion, high-temperature pipelines, heating boilers and other equipment in which the body must withstand temperatures up to 1100 degrees Celsius.

Application of stainless steel pipes

Pipes today are indispensable in various fields: in the food industry, in mechanical engineering, in the petrochemical and mining industries, etc. They are used for laying utility lines and pipelines, transporting, among other things, aggressive gases and liquids.

Passat LLC supplies seamless and welded stainless steel pipes, round and profile sections.

The range includes stainless pipes of the following steel grades: AISI 201, AISI 202, AISI 304, AISI 321, AISI-316L, AISI-316Ti, AISI 409, AISI 430, various sizes (square from 20x20mm to 300x3000mm, rectangular from 10x20mm to 400x200mm, round diameter from 10mm to 300mm), and types of surface (polished, mirror, matte).

Scope and types

Depending on the section, stainless steel pipes are divided into:

• round;
• oval;
• square;
• rectangular.

According to the manufacturing method, they are:

• welded;
• seamless;
• hot rolled;
• heat-deformed;
• cold-drawn.

Also, stainless steel pipes differ in the type of surface, which can be:

• mirrored;
• matte.

Products are manufactured from complex alloyed steel grades containing a high percentage of chromium. It is he who forms a stainless protective layer on the surface that is resistant to aggressive factors and does not undergo corrosion, as well as oxidative processes.

Depending on the appearance and technical characteristics, GOST determines where and under what operating conditions certain stainless pipes should be used. They are most widely used in the construction and industrial sectors:

• chemical;
• automotive;
• instrumentation;
• food;
• medical;
• communal;
• furniture;
• fuel.

It is almost impossible to overestimate the importance of stainless pipe and list all the areas where it is used. It would be easier to name the industries in which it is not applied.

But there are some rules and restrictions on the use of certain types of pipes. For example, welded products are not intended for critical pipeline sections associated with high pressure or transportation of corrosive liquids and gases. Matt stainless pipes are not exposed, but are used in structures for which special aesthetic requirements are not imposed. The mirror surface of the products has decorative qualities, therefore they are widely used in furniture production and design work.

Profile pipes are not as widespread as round ones, but, nevertheless, they have found their application. They are used to make metal structures that are lightweight:

• frames;
• arches;
• farms;
• columns, etc.

Characteristics of electrowelded pipes

International standards: electrowelded pipes from austenitic steel grades ASTM A554, A270, A312, A249, A269, DIN 17457, 17455 Seam welding type - TIG, laser seam. Surface: • Matt • Sanded (180, 320, 400 Grit) • Mirror (400,600 Grit)

Symbols for determining the surface type of an electrowelded pipe

The form: • round • profile Length: 6m (delivery of pipes of any length is possible on request). Sizes: • diameter from 6 mm to 325mm • section from 10x10mm to 300x300mm, 400x200mm Wall thickness: from 0.8 mm to 6 mm

Types of stainless steel pipe connections

Seamless stainless steel pipes are connected by welding, which can be automatic, semi-automatic and manual. There are several technologies: TIG, HF and Laser. The first option is welding with a tungsten electrode in an inert gas environment. The resulting seam is characterized by density, uniformity, the absence of shells and voids. The strength of the welded seam is not inferior to the base material.

Note! The generator of heat, which is necessary for welding, is the arc formed between the workpiece and the electrode.Gas enters the welding zone from the inside and outside of the pipe, which protects the seam from oxidation.

HF - high-frequency current welding, which allows you to obtain a seam with slightly lower strength characteristics than that of the pipe body. This is due to the limited melting zone and the absence of a zone of thermal irritation, which leads to the heterogeneity of the seam. This technology is less expensive.

Laser welding technology preserves the strength characteristics of the TIG seam, and also reduces the melting zone, which results in a better surface treatment of the seam. This is important for pipes used in the chemical and food industries. Typically, laser welding is used in combination with TIG and plasma welding.

The popularity of seamless stainless steel pipes is explained by important operating parameters, extended temperature limits of their application, and high strength properties.

Fields of application of electrowelded pipes

• Heat exchangers and heaters • Decorations, structures • Oil and chemical industry • Food industry • Shipbuilding and mechanical engineering • Water transportation systems

Product standards according to intended use (stainless welded pipes)

How can you calculate the weight of a stainless steel pipe?

So, for the correct calculation, we will need the following values:

• specific gravity of a certain steel grade;
• product wall thickness;
• pipe diameter;
• footage (running meters).

Pipes of different sizes and lengths will have different weights

The first indicator, specific gravity, can be found in the table with typical data. It presents the characteristics of the most common variations in steel alloys.

Table 1

If you need to calculate the weight of a stainless steel pipe, you can take the indicator of the weight of a cubic meter of steel at 7.9 tons as a basis.

The wall thickness and diameter of the products can be found in the relevant GOSTs. An exception may be cases when pipes are not manufactured according to standard parameters, but according to the individual request of the customer.

The most common type of steel pipe is electrowelded products.

The most common types of steel pipes are electrowelded (physical dimensions are governed by the provisions of GOST 11068-81). The method of manufacturing such pipes is considered the simplest, therefore, electrowelded products have an optimal cost and are most often used in everyday life.

Important! The thickness of products made of alloys 04X17T and 0X18T1 is limited by a regulatory document: it is no more than 2 mm.

The existing sizes of such stainless pipes are presented in the table.

table 2

Having received all the necessary data, you can start calculating using the formula. The weight value is equal to the product of the volume of steel and the surface of the product. In order to more or less accurately find out the volume of the steel alloy in a given number of pipes, the wall thickness of the products is multiplied by the surface area indicator.The surface area, in turn, is determined by obtaining the product of the diameter of the stainless pipe, its length in meters and the constant pi (3.14).

To calculate the weight of a pipe, you need to measure its diameter, wall thickness and length

So let's take a look at a simple example. Suppose we have an abstract stainless pipe with the following dimensions: its diameter will be 100 millimeters, the wall thickness will be 2 millimeters, and the length of a single piece will be 10 meters. We make calculations in terms of meters.

Hence, the weight of such a structure will be as follows:

7900 (specific gravity of stainless steel) x 0.1 (diameter) x 10 (cut length) x 0.002 (wall thickness) x 3.14 = 49.612 kg.

This formula is correct in theory, but in practice it does not give as accurate results as we would like. The dimensions of the round pipe make it difficult to make a 100% correct calculation.

Further calculations will be made according to a simplified formula, which is based on the dimensions of the stainless steel pipe and the result of the mass obtained in the previous example:

Linear weight of stainless pipe = (outside diameter [in mm] - wall thickness [in mm]) x wall thickness [in mm] x 0.045 [rounded weight of steel in kg] = (D-T) x T x 0, 05.

So, in our case, the weight is 1 lm. steel pipes will be equal to:

(100-2) x 2 x 0.05 = 9.8 kg / running meter.

By the way, there are other formulas for calculating the weight of a running meter of types of stainless structures:

• stainless square profile: A (side size) x A x 0.0079 [kg];
• stainless rectangular profile: (B + A - 2S) x 0.0158 [kg] x S.

There are standard pipe sizes, you do not need to use formulas to calculate their weight

Seamless pipe characteristics

International standards:

• ASTM A312 - Seamless pipes (cold-smoked) from austenitic stainless steels,
• ASTM A213 - Seamless Ferritic and Austenitic Alloy Boilers,
• superheating and heat exchange tubes.

Surface: Matt The form: round Length: 5-7m Sizes: diameter from 6mm to 325mm Wall thickness: from 1mm to 13mm

Applications of seamless pipes

• Pipes of general purpose, chem. and nuclear industry • Heat exchangers • Stoves and chimneys

Dimensions and weight of stainless steel pipes according to GOST

19.10.2016
At the present time, stainless steel pipes are actively used in construction. Their diameter depends on several factors - the manufacturer's company, manufacturing method, wall thickness. In addition, it affects the parameters of the pipes and the purpose for which they will be used. Diameter is the length between the outer edges of the pipe. This distance is equal to two radii.

Such an indicator is measured in millimeters and is indicated by a special sign?. But, there is also the only exception - samples of GOST 3262-75 in modern industry are usually measured by the inner diameter. Such models are designated by the symbol Du.

What are the sizes of stainless pipes provided by state standards, the table will allow you to find out in detail.

It should be noted that according to GOST 8734-75, thin-walled and cold-worked pipes are distinguished. In the first case, models of such dimensions are produced - 2.5 x 0.3; 4.0 x 0.2; 10 x 4.0; 16 x 2.0; 20 x 3.0; 22 x 1.5; 38 x 1.0; 40 x 2.0; 60 x 1.8. As for hot-deformed samples, here the standard provides for the production of pipes, the parameters of which are - 23 x 5.0; 26 x 4.0; 40 x 5.0; 48 x 6.0; 57 x 2.8; 60 x 4.5; 68 x 4.0; 75 x 5.0; 85 x 9.0; 102 x 10; 120 x 6.0; 133 x 3.0 160 x 4.5; 180 x 10.

According to experts, it is best to use pipes with a standard diameter in production. The stainless steel pipe, the dimensions according to GOST of which belong precisely to this category, makes it possible to work as simply as possible. If you have information about what the diameter is, then you can select all the necessary elements without any problems - plugs, transitions, fittings, and so on. In addition, the diameter will allow you to calculate weight, size. The pipe is stainless, taking into account all these parameters, it will be as effective as possible.

If the same diameter is noted, then the throughput of stainless models will be an order of magnitude higher than in the case of steel samples. All pipes according to the current standard are divided into three large groups - small, medium and large.

The first category includes those models whose diameter exceeds 50, namely - 59, 89, 108, 114, 159. Pipes of medium diameter are already correspondingly large. As a rule, there are models with sizes - 219, 325, 377, 530. There are other samples, but they are not used so often for one reason or another. And finally, the dimensions of large diameter stainless pipes are 630,820,1220,1620. It should be noted that according to the standard, there are no restrictions. That is, it is quite realistic to purchase pipes of larger sizes than those listed above.

The weight of a running meter of a stainless pipe directly depends on the diameter. The mass is calculated, taking into account the grade of the metal used in the production. With information regarding the mass of the pipe, you can easily translate such data into length. The approximate weight of a running meter of stainless steel pipes is indicated in the corresponding GOST.

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Product standards according to the intended use (stainless seamless pipes)

Diameters of stainless pipes - GOST and size table

Pipes made of stainless steel alloys are actively used today for the installation of heating systems, water supply and sewerage systems. Choosing the diameters of stainless pipes according to a special table of sizes, you can successfully select such products for solving various problems.

For each type of stainless steel pipe, there are maximum permissible deviations from the parameters defined by the relevant standards.

All pipes for the production of which stainless steel is used are produced in strict accordance with the regulatory document. GOST specifies not only the chemical composition of the material of their manufacture, but also the technology of their production, size and assortment.

Classification options

The entire range of pipes made of stainless steel is divided into several categories. The parameters by which such a division is carried out are:

• design features (seam and seamless);
• production technology (cold rolled, cold drawn and hot rolled);
• cross-sectional shape (round and profile);
• wall thickness (thick-walled and thin-walled).

Corrosion-proof pipes of various sizes are actively used for the arrangement of communications through which cold and hot water is transported, as well as for the installation of sewer systems. Such pipes, differing in significant diameter, are successfully used for the installation of oil and gas trunk pipelines.

The ratio of the outer diameter to the inner diameter for thick-walled stainless pipes is in the range of 0.05-0.1

The high popularity of stainless steel pipe products is explained by a whole list of its advantages:

• exceptional durability;
• the ability to operate under high pressure;
• resistance even to significant temperature extremes;
• high plasticity;
• resistance to corrosion, demonstrated even when operated under constant exposure to corrosive environments.

It should also be noted that the minimum service life of stainless steel pipes is 10 years.

Main varieties

GOST stipulates, among other things, a range of stainless steel pipes, which includes products:

1. used for the transportation of liquid and gas media - water and gas pipelines;
2. covered with a special anti-corrosion compound;
3. differing in insignificant wall thickness and having threads at the ends (such steel pipes, the diameters of which may be different, also have a reduced weight);
4. produced using welding technologies and having longitudinal seams;
5. seamless, made by hot-rolled technology.

On each of the types of stainless pipes, the range and diameters of which are stipulated by GOST, you should dwell in more detail. Water and gas pipes

The diameter of pipes of this type, as indicated by GOST, can vary within a fairly wide range: 15–50 mm. Such stainless pipes, depending on what pressure they are intended for operation, are divided into lightweight, standard and reinforced.

Parameters of water and gas pipes

GOST stipulates that the ends of water and gas pipes must be cut at an angle of 90 °, and the welded seams on their surface must be completely welded and sealed. In accordance with the standard, there may be minor chips on the surface of such steel pipes, but in general, their walls should be smooth and free of cracks.

Read also: Welding mask special wm 400 reviews

Anti-corrosion coated pipes

These pipes, which are also listed in the stainless steel product range, are distinguished by the fact that they have a zinc coating on their surface, which provides additional corrosion resistance. In accordance with the regulatory document, they should not have areas uncoated with zinc, coating blisters, burrs and other defects.

The dimensions of the thread, if applied to the ends of such pipes, should not exceed 10 percent of the length of the product itself.

Thin-walled threaded pipes

Available in a variety of sizes, these pipes are used when it is necessary to repair or redesign the pipeline. Products of this type, which make it possible to obtain reliable and tight connections, are not thick-walled and are not produced with large cross-sectional dimensions.

Parameters of light series pipes made for thread

On the surface of hot-rolled pipes, which can be thick-walled, there are no welds, which gives such products a high tightness and allows them to withstand even very significant pressure. These products, the standard sizes of which are also stipulated in the assortment, are distinguished by the smoothness of the walls and the minimum coefficient of thermal expansion.

The most common areas of application for such pipes, the dimensions of which can vary within a fairly wide range, are:

• installation of highways for supplying cold and hot water;
• arrangement of sewerage systems;
• installation of heating systems and communications for other purposes.

Sizes of Seamless Hot Wrought Stainless Tubes

It should be borne in mind that both thin-walled and thick-walled tubular products produced by welding can be used to supply water used for technical purposes, and not for drinking or cooking.

Standard sizes

The list of standard sizes of stainless pipe products includes the following parameters:

• the size of the nominal bore - the inner diameter, which can vary within 10–150 mm (the larger this parameter, the higher the permeability of the pipes);
• thread sizes (in accordance with the requirements of the standard, this parameter can vary in the range of 3 / 8-6 inches);
• outer diameter, which, taking into account the dimensions of the welded seam, can vary in the range 17–156 mm;
• the outer diameter of steel pipes, which are made without the use of welded joints, is 16–159 mm.

Main dimensions of stainless steel pipes

Stainless steel pipes, depending on their type, are manufactured in accordance with the requirements of various regulatory documents:

• GOST number 3262-75 - water and gas pipelines;
• 10705-80 - obtained by welding;
• 20295-85 - designed for laying main pipelines.

Each of the above regulatory documents contains tables that indicate the assortment and standard sizes of such products.

Brands and guaranteed parameters

The tables contained in the regulatory documents for stainless steel pipes contain various parameters. In particular, from these tables, you can take information about the steel grades used for the production of such pipes.

Permissible deviations from dimensions must be within the values ​​indicated in the table.

Knowing the grade of the material from which the pipe is made allows you to get an idea of ​​which of its parameters are guaranteed. These include, in particular:

• A - mechanical characteristics of the steel used;
• B - its chemical composition;
• B - the ratio of the chemical composition and mechanical properties of the alloy used.