Pipe size DN 20. Pipe sizes, pipe diameters

To date diameter tables steel pipes are relevant for the reason that in almost all areas of construction pipes from different types plastic and metal. In order to easily understand this variety of materials and learn how to combine them, we have developed regulations, type - tables of steel pipe diameters and their correspondence polymer pipes. To calculate the weight of a pipe or the length of a pipe, you can use a pipe calculator.

Table of diameters of steel and polymer pipes.

Nominal diameter(Dy, Dy) is the nominal size (in millimeters) of the internal diameter of the pipe or its rounded value, in inches.

Conditional pass represents the rounded nominal inside diameter size. It is always rounded only in big side. The nominal diameter of steel pipes is determined by GOST 355-52.

Symbols and GOSTs:

• DIN / EN - the main European standard for steel pipes according to DIN2448 / DIN2458
• Steel water and gas pipes - GOST 3262-75
• Electric-welded steel pipes - GOST 10704-91
• Seamless steel pipes GOST 8734-75 GOST 8732-78 and GOST 8731-74 (from 20 to 530 mm).

Classification of steel pipes by outer diameter (Dн).

Small outer diameter steel pipes used for construction plumbing systems in apartments, houses and other premises.

Average diameter steel pipes used for the construction of urban water pipelines, as well as in industrial systems collection of crude oil.

Large diameter steel pipes necessary for the construction of main gas and oil pipelines.

Pipe internal diameter standard.

There is a standard for the internal diameter of pipes, which is accepted in most countries of the world. The internal diameter of pipes is measured in millimeters. The following are the most common internal pipe diameters:

• 200, etc.

Inner diameter of steel pipes denoted by (Din). There is also a certain standard for the diameter of pipes, it is designated by the term “nominal bore (diameter)”. It is designated Dу.

Pipe inner diameter can be calculated using the following formula: Din = Dn - 2S.

A value such as the internal diameter of pipes allows an accurate calculation of the throughput capacity of various engineering communications. This parameter is standardized, therefore it significantly simplifies the work of designers.

All types of parameter

The section is standardized in several varieties:

1. The conditional passage is designated as Dy or Du. This parameter is calculated in millimeters or in inches for steel (then it is rounded).
2. The nominal diameter is essentially the same as the first parameter. It is marked as Dn/Dn.
3. The external size is designated by the letters Dh.
4. The internal diameter of steel pipes (D) and their polymer analogues is the most important value.

In addition to the given parameters, the material wall thickness (h) is also used in the calculations.

What is conditional passage

The nominal passage is approximately equal to the cross-section of the pipe clearance. When designing, it is calculated so that the network throughput is sufficient.

Note! The graduation of conditional values ​​is determined by the standard. They are calculated so that the system throughput from one pass to the next increases by 60/100%.

Their values ​​are regulated by GOST 28338/89 “Pipeline connections and their fittings. Rows of nominal dimensions." Below is the graduation from the document.

Decoding the concept

The term “conditional passage” was introduced to preserve the amount of space for communications, creating conditions for design calculations.

Note! The instructions mean by this concept the average working section rounded down/up to the values ​​of the standard series. However, the actual internal diameter of a pipe of 30 mm, etc., as a rule, is not equal to the nominal analogue.

So, for materials with an external dimension of 160 and a wall thickness of 8, the actual size inside is 144, with walls of 6 - 150. But in both cases the nominal dimension is 150.

True internal section

1. Real working space elements depends on the thickness of their walls.
2. In most cases, water and gas pipeline materials are marked according to internal space, other types - according to appearance.
3. Steel products, based on their production technology, have unchanged external dimensions.
4. To ensure the reliability of the water supply system operated during high blood pressure, the thickness of the walls of its elements must be increased. Based on this, their working size will differ from the nominal diameter.

For example, a network with an external indicator of 275 and a wall thickness of 9 has a true internal dimension of 257. And the nominal internal diameter PVC pipes— 250 mm, determined by the closest value of the standard series.

Below is a table of sizes of steel products and their correspondence to analogues. It will allow you to accurately select analogues when designing a combined system.

It shows, for example, that the internal diameter metal-plastic pipe 20 corresponds to a steel analogue with an outer dimension of 26.

Defining the Element Workspace

By accurately determining the permeability of parts, you can calculate the volume of substance transmitted by them through the network.

Calculation of communication permeability for cold water

How much substance it passes per unit time will determine the internal diameter of the pipe 25 mm.

Product availability depends on the following.

1. Her work space. If it is too small, the hydraulic resistance of the system walls and the flow will increase working environment will weaken.
2. Pressure in engineering communications.
3. Communication lengths. The more extended it is, the stronger the friction weakening the flow.
4. Degree of smoothness of the material. The higher it is, the faster the substance moves through the system.
5. The age of the elements, i.e. the volume of deposits on their walls. The price of a system made from used materials will be low, but the efficiency will also decrease.
6. The number of transitions in communication from one dimension to another, as well as turns.

For a household system, a simple formula can be applied. To calculate the optimal internal section elements, you need to know the water consumption, as well as the flow rate:

D=√(4-P-1000/π∙v).

Here:

• P denotes water flow;
• π=3.14;
• v is the speed of movement of the working medium, it is equal to 0.7/1.2 m/sec. in analogues with a cross section of up to 32 mm and 1.5/2 m/sec. products contain more than the stated value.

Heating analogues

When you want to install a heating system yourself, the required permeability of its elements should be calculated so that in winter all living rooms are heated evenly.

To calculate heating products, there is the following formula:

D=√(π∙Q)/(v∙Dt).

The symbols here mean:

• D is the desired value;
• the number π is 3.14;
• Q—thermal energy flow, in kW;

In general, the length of the pipe can be from 4 to 12 linear meters.

It must be said that the weight of a water and gas pipe directly depends on its dimensions, that is, on the length, on the thickness of the walls and on many other parameters, which, in particular, will be discussed below.

Important! Many metal rolling plants also accept private orders, so it is possible to purchase products with a length of 1.5 to 4 meters.

This product (GOST 3262-75) has such an indicator as conditional passage. It can be 6, 8, 10, 15, 20, 25 and so on up to 90 mm.

Assortment of this material It also varies in wall thickness. On this basis they distinguish:

• Light pipes;
• Ordinary;
• Reinforced.

As already mentioned, the weight of the water and gas pipe (GOST 3262-75) also depends on this parameter.

Below is a table of correspondence between wall thickness and some other product parameters.

Among other things, such products can be:

• Not galvanized or black;
• Galvanized.

It must be said that galvanized materials weigh about 3% more, since the minimum thickness of the coating is about 0.3 mm.

Both of them are welded, that is seamless pipes This type is not produced.

According to accuracy they are distinguished:

• Normal accuracy;
• Increased.

It must also be said that such products can have threads, and according to the method of applying them, the following types are distinguished:

• Without thread;
• Threaded;
• With rolled thread.

There are special markings for this on the surface of the products. For example, in the case of a cut thread, you can see the letter “P”, and for a rolled thread, the letter “H” is used.

Steel grades and tolerances

The classification given above is rather incomplete. It can be continued almost endlessly. Such a huge range is due to the large number of applications for steel pipes.

Among other classifications, there is another one - by diameter. Naturally, thinner or thicker pipes are used for different purposes. Today, the industry produces steel products with a diameter from 17 to 114 mm. In this case, the following indicators are considered normal error:

• For products with diameters from 17 mm to 48 mm, the normal error (tolerance) can be considered 0.4-0.5 mm;
• For materials with diameters from 60 to 114 mm, the normal error is considered to be 0.8-1% of the diameter.

On the wall this figure is 15%.

It must also be said that these tolerances are typical only for the following grades of steel:

• 0.8ps and 0.8kp;
• 15, 15ps, 15kp;
• 20, 20ps, 20kp;
• St1ps;
• St2ps;
• St3ps and St3kp.

Some technical requirements

All steel water and gas supply materials are manufactured according to technical standards and have GOST 3262-75, as noted earlier. Production is carried out from types of steel (GOST 380 and GOST 1050) without standardization of the chemical composition and all mechanical qualities.

If necessary, the ends of the pipes can be chamfered at an angle of 40 degrees at the manufacturer's factory. With this type of work, an end ring is left, the width of which lies in the range from 1 to 3 mm.

It must be said that chamfers are removed from products whose wall thickness is more than 5 mm.

In addition, at the customer's request, threads can be applied to both ends. The condition is a conditional passage, which should not be less than 1 cm.

Among other things, individual water and gas supply elements can be equipped with couplings (GOST 8944,8954,8965 or 8966). In this case, each water and gas steel pipe must be equipped with one coupling.

The surface of the products must not have cracks, blisters or dents. There should be no delamination, chips or burrs at the ends.

The following defects are allowed:

• Risks;
• Individual dents;
• Traces of stripping;
• A layer of scale that does not interfere with inspection;
• Some manufacturing defects, but only if they do not reduce the wall thickness to the minimum value in some places.

Below is a table of correspondence of some parameters of water and gas products.

table of correspondence

GOST 7502-98

GOST 8026-92

GOST 8694-75

GOST 8695-75

GOST 8944-75

GOST 8954-75

GOST 8965-75

GOST 8966-75

GOST 10006-80

GOST 10692-80

GOST 11358-89

GOST 18242-72

GOST 18360-93

6. The validity period was removed by Decree of the State Standard of November 12, 1991 N 1726

7. EDITION (May 2007) with Amendments No. 1, 2, 3, 4, 5, 6, approved in November 1977, December 1978, January 1987, May 1988, November 1989. , November 1991 (IUS 1-78, 2-79, 4-87, 8-88, 2-90, 2-92)

This standard applies to non-galvanized and galvanized welded steel pipes with cut or rolled cylindrical thread and without thread, used for water and gas pipelines, heating systems, as well as for parts of water and gas pipeline structures.

(Changed edition, Amendment No. 2, 3, 5).

1. ASSORTMENT

1. ASSORTMENT

1.1. Pipes are manufactured according to the dimensions and weight given in Table 1.

At customer's request light pipes series intended for thread rolling are manufactured according to the dimensions and weight given in Table 2.

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

1.2. The length of the pipe is made from 4 to 12 m:

measured or multiple measured length with an allowance for each cut of 5 mm and a longitudinal deviation over the entire length plus 10 mm;

of unmeasured length.

By agreement between the manufacturer and the consumer, up to 5% of pipes with a length of 1.5 to 4 m are allowed in a batch of unmeasured pipes.

Table 1

Dimensions, mm

table 2

Dimensions, mm

Notes:

1. For threads made by rolling on a pipe, its internal diameter is allowed to be reduced by up to 10% along the entire length of the thread.

2. The mass of 1 m of pipes is calculated at a steel density of 7.85 g/cm. Galvanized pipes are 3% heavier than non-galvanized pipes.

1.3. Maximum deviations in pipe sizes should not exceed those indicated in Table 3.

Table 3

Notes:

1. The maximum deviation in the positive direction for wall thickness is limited by the maximum deviations for the mass of the pipes.

2. Pipes of standard manufacturing precision are used for water supply, gas pipelines and heating systems. Pipes with increased manufacturing precision are used for parts of water and gas pipeline structures.

1.4. Maximum deviations in the mass of pipes should not exceed +8%.

At the request of the consumer, maximum deviations in mass should not exceed:

7.5% - for the party;

10% - for a separate pipe.

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

1.5. The curvature of pipes per 1 m length should not exceed:

2 mm - with nominal bore up to 20 mm inclusive;

1.5 mm - with a nominal bore over 20 mm.

1.6. Pipe threads can be long or short. The thread requirements must correspond to those specified in Table 4.

Table 4

1.7. Pipes with a nominal bore of 6, 8, 10, 15 and 20 mm are wound into coils at the consumer’s request.

Examples of symbols

An ordinary pipe, non-galvanized, of normal manufacturing precision, of unmeasured length, with a nominal bore of 20 mm, a wall thickness of 2.8 mm, without threads and without a coupling:

Pipe 20x2.8 GOST 3262-75

The same with the coupling:

Pipe M-20x2.8 GOST 3262-75

The same, measured length, with thread:

Pipe P-20x2.8-4000 GOST 3262-75

The same, with zinc coating, of unmeasured length, with thread:

Pipe Ts-R-20x2.8GOST 3262-75

The same, with zinc coating, custom length, with thread:

Pipe Ts-R-20x2.8-4000 GOST 3262-75

For pipes for rolling threads in symbol After the word “pipe” the letter N is indicated.

For pipes with long threads, the letter D is indicated in the symbol after the word “pipe”.

For pipes with increased manufacturing precision, the letter P is indicated in the symbol after the size of the nominal bore.

(Changed edition, Amendment No. 1).

2. TECHNICAL REQUIREMENTS

2.1. Pipes are manufactured in accordance with the requirements of this standard and according to technological regulations, approved in in the prescribed manner, made of steel according to GOST 380 and GOST 1050 without standardization mechanical properties and chemical composition.

Pipes for parts of water supply and gas pipeline structures are made of steel in accordance with GOST 1050.

2.2. At the request of the consumer, the ends of pipes to be welded with a wall thickness of 5 mm or more must be chamfered at an angle of 35°-40° to the end of the pipe. In this case, an end ring 1-3 mm wide should be left.

Delamination is not allowed at the ends of the pipes.

Individual dents, rippling, scratches, traces of stripping and other defects caused by the production method are allowed, if they do not take the wall thickness beyond the minimum dimensions, as well as a layer of scale that does not interfere with inspection.

On pipes made by furnace welding, it is allowed to reduce the outer diameter to 0.5 mm at the seam if there is a gentle thickening in this place along the inner diameter of no more than 1.0 mm.

2.5. At the request of the consumer, on pipes with a nominal bore of 20 mm or more, the burr on the inner surface of the pipe seam must be cut off or flattened, and the height of the burr or its traces should not exceed 0.5 mm.

At the request of the consumer, on pipes with a nominal bore of more than 15 mm, manufactured by furnace welding and hot reduction, a gentle thickening with a height of no more than 0.5 mm is allowed on the inner surface of the pipes in the weld area.

(Changed edition, Amendment No. 2, 3, 4, 5, 6).

2.6. The ends of the pipes must be cut at right angles. The bevel of the end is allowed to be no more than 2°. The remaining burrs should not exceed 0.5 mm. When removing burrs, the formation of blunting (rounding) of the ends is allowed. It is allowed to cut pipes in the mill line.

By agreement between the manufacturer and the consumer, burrs up to 1 mm are allowed on pipes with a nominal bore of 6-25 mm, manufactured by furnace welding.

(Changed edition, Amendment No. 4, 6).

2.7. Galvanized pipes must have a continuous zinc coating over the entire surface with a thickness of at least 30 microns. The absence of zinc coating on the ends and threads of pipes is allowed.

On the surface of galvanized pipes, bubbles and foreign inclusions (hardzinc, oxides, sintered mixture), and peeling of the coating from the base metal are not allowed.

Individual flux spots and traces of pipes being caught by lifting devices, roughness and minor local deposits of zinc are allowed.

It is allowed to correct individual non-galvanized areas on 0.5% of the outer surface of the pipe in accordance with GOST 9.307.

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

2.8. Pipes must withstand hydraulic pressure:

2.4 MPa (25 kgf/cm) - ordinary and light pipes;

3.1 MPa (32 kgf/cm) - reinforced pipes.

At the request of the consumer, the pipes must withstand a hydraulic pressure of 4.9 MPa (50 kgf/cm).

2.9. Pipes with a nominal bore up to 40 mm inclusive must withstand the bend test around a mandrel with a radius equal to 2.5 outer diameters, and with a nominal bore of 50 mm - on a mandrel with a radius equal to 3.5 outer diameters.

At the request of the consumer, pipes must withstand the distribution test:

for pipes with a nominal bore from 15 to 50 mm - no less than 7%;

for pipes with a nominal bore of 65 mm or more - no less than 4%.

At the request of the consumer, pipes must withstand the flattening test to a distance between flattened surfaces equal to 2/3 of the outer diameter of the pipes.

2.8, 2.9. (Changed edition, Amendment No. 2, 3, 5).

2.10. At the request of the consumer, the mechanical properties of pipes for parts of water supply and gas pipeline structures must comply with GOST 1050.

2.11. Pipe threads must be clean, without flaws or burrs and comply with GOST 6357, accuracy class B.

Pipes with cylindrical threads are used when assembling with seals.

2.10, 2.11. (Changed edition, Amendment No. 3, 4).

2.12. At the seam, blackness on the threads is allowed if the reduction in the normal height of the thread profile does not exceed 15%, and at the request of the consumer does not exceed 10%.

Threads with torn (for cut) or incomplete (for rolled) threads are allowed on threads, provided that their total length does not exceed 10% of the required thread length, and at the request of the consumer does not exceed 5%.

2.13. On a thread, it is allowed to reduce the useful length of the thread (without run-out) by up to 15% compared to that indicated in Table 4, and at the request of the consumer - up to 10%.

2.12, 2.13. (Changed edition, Amendment No. 2, 3, 5).

2.14. Threading on galvanized pipes is carried out after galvanizing.

2.15. (Deleted, Amendment No. 3).

2.16. At the request of the consumer, pipe welds are subjected to testing using non-destructive methods.

(Changed edition, Amendment No. 5).

3. ACCEPTANCE RULES

3.1. Pipes are accepted in batches. The batch must consist of pipes of the same size, the same grade of steel and be accompanied by one quality document in accordance with GOST 10692 with the addition for pipes intended for the manufacture of parts for water supply and gas structures, made of steel in accordance with GOST 1050; chemical composition and mechanical properties of steel - in accordance with the document on the quality of the enterprise - the manufacturer of the workpiece.

Batch weight - no more than 60 tons.

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

3.2. Each pipe in the batch is subjected to inspection of the surface, dimensions and curvature.

Allowed to use statistical methods control according to GOST 18242 * with a normal level. Control plans are established by agreement between the manufacturer and the consumer.
________________
* In the territory Russian Federation GOST R 50779.71-99 is valid.

The outer diameter of the pipes is checked at a distance of at least 15 mm from the end of the pipe.

(Changed edition, Amendment No. 3, 4, 5).

3.3. To control the parameters of the thread, to test for expansion, flattening, bending, the height of the internal burr, the remains of burrs, the right angle and the chamfer angle (for pipes with beveled edges), mechanical properties, no more than 1%, but not less than two pipes from the batch are selected, and for pipes manufactured by continuous furnace welding - two pipes per batch.

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

3.4. All pipes are subject to weight control.

3.5. Each pipe is subjected to hydraulic pressure testing. With 100% quality control of the weld using non-destructive methods, hydraulic pressure testing may not be carried out. At the same time, the ability of the pipes to withstand the test hydraulic pressure is guaranteed.

(Changed edition, Amendment No. 6).

3.6. To check the thickness of the zinc coating on the outer surface and in accessible places on the inner surface, two pipes from the batch are selected.

(Changed edition, Amendment No. 2).

3.7. If unsatisfactory test results are obtained for at least one of the indicators, repeated tests are carried out on a double sample.

The results of repeated tests apply to the entire batch.

4. TEST METHODS

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

The tensile test is carried out according to GOST 10006. Instead of tensile testing, it is allowed to control mechanical properties using non-destructive methods.

(Changed edition, Amendment No. 3, 6).

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

4.3. Hydraulic testing is carried out in accordance with GOST 3845 with exposure to test pressure for at least 5 s.

4.4. The bend test is carried out according to GOST 3728. Galvanized pipes are tested before coating.

(Changed edition, Amendment No. 3).

4.4a. The expansion test is carried out according to GOST 8694 on a conical mandrel with a cone angle of 6°.

Testing on a mandrel with a taper angle of 30° is allowed.

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

4.4b. The flattening test is carried out according to GOST 8695.

(Changed edition, Amendment No. 3).

4.4v. Weld inspection is carried out using non-destructive methods in accordance with regulatory documentation.

(Introduced additionally, Amendment No. 3).

4.5. The thickness of the zinc coating on the outer surface and in accessible places on the inner surface is controlled according to GOST 9.301 and GOST 9.302, as well as with devices of the MT-41NTs, MTZON or "Impulse" type according to regulatory documentation.

4.6. The thread is checked using thread ring gauges in accordance with GOST 2533 (third accuracy class).

In this case, the screw-in of the no-go ring gauge onto the thread should be no more than three turns.

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

4.7. The curvature of the pipes is controlled using a straight edge according to
(Introduced additionally, Amendment No. 4).

5. LABELING, PACKAGING, TRANSPORTATION AND STORAGE

5.1. Labeling, packaging, transportation and storage are carried out in accordance with GOST 10692 with addition.

5.1.1. Pipe threads must be protected from mechanical damage and corrosion with lubricant according to regulatory documentation.

Section 5. (Changed edition, Amendment No. 3).

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

According to their shape, pipes can be not only round, but also oval, rectangular, and square. Despite such diversity in cross-sectional shape, all pipes have mainly two types of parameters: technical and geometric. The geometric dimensions of pipes are represented by such characteristics as outer diameter, wall thickness or the ratio of outer and inner diameters, and length. , that is, pipe sizes are standardized state standards(GOST). Various GOST standards are developed for pipes not only with different ways manufacturing, but also for different materials, used in the production of pipes. On Russian market It is generally customary to indicate pipe sizes in mm (millimeters), but you can also find pipe sizes in inches. The latter are most often indicated for imported pipes. The length of rolled pipe is usually measured in meters.

The most common and popular are the following pipe sizes (diameter from largest to smallest): 1420, 1220, 1020, 920, 820, 720, 530, 426, 377, 325, 273, 219, 159. This rolled product applies to large and medium pipes diameter Smaller diameters They are in much less demand on the market, so, of course, you can find them, but you have to try. On the manufacturer’s website there will definitely be a table of pipe sizes that the company produces. Typically, any manufacturer tries to cover as wide a range of pipe sizes as possible, since in our time the demand market for this type of rolled product is very wide.

Until recently, Russian production has not produced seamless pipes with a diameter of more than 426 mm. But electric welded ones cover almost the entire range. Spiral-welded pipes can have a diameter greater than 1420, but less than 159 - they are not produced. With straight-seam pipes things are different. According to GOST, the smallest diameter of a straight-seam pipe is 8 mm, and the largest is 1420 mm. This is due to the fact that spiral-seam and straight-seam pipes different way manufacturing, although both of them refer to welded pipes.

Pipe sizes are not limited to one diameter. Wall thickness is also one of the important technical indicators. Moreover, the diameter directly affects the size of the pipes, such as wall thickness. The larger diameter allows pipes to be manufactured with a wider range of wall thicknesses. For example, if the dimensions metal pipes straight-seam (or rather, their diameter) is 530 cm, then the wall thickness can vary from 5 to 24 mm. The outer transverse dimensions of longitudinal steel pipes of 1020 mm make it possible to manufacture them with wall thicknesses from 8 mm to 32 mm. The most popular for pipes, for example, with a diameter of 530 mm, are wall thicknesses such as 7, 8, 9 and 10 mm. For a pipe with a diameter of 1020 mm, the most common thicknesses are 10, 11, 12, and 14 mm.

It is interesting that GOST allows manufacturers to violate pipe dimensions within certain limits. In particular, for a straight-seam pipe with a diameter of 1020 mm, the deviation in wall thickness can reach almost 1 mm. More precisely - 0.8 mm, both in the direction of greater and lesser thickness. And since the range of pipes is determined in increments of 1 mm in thickness, this value is quite significant. For example, when buying a pipe with a thickness of 11 mm, do not be surprised that when measured directly it turns out to be a pipe with walls of 10 or 12 mm. This aspect is very great importance when purchasing pipes, since the weight of the rolled product depends on the size of the pipes and the wall thickness. More weight - more price. Why is it customary to indicate weight and not footage? Because the cost of a pipe mainly depends on the raw materials (the so-called price-forming raw material component).

Of course, weighing a pipe is too troublesome. Therefore, when calculating the price, the theoretical weight is taken into account, which is calculated using the formula: weight of 1 linear meter = 0.02466 * wall thickness * (diameter - wall thickness). The wall thickness is taken in millimeters. In practice, the calculation is made in the following way: The buyer measures the thickness of the pipes with a micrometer in order to check the deviation from the permissible values. When loading, use a tape measure to measure the longitudinal dimensions of the pipes (i.e. length) and then, calculating the theoretical weight of 1 linear meter. multiply it by the total length of the pipes.

In relation to these sizes of steel pipes, as well as to the sizes of pipes made of any other material, the GOST requirements are quite loyal. For example: “pipes with a diameter of over 152 mm are manufactured with a length of at least 5 m.” Therefore, despite the fact that used pipes are cut a little before sale, it is impossible to distinguish them by length from new ones. It is worth remembering that when selling straight or spiral-welded pipes, many do not indicate the length. This means that the length of the pipes complies with GOST standards (usually approximately 11 meters). If the price list (advertisement) indicates that the pipes are sold cut at the seams, then their lengths are also within the limits allowed by GOSTs. Seamless pipes are allowed to be manufactured in unmeasured lengths - from 4 meters to 12.5. Therefore, when purchasing pipes, take an interest in GOST standards.

Steel pipe diameters

The diameter of the steel pipe is determined by outer diameter for electric-welded and seamless pipes, and for VGP - according to the nominal diameter (often designated as DN). That is, internal diameter of pipes- Dу, outer diameter of pipes Dн, thread diameter - G. Pipe sizes are specified in millimeters, but VGP pipes are often designated in inches (").

VGP pipe size (GOST 3262-75)

Main pipe dimensions: 15 mm (1/2" inch); 20 mm (3/4"); 25 mm (1"); 32 mm (1 1/4" inches and a quarter); 40 mm (1 1/2"); 50 mm (2"). There are also the following DNs: 10 mm, 65 mm, 80 mm, 90 mm, 100 mm and even 125 mm - but they are rarely used and, as a rule, are replaced by other types of steel pipes (for example, electric welded). Most often, 3/4" pipes are used for risers; 1/2" internal wiring is used.

E/s straight-seam pipes come in the following outer diameters (in millimeters): 10; 12; 13; 14; 16; 17; 17.5; 18; 19; 20; 21.3; 22; 24; 25; 26; 28; thirty; 32; 33; 33.7; 36; 38; 40; 42; 43; 45; 48; 51. For diameters up to 57 mm, it is used VGP pipe appropriate size. The most popular are straight-seam pipes in accordance with GOST 10704-91 with sizes of 57 mm and above. Their main diameters: 57; 60; 63.5; 76; 89; 102; 108; 114; 127; 133; 140; 146; 159; 168; 178; 193; 219; 245; 273; 325; 377; 426; 530.

They start with a diameter of 159 mm and up to 530 mm come with the same dimensions as pipes according to GOST 10704-91. Basic larger diameters (in millimeters): 630, 720, 820, 1020,1220, 1420.

Commonly used diameters of seamless hot-formed pipes (mm): 32; 38; 42; 45; 51; 54; 57; 60; 63,5; 68; 70; 73; 76; 83; 89; 95; 102; 108; 114; 121; 127; 133; 140; 146; 152; 159; 168; 180; 194; 203; 219; 245; 273; 325; 351; 426.

Manufacturers can produce any pipe sizes according to customer requirements.

Pipe internal diameters

According to the standard series adopted in most countries, pipes have the following internal diameters, measured in mm: 6, 10, 15, 20, 25, 32, 40, 50, 65, 80, 100, 125, 200, etc.

A system of measuring thread diameter in inches is also used. 1" = 25.4 mm.

The table shows pipe sizes(diameters) in mm and inches:

When installing a system of steel pipes for residential buildings, pipes with an internal diameter size of Dу = 15, 20 and 32 mm are usually used.

Cast iron non-pressure pipes with diameter Dу = 50 and 100 mm are the most commonly used.

Currently, pipes from polymer materials, which are replacing cast iron and steel.

It should be noted that depending on the type of material used in the manufacture of pipes, different systems designations. In most cases, steel and cast iron pipes designated by nominal bore or internal diameter. Copper pipes, some types of steel pipes, and pipes made of polymer materials are designated by their outer diameter. Therefore, you should be careful when choosing required pipe, and also take into account the wall thickness.

Pipe outer diameters and pipe wall thickness