4 inch pipe. Standard diameters of steel pipes

Pipe diameter in inches and millimeters is very important indicators. Many have faced the challenge of replacing or installing piping and finding the right materials for the job.

It is difficult to understand the huge number of offers on the construction market, therefore, before buying, you should study in detail what the volume of pipe rolling is and how it is used in practice.

The first table of diameters ( its symbolic designation is Ø, further it will be denoted in the article) of pipes shows values in millimeters, while inches are used in the second table ( international designation - inch or in, will be further indicated in the article). An inexperienced master may ask why? And what designations are considered correct?

The reason is that the metric system is used all over the world. This system is based on two indicators: conditional and nominal volume. These concepts are approached in different ways, but in the end they show the external volume. In essence, these quantities are dimensionless, but sometimes they are indicated in millimeters.

Analyzing tabular data, it is possible to compare products of domestic manufacturers and analogues of foreign production.

Interesting! Differing measurements appeared simultaneously with the input copper systems in Europe in the second half of the 20th century. In Russia, at that time, the standards for the metal assortment were determined in mm, and not in inch, this measurement system is widely used today.

Correspondence of two notation systems

In water and gas systems steel pipes are widely used. Their dimensions are shown in whole values or their fractions. For example, a 1" tubular diameter in mm would be 33.5, and a 2" tubular diameter in mm would be 67.

This of course does not correspond to the declared 25.4 and 50 mm. When laying fittings with inch designations for 1 and 2 inch products, there are no difficulties, but replacing with plastic and copper products requires taking into account the discrepancy in the designations.

Why is everything so complicated? The fact is that for the formation of a fluid flow, it is important to take into account inner size. For these reasons, they began to indicate exactly this indicator of 1-inch, 2-inch and all about steel pipes rolling materials. The most accurate indicators are considered in terms of conditional passage.

The nominal bore of 1-inch, 2-inch and the rest of the pipe range is equal to the dimensions of the clearance. To indicate the metric size of 1 inch, 2 inch and any other pipeline, it is recommended to use tables.

Precise definitions - formula for calculation

This knowledge is needed to calculate the amount of transported medium. This is very important for heating systems. For example, when it is necessary to lay a heating system, it is necessary to determine and calculate the size of the assortment in the section so that all housing is heated evenly.

How to accurately determine the cross section of each pipe in quantities such as inches can be suggested by the formula: D \u003d sqrt ((314 ∙ Q) / (V ∙ DT)).

D is the internal volume of the pipe;
Q is the heat flux, which is determined in kW;
V denotes the speed of the heat carrier, it is determined in m / s;
DT is the difference in temperature indicators at the inlet and outlet of the network;
sqrt is the square root.

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Despite the presence of formulas, tables help to quickly determine Ø. This way they win a large number of time.

What is inch volume

Deciphering the diameter of the pipes provided in inches is simple. They are often measured in these quantities. Such one unit is equal to 3.35 cm. It has already been indicated that the interpretation of this value has discrepancies, and this is due to the fact that the assortment is measured not by the external volume, but by the internal one. So, for example, the internal dimension of an inch pipe billet can be different: from 2.55 to 2.71 cm. This value varies depending on the wall thickness.

A 1 inch pipe has an outer diameter of 25.4 mm, a 2 inch pipe is 50 millimeters in metric measurement. Where in technical parameters cylindrical pipe threads take the numbers 33.249 and 66.498?

This thread on 1 and 2 inch products is performed on the outer volume. Therefore, the ratio of the thread diameter to the internal volume is conditional. Based on this, the dimensions of 1 and 2 inch tubing are calculated by adding the value of 25, 4 or 50 with two wall thicknesses of the tubular product.

Before deciphering, you need to take into account that measurements of the product must be performed not from the outside, but from the inside. Why is this needed? The fact is that fastening sections of the highway from different materials, and by taking measurements only from the outside, you can get an incorrect result, which will lead to an error, since the entire assortment differs in wall dimensions.

Also, when deciphering, we must not forget that the standards of different manufacturers are different, they all focus on their own indicators.

If it is difficult to perform such decryption on your own, then you should seek help from professionals. They will effective help when choosing the right products.

Correspondence of metric and inch parameters

All tubular products are manufactured according to a certain standard, and the pressure indicator is a fixed value. Therefore, you need to know exactly the correspondence of the Ø of all pipes shown in inches and mm. Ignoring this correspondence, it is impossible to choose the right pipe assortment.

Watch the video

When selecting a certain size, they are guided by tabular information, and when replacing a guide, we serve as the most approximate parameter. There is no exact correspondence in two different systems of measurement, therefore pipeline elements are often equated in practice.

How this correspondence is applied in everyday life can be found in the table below:

Using this information, you can accurately determine the correspondence of two types of measurements of dimensions, and take parts for work that exactly match each other.

Inch size expression

These indicators are written as an integer, a double stroke is placed next to it, for example, 3 ". Also, the dimensions of the pipe diameter, transmitted in inches, are prescribed in fractions, for example, ½.

Considering these dimensions concrete examples Du correspondences, they will look like this:

The diameter of a standard 12 inch pipe is 300.
3 inch tubular diameter is 80.
8 inch diameter of standard pipe is equal to 200.
The diameter of a standard pipe, at 32, when translated into inches, is shown as 1 ¼
Pipe diameter 40 mm in inch prescribe 1 ½
Ø standard pipe at 15 inches is expressed as a number ½
The Ø of a standard product per 4 inches in terms of metric is 100.
Ø 3/4 inch pipe in metric conversion is 20.
The Ø of a standard 1/2 inch pipe in metric translation shows the number 15.

Watch the video

Pipe diameter in inches and millimeters is used all the time. Knowing these dimensions, you can avoid great difficulties when connecting pipeline elements. And special tables help to find the necessary dimensions of the docking parts and correctly fit them.

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How to determine pipe size in inches: 15 curious facts

In this article, I'm going to talk about the relationship between pipe sizes in inches and millimeters. In addition, the reader and I will have a short digression into the history of length measures and into the current regulatory documentation. So, on your way.

History of the inch

The origin of the word "inch" is derived from the Dutch duim, which literally means "thumb". However, another word is used as an international designation for this measure of length - inch;
Like all old measures of length, the inch originates in human anthropometry and is equal to the length of the extreme phalanx at thumb. In addition, it is equal to 1/12 of a foot (from English foot - foot) and 1/36 of a yard (according to legend, a yard was equal to the distance from the nose to the end of the thumb of the outstretched hand of King Henry the First of Britain);

It is believed that Henry's sword was one yard long.

AT different countries and at different times took an inch different meanings. The Vienna inch (Austria-Hungary) is 2.63 cm, the French inch is 2.707, the Old Polish inch is 2.48, the New Polish inch is 2.4, the Prussian sample of 1816 is 3.766 cm at all;
In Russia, this measure of length was introduced by Peter the Great. Prior to that, in trade and in calculations, domestic units of measurement were used, also based on anthropometry - a vershok (the length of the first phalanx of the index finger), a span (it is measured between the large and divorced to the maximum distance). index fingers), arshin (step length of an adult);
Currently, the most common is the English inch. Since 1958, it has been agreed to consider it equal to 2.54 cm.

About the mess

Dear reader, do you think that you can calculate the cross section of a steel pipe or squeegee in inches using a caliper and dividing the result by 25.4? It wasn't there.

Conditional pass

Steel water and gas pipes, the cross section of which is usually indicated in inches, are marked not with a diameter at all, but with a conditional passage. It is close to the internal section, but not necessarily equal to it. It only means that the corresponding pipe thread;

The actual inner diameter is determined by the nominal bore (more precisely, by the outer diameter corresponding to it) and the type of pipe (it can be ordinary, light or reinforced);
The actual internal section of products with the same DN (nominal bore) may differ by 0.3 cm due to the walls;
The internal sectional area and, accordingly, the throughput of a light and reinforced pipe with a nominal size of half an inch differ by 20%. At the same time, more throughput light product, but reinforced due to the greater wall thickness and, accordingly, greater mass running meter higher price.

Samples of pipe products produced in accordance with GOST 3262 - 75.

Standards

With all my immense respect for the Soviet standardization system, it’s impossible to name how, according to the current standards, pipe sizes in inches and centimeters are related, otherwise than as a mess:

The section indicated in the documentation in inches cannot be obtained by simple conversion from mm or other SI units. The conversion factor is different for each diameter and in no case does it correspond to a completely logical value of 25.4;
To determine the number of inches based on the measurement results, you will have to go into the reference or regulatory documentation. However none of the GOSTs contains a table of pipe sizes in inches and millimeters. The actual dimensions for a certain control and type of product can be found in GOST 3262-75, which regulates the production of black steel and galvanized water and gas pipes. Meanwhile, the parameters of the corresponding threads are indicated in another GOST - under the number 6357-81.

The second standard indicates the dimensions of the crests and troughs of the thread in SI units, but designates cylindrical pipe threads in inches.

Easier, even easier

So, in order to correlate the pipe size in inches and mm, you need to overlay regulatory documents and painstakingly compare them. So right?

Dear reader, I will not bore you and just lay out a couple of tables that are compilations of the standards mentioned above.

Here is the correspondence between remote control and the treasured British inches:

DU	inches
15	1/2
20	3/4
25	1
32	1 1/4
40	1 1/2
50	2
65	2 1/2
80	3
90	3 1/2
100	4
125	5
150	6

In addition to those indicated, GOST 3262-75 provides for conditional passages 6, 8 and 10. However, they are not used in plumbing, and threaded fittings cannot be found for them.

The minimum cross section used in plumbing is DN 15.

But the ratio of remote control and actual dimensions:

DU	External diameter	Wall thickness
DU	External diameter	reinforced	ordinary	Light
15	21,3	3,2	2,8	2,5
20	26,8	3,2	2,8	2,5
25	33,5	4	3,2	2,8
32	42,3	4	3,2	2,8
40	48	4	3,5	3
50	60	4,5	3,5	3
65	75,5	4,5	4	3,2
80	88,5	4,5	4	3,5
90	101,3	4,5	4	3,5
100	114	5,0	4,5	4
125	140	5,5	4,5	4
150	165	5,5	4,5	4

How, using these tables, can you calculate the actual dimensions of a 1 inch pipe with your own hands? Very simple:

In our case, one inch corresponds to a nominal diameter of DN 25 and means an outer diameter of 33.5 mm. The inner diameter of a light pipe will be 28.1 mm, an ordinary one - 27.1, and a reinforced one - 25.5 mm.

Polymer and metal-polymer pipes

They are always marked with the outer diameter in millimeters; wall thickness is indicated either in the marking or in the technical documentation. To obtain the same throughput as a known size steel liner, you need to choose a product with the same internal diameter. Let me remind you that it is calculated as the difference between the diameter and twice the wall thickness;

In the photo - metal-plastic water supply. The marking indicates the outer diameter (16 mm) and wall thickness (2 mm).

To simplify my task of selecting the diameter, I usually use polymer and metal polymer products with a cross section one step larger than that of an eyeliner or riser. For example, instead of a water supply line DU 15, metal-plastic with an outer diameter of 20 mm can be mounted, and instead of a 25 mm riser - 32 mm.

Conclusion

I hope that I was able to answer all the questions the reader had. As always, additional thematic information can be explored by watching the video in this article. I would appreciate your comments and additions. Good luck, comrades!

August 1, 2016

If you want to express gratitude, add a clarification or objection, ask the author something - add a comment or say thanks!

The most important parameters of pipe products are pipe diameters in inches and millimeters. Many property owners are faced with the need to replace the piping system and, accordingly, the search for the required materials. High-quality assembly can be ensured provided that the diameter of the pipe and the dimensions of the connecting elements match.

Dimensional designations of modern types of pipes

When choosing the necessary products, regardless of what material they are made of, a number of indicators should be taken into account:

Outer diameter (Dн) in millimeters. The main characteristic of pipes. The sum of the internal section of the pipe and twice the wall thickness is the external parameter.
Inner diameter (working section) in millimeters. This setting has great importance to determine the patency of the system. To find out, it is necessary to subtract twice the size of the pipe wall thickness from the outer diameter.
Wall thickness in millimeters (S). The quality of pipe products - its volume and strength - depends on this parameter. It is calculated as the difference between the values of the outer and inner sections of the pipe.
Nominal passage in millimeters, marked as Dу. Is the average value of the inner diameter, which is rounded up to standard parameter to the big side. This size is taken into account when choosing the appropriate fittings and fittings.
Nominal diameter in inches. This concept was introduced to standardize the labeling of products made from different materials. The value is equal to the nominal bore (read also: “Nominal pipe diameter is what? Norms and standards”). This option allows you to select products made from different kind raw materials, when combining them in the system. The fact is that pipe sizes in inches are indicated on steel pipe products, but copper and aluminum are marked in millimeters. Inch values must be rounded up.

Measuring systems for pipes

There are two methods of measurement, the emergence of which has historical roots:

imperial system- expressed in inches. Currently, it is used exclusively for water and gas pipes made of steel and fittings for arranging water mains;
metric system has the following units of measurement - millimeters, centimeters, meters. It is used for all other types of pipe products.

In the case of joining pipelines made of various materials, and there are difficulties in converting to millimeters and vice versa. An ordinary inch is equal to 25.4 millimeters - it is used to measure the diameter of the inner. But there is also a special unit of measurement - this is a pipe inch, which is 33.249 millimeters. Its peculiarity is explained by the fact that it includes the inner diameter and the thickness of two walls. The exception is the ½ inch conduit.

Differences between metric and inch systems of measurement

Visually, it will not be difficult to distinguish an inch pipe from a metric one. To do this, just look at the threads of the thread. At the same time, it is almost impossible to notice the difference in degrees between the turns with the naked eye, since it is 55 for an inch product, and 60 for a metric product. But it is almost impossible not to see that a one-inch pipe has rounded threads.

To measure the thread pitch, you can use a special device called a thread gauge, but if it is not available, a regular school ruler or any other measuring device will do.

Metric pipes are measured only along the outer boundaries of the threads, and inch pipes are measured exclusively along the inner surface. To find out the pipe size in inches and mm,

one should use the imperial or metric system of measurement, each of which is currently in demand.

Converting inch sizes to metric sizes

If necessary, you can use a special reference literature, containing the corresponding tables. For example, in GOST, which regulates the parameters of the VGP, there are values of both an inch conditional transition and a millimeter one.

So, if you use the table, it becomes clear that the dimensions of the inch pipe will not be equal to 25.4 millimeters. Conditional passage - will be 25 millimeters with an outer diameter of -33.6 millimeters.

The most convenient table contains the size of the conditional passage of the pipe, expressed in inches, its outer dimension and equivalent diameter in millimeters. It corresponds to the inch bandwidth. So a steel pipeline section of 1 inch can be connected to a polyethylene product, in which the conditional passage is 25 millimeters.

What is the size of inch pipes in mm?

On the construction market popular 2 size designs:

1\2 and 3\4 - make up a separate category. due to special thread parameters (1.814), per 1 unit. measures accounted for 14 strands;
within 1 - 6 inches, the pitch is reduced to 2.309, forming 11 threads that do not affect the decrease or increase in the quality of the connection.

One inch is 25.4 mm long, it is used to determine the internal parameters, but when laying reinforced pipes, the diameter is 33.249 mm (including the internal section and 2 walls). In assortment steel structures there is an exception - products in ½ inch, where the outer section is 21.25 mm. This parameter is used when calculating the dimensions of pipes with cylindrical threads. When calculating for pipes with a cross section of 5 inches, the internal dimension will be 12.7 cm, and the external - 166.245 (reduced to 1 decimal place is allowed).

The difference between measurement systems

In terms of external parameters, inch designs do not differ from metric ones, the difference lies in the type of notches. There are 2 types of threads according to the inch system - English and American. The first option corresponds to a notch angle of 55 degrees, and the metric (American) system with an angle of 60 degrees. generally accepted.

At different degrees, it is difficult to distinguish the angle by 55 for inch and 60 for metric designs, and the rounding of the threads is immediately visible, the occurrence of an error is impossible. A thread gauge is used to measure the thread pitch, but an ordinary ruler or other device is well used instead.

Replacing steel pipes with polymer ones

In gas and water supply network steel products are used, the diameter of which is indicated in inches (1″, 2″) or fractions (1/2″, 3/4″). When measuring the cross section of the pipe 1″, the result will be 33.5 mm, which corresponds to 1″ (25.4 mm). When arranging pipeline reinforcing elements, where the parameters are indicated in inches, there are no difficulties. But when installing products made of PP, copper or stainless steel instead of steel structures, it is required to take into account the difference in the name and parameters.

To create a given level of flow, the inner diameter of the pipes is taken into account. For inch ordinary pipes, it is 27.1 mm, for reinforced 25.5 mm, closest to 1 ″. Pipelines are designated in conventional units of the flow area Du (DN). It determines the parameters of the pipe clearance and is indicated in numerical values. The step of the nominal flow section is selected taking into account the increase in throughput characteristics by 40-60% with an increase in the index. If the external transverse section and the purpose of the structures, using the table of dimensions, the internal cross section is determined.

In the process of connecting steel pipes with polymer structures, replacing one with another, conventional adapters are used. Dimensional mismatch results from the use of copper, aluminum or stainless steel products manufactured to metric standards. The actual metric dimensions of the pipes are taken into account - internal and external.

Steel pipes of the Russian Federation in comparison with the European standard

To compare the range of pipes according to GOST RF and European standards, the following table is used:

How to decide on the choice of diameter?

Their throughput characteristics depend on the diameter of water pipes - the volume of water passed for 1 unit. time. It depends on the speed of the water flow. With its increase, the risk of pressure drop in the line increases. Throughput characteristics are calculated according to formulas, but when planning intra-apartment wiring, they take pipes of certain parameters.

For the plumbing system:

For the riser, structures with an internal cross section are used:

Given that the internal cross section of half-inch polymer pipes varies from 11 to 13 mm, and one-inch pipes from 21 to 23, an experienced plumber will be able to determine the exact parameters when replacing. With a complex type of wiring, numerous joints, turns and network laying on long distance, reducing the pressure, it should be possible to carry out the wiring of pipes with a large cross section. As the diameter increases, the pressure level increases.

Below is a table for determining the patency of steel pipes:

Steel pipe diameter

The cross section of the pipes corresponds to a number of indicators:

Nominal diameter (Dn, Dy) - nominal parameters (in mm) of the internal cross-section of pipes or their rounded indicators, in inches.
Rated value (Dn Dn,).
external size. The metric calculation system allows classifying structures into small ones - from 5 ... 102 mm, medium - from 102 ... 426, large - 426 mm and more.
Wall thickness.
inner diameter.

The internal cross section of pipes with different threads corresponds to the following parameters:

1/2 inch pipeline - 1.27 cm;
3/4 inch - 1.9 cm;
7/8 inch - 2.22 cm;
1 inch - 2.54 cm;
1.5 inches - 3.81 cm;
2 inches - 5.08 cm.

The following indicators are used to determine the thread diameter:

1/2 inch pipeline - 2.04 - 2.07 cm;
3/4 inches - 2.59 - 2.62 cm;
7/8 inch - 2.99 - 3 cm;
1 inch - 3.27 - 3.3 cm;
1.5 inches - 4.58 - 4.62 cm;
2 inches - 5.79 - 5.83 cm.

Table of correspondence between the diameter of steel pipes and polymer structures:

Steel pipe prices:

Pipe diameter PP

PP pipes are produced with a diameter of 0.5 to 40 cm or more. The diameter is internal and external. The first indicator allows you to find out the volume of environments traversed in 1 unit. time. The external cross section is used for construction calculations, namely the choice of a niche or pit for laying a highway. External parameters allow you to choose the right fittings with the corresponding internal indicators.

Small - 0.5; one; 1.5; 2; 2.5; 3.2; four; 5; 6.3 and 7.5 cm is used for heating systems, drains and water supply in private buildings. An internal cross section of 3.2 cm is most popular in multi-storey buildings.
Medium - 8; 9; ten; eleven; 12.5; 16; twenty; 25 and 31.5 cm is used for arranging plumbing and sewer systems, allowing you to change cast iron products with similar external parameters. Internal dimensions of 8, 9 and 10 cm are ideal for chemical environments.
Large - 40 cm or more is used for arranging cold water supply and ventilation systems.

Pipes are marked in inches and mm. When choosing designs for plumbing and heating system, the wall thickness is taken into account, which affects the conditional patency of highways with the same external parameters. With an increase in its parameter, an increase in pressure is allowed in plumbing system. Small dimensions allow to reduce the level of costs for the purchase of material and water consumption.

Inch pipe - dimensions in mm and diameter

Inch pipe - dimensions (in mm), specifications and prices. Correspondence table for steel and plastic products for gas and water supply. The difference between GOST and European standards.

Pipe 1 inch - what diameter

It is impossible to mount a communication system of any kind in such a way as to completely avoid connections. If only because the pipeline is eventually brought to some kind of consumption object - plumbing, radiator, washing machine, and connects to the outlet of the device. And the main condition for a tight, high-quality assembly is the correspondence between the diameter of the pipe and the size of the connecting element.

Dimensional parameters of the pipe

Regardless of the material of manufacture - polymer, metal, ceramics, and so on, the product is characterized by a number of indicators, based on which, the consumer can choose the necessary product.

The outside diameter is outer size pipes (we are talking only about a round section).
Internal - the size of the working section.
Wall thickness - largely determines the strength of the product.

The sum of the inner diameter and twice the wall thickness is the outer diameter. The actual state of affairs corresponds to this statement. But when it comes to VGP, it is necessary to take into account the following point. Most often, conduits are connected by a threaded method. The thread is applied to the outer part, as a result, the diameter of the thread is by no means equal to the outer size. And since for installation it is important to know exactly the thread indicators, then given parameter turns out to be more important and is often indicated instead of the actual size of the product.

For example, a 1 inch conduit is not at all equal in outer diameter to 2.54 cm, since 1 inch is an indication of the size of the thread.

This confusion is exacerbated by the use of two measuring systems on the one hand, and the variety of products currently available on the other.

Conditional pass

The task of the plumbing system is to uniformly supply all consumers with the proper amount of water. The main calculation parameters are the throughput of the pipeline, that is, the amount of water that can pass per unit of time.

This parameter is called conditional passage - Dn. It does not have a unit of measurement as such - it is a conditional, non-actual value, indicated in integers and indicates the approximate conditional clearance of the pipe. The step between the values is calculated theoretically, with the condition that with each subsequent increase, the throughput of the pipeline increases by 40–60%.

The convenience of the system is obvious only in practical use. It is enough to select conduits and fittings with an equal conditional passage according to the table in order to guarantee a working plumbing system.

Accordingly, a 1 inch steel pipe has a nominal bore of 1 inch, while its actual inner diameter is 25.5 mm, the outer threaded one is 33, 25.

Measuring systems

The presence of two methods of measurement has historical roots.

Imperial - in inches, today it is used only for water and gas steel pipes and related plumbing fittings.
Metric - in mm, cm and m. Used for any other pipe products.

When joining conduits from different materials, difficulties arise with the recalculation from one system to another.

Inch and metric pipes

Both inch and standard steel conduits are produced, which further confuses the matter. You can visually distinguish them by the type of thread of the thread - a 1-inch pipe has rounded threads. The photos show samples.

Thread pitch is measured in different ways. In metric products, along the outer boundaries of the threads, in inch products, along the inner ones. The distance is different different sizes sections.

Pipe 1 inch, which is used in the imperial system, is not equal to 2.54 cm, as it should be, but equals 3.3249, since it includes both the internal dimension and the wall thickness. The exception is the ½ inch conduit.

Converting inch to metric sizes

The reference literature contains corresponding tables. The same GOST, which regulates the parameters of the VGP, indicates both an inch nominal bore and a millimeter one. Unfortunately, in order to assemble the system into one whole, the actual value of the inner diameter is also required. While the tables more often indicate the outer.

The most convenient table contains the nominal size in inches, the external size of the pipe and the equivalent diameter in mm. It indicates a bandwidth that corresponds to an inch.

For example, a 1 inch steel conduit can be connected to a polyethylene conduit, the conditional passage of which is 25 mm.

Steel pipe diameters

In practice, there are diameters: nominal, internal, external, conditional passage. The values are indicated in the marking of pipes: for steel - in inches, for others - in millimeters. How to determine the diameter of a steel pipe in mm? This will help the tables of correspondence of the diameters of steel products.

Steel pipes with a diameter of 100 mm

The main characteristic of a steel pipe is its diameter. This parameter determines the purpose, length of the pipeline, composition and physical characteristics transported substance. All diameter values are standardized and regulated by regulatory documents - standard sizes and requirements for products are regulated by GOST. Each type of pipe has its own standard.

What pipe diameters exist

Theoretically, the diameter of the pipe is quite simply added to the formulas when determining any values. In practice, everything is more complicated - they distinguish between outer, inner, nominal diameters, wall thickness. What are the terms and what do they mean?

Conditional passage - the internal size of the pipe, determined in millimeters. In inches requires rounding. It is used for the correct joining of two products, for example, a pipeline and a fitting.
Pipe wall thickness (S)– physical quantity in millimeters, on which many quality indicators of the product depend, including throughput, volume. It is defined as the difference between the outer and inner diameters.
Inner diameter - a physical quantity in millimeters, important parameter to determine the patency of the highway. Formula for calculation: Dvn=Dn-2S
Outer diameter (Dn) - has small dimensions (5 ... 102 mm), medium - 103 ... 426 mm, large - 427 mm or more.
nominal diameter - close by definition to the nominal diameter, but has more accurate values.

The numerical value of the diameters of steel pipes

Huge range of steel pipes for various purposes, performance, types are presented in the form of tables, where the main parameters are:

conditional passage (or nominal diameter);
outer diameter of the pipe;
wall thickness.

Sometimes the weight of the product is entered into the steel pipe diameter table depending on its dimensions, as well as the parameters of the nominal diameter.

Tabular values of steel pipe diameters

Tables are convenient to use when determining the exact dimensions of products when they are connected. For example, steel pipes are most often indicated in inches - this dimension is accepted in many parts of the world. While it is customary to calculate polymer products in millimeters, which creates some difficulties when joining metal-plastic, cast iron, copper pipes with steel in the plumbing system. Diameter matching tables help determine the required dimensions of the connecting elements and connect them correctly.

In table 1, nominal diameters in mm correspond to certain values of the inner diameter in inches. Pay attention to how the values of the outer diameter differ for different types of pipes: seamless, electric-welded, metal-plastic. The difference can reach 17 mm.

How to convert inches to millimeters correctly

Inch units are rounded up when converted to millimeters. Obviously, knowing the constant 1 inch is equal to 2.54 cm, you can independently calculate the diameter values according to the metric dimension. But the problem is not how to calculate, but how to correctly determine the diameter. as show practical measurements steel pipes, their marked diameter in inches does not correspond to the measured data in millimeters. That is, the size is 1 ”(respectively 25.4 mm), but in reality it turns out 33.5 mm. What is the reason for this discrepancy?

First of all, the inner diameter of the pipe is stamped in the designation. Secondly, the unit of measurement of the diameter is the dimension of the conditional passage (DN), which is indicated in integers. Moreover, the value of the size increases with the growth of the index (patency) of the pipe by 40-60% with each step. The conditional passage of the pipe corresponds to the internal clearance (nominal diameter) of the line, but an integer is taken as the final value, rounding the calculated one up. The conditional passage of the line is standardized according to GOST 355-52.

To correctly select gas and water elements with inch markings, the best option tables will be used. When connecting elements of a water and gas pipeline with metric and inch systems of measurement (for example, steel pipelines with products made of copper, brass, polypropylene), it is important to consider not only the inner, but also the outer diameter.

Standard sizes of steel pipes

Common standard values the inner diameter of steel pipes are determined next: 6, 10, 15, 20, 25, 32, 40, 50, 65, 80, 100, 110, etc. The conditional passage of the pipe, calculated in inches, when converted to the metric system, is just rounded up to the nearest parameter from the standard range.

The most commonly used pipes are from 426 to 1220 mm in diameter. These are lines for water, gas, sewer, irrigation systems.

For plumbing and heating in apartments of multi-storey and private buildings, pipes of small diameter are used. Medium-diameter steel products are used for risers in urban infrastructure, as well as in the oil industry. These are products with a diameter of ¾", for wiring inside ½".

According to the tables, the diameters of pipes made of plastic, copper, brass are similarly determined. The method of converting inch dimensions to metric is used when connecting products from different materials. In the presence of fittings, the installation of gas pipelines made of steel is simplified - these nuances are already taken into account in the connecting elements.

Diameters of steel pipes: table, dimensions in inches and millimeters, guests

To one degree or another, most people had to deal with the installation of a water supply system, the replacement of its pipes. It is quite difficult for a non-professional to navigate the vast number of offers on the market. Whether you hire a craftsman or prefer to work with plumbing equipment on your own, it is very useful to figure out what the diameter of water supply pipes can be, what are the differences in the characteristics of products made from different materials. And even more so for a professional.

Inch sizes - a bit of history

For intra-house water supply networks, the following types of pipes are most often used:

metal - steel, copper or brass;
plastic;
metal-plastic (combined).

Water pipes made of various materials differ in the classification of measurement measures.

Dimensions water pipe are given the following parameters(see fig.1):

Dn- outer diameter;
Din- internal;
h - wall thickness.

AT former USSR, in the apartments of unprivileged citizens there were only steel pipes, for which an original system for designating their sizes was invented. For example, a half-inch pipe has a half-inch (12.7 mm) inside diameter. Its outer diameter and thread diameter, respectively, are about 21 mm. Therefore, for threading, the word "pipes" is necessarily added. In our example: 1/2" pipes.

Types of pipe diameters for water supply

Compliance with metric and inch sizes

In today's market, the offer is much richer. The choice is especially difficult if you have to join products from different materials. For example, how to compare diameters polypropylene pipes for water supply and steel or brass (see Fig. 2).

The fact is that in the rest of the world the metric system for designating sizes has taken root. Although it has quite a lot of conventions.

It is based on two concepts:

Nominal diameter - D at.
Nominal diameter - D n .

The approach to determining them is somewhat different, but, in the end, both of these quantities determine the outer diameter. In fact, these are dimensionless quantities, although sometimes they are indicated with the dimension of mm.

Comparison of steel pipes of the Russian Federation and the European standard

Any product has GOST - pipes for water supply are no exception. You can compare the range of products produced in the Russian Federation in accordance with GOST and similar products manufactured in accordance with the European standard using the following table:

How to choose diameter

The diameter of the pipes for water supply depends on their throughput - the amount of water flowing through them per unit of time. The throughput depends on how fast the water flows. In turn, this speed is the greater, the greater the pressure drop in the system.

Of course, there are calculation formulas for calculating the throughput, there are tables that allow you to somewhat simplify the calculation. However, the calculation process using these formulas and tables is quite complicated, and therefore, they are practically not used for intra-apartment wiring. They do it easier - pipes of a certain section are usually taken:

for intra-apartment wiring 3/8 or 1/2 inch;
for a riser - 3/4 or 1 inch.

We hope that the data given in the article will not only help you choose a water supply pipe of the required diameter for repair or replacement, but will also allow, if necessary, to properly dock products made using different technologies.

TECHInfo section on the site "Conversion of plumbing inches to millimeters"

It seems that you can simply measure the diameter of the pipe and convert to standard inches (25.4 mm). But the result will be wrong. For example, a pipe with an outer diameter of 26.8 mm, when converted to standard inches, will give 1.06 inches. A person unfamiliar with the intricacies of plumbing art will decide that this is an inch pipe with a slight deviation. But it's actually a 3/4" pipe.

Convert plumbing inches to millimeters

The size of the water and gas pipes It is customary to indicate in inches and fractions of an inch. That's how it happened historically. And for an ignorant person, converting these sizes into metric ones is a fair amount of difficulty. Let's try to figure this out...

The task of converting inch pipe sizes to metric (millimeters) often arises when replacing steel pipes with plastic, metal-plastic or copper pipes. The size of these pipes is indicated in millimeters. Errors in selection are not allowed. If you put a pipe of a smaller diameter, then the water pressure will drop. If more, the extra money will be wasted.

The trick here is that for pipes, the inner diameter is important, which determines the throughput of the pipe. And the inch size determines the parameters of the thread cut on pipes, spurs, couplings, elbows, tees, valves and other fittings. Therefore, to convert inch pipe sizes to metric, you need to use the table.

Equivalent diameter defines the nominal size of the pipe, providing the same throughput as the corresponding inch.