To date diameter tables steel pipes are relevant for the reason that in almost all areas of construction pipes made of different types of plastic and metal are used. In order to easily understand this variety of materials and learn how to combine them, regulatory documents have been developed, such as tables of steel pipe diameters and their correspondence to 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.

Outside diameter(Dh), pipes, in mm according to GOST and DIN / EN
Conditional (Dy) pipes,	pipe thread (G),in inches	Pipe outer diameter D, mm
			Steel pipes water and gas pipelines	Steel electric welded and seamless	Polymer PE, PP, PVC

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 up only. The value is determined nominal diameter steel pipes according to 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
• Steel pipes seamless 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 the construction of water supply 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 by the following formula: Din = Dn - 2S.

inches	mm.	inches	mm.	inches	mm.	inches	mm.	inches	mm.
-	-	1	25,4	2	50,8	3	76,2	4	101,6
1/8	3,2	1 1/8	28,6	2 1/8	54,0	3 1/8	79,4	4 1/8	104,8
1/4	6,4	1 1/4	31,8	2 1/4	57,2	3 1/4	82,6	4 1/4	108,8
3/8	9,5	1 3/8	34,9	2 3/8	60,3	3 3/8	85,7	4 3/8	111,1
1/2	12,7	1 1/2	38,1	2 1/2	63,5	3 1/2	88,9	4 1/2	114,3
5/8	15,9	1 5/8	41,3	2 5/8	66,7	3 5/8	92,1	4 5/8	117,5
3/4	19,0	1 3/4	44,4	2 3/4	69,8	3 3/4	95,2	4 3/4	120,6
7/8	22,2	1 7/8	47,6	2 7/8	73,0	3 7/8	98,4	4 7/8	123,8

Inch thread parameters

Outer diameter of the connected pipe		SAE Thread Rating	UNF thread rating	Outer thread diameter, mm	Average thread diameter, mm	Thread pitch
mm	inch					mm	threads/inch
6	1/4""""	1/4""""	7/16""""-20	11,079	9,738	1,27	20
8	5/16""""	5/16""""	5/8""""-18	15,839	14,348	1,411	18
10	3/8""""	3/8""""	5/8""""-18	15,839	14,348	1,411	18
12	1/2""""	1/2""""	3/4""""-16	19,012	17,33	1,588	16
16	5/8""""	5/8""""	7/8""""-14	22,184	20,262	1,814	14
18	3/4""""	3/4""""	1""""-14	25,357	23,437	1,814	14
18	3/4""""	---	1""""1/16-14	26,947	25,024	1,814	14
20	7/8""""	---	1""""1/8-12	28,529	26,284	2,117	12
22	7/8""""	7/8""""	1""""1/4-12	31,704	29,459	2,117	12
22	7/8""""	---	1""""3/8-12	34,877	32,634	2,117	12
25	1""""	1""""	1""""1/2-12	38,052	35,809	2,117	12

Copper conductors, wires and cables

Conductor cross-section, mm	Copper conductors, wires and cables
	Voltage, 220 V		Voltage, 380 V
	current, A	power, kWt	current, A	power, kWt
1,5	19	4,1	16	10,5
2,5	27	5,9	25	16,5
4	38	8,3	30	19,8
6	46	10,1	40	26,4
10	70	15,4	50	33,0
16	85	18,7	75	49,5
25	115	25,3	90	59,4
35	135	29,7	115	75,9
50	175	38,5	145	95,7
70	215	47,3	180	118,8
95	260	57,2	220	145,2
120	300	66,0	260	171,6

Aluminum conductors, wires and cables

Cross-section of current-carrying conductor, mm	Aluminum conductors, wires and cables
	Voltage, 220 V		Voltage, 380 V
	current, A	power, kWt	current, A	power, kWt
2,5	20	4,4	19	12,5
4	28	6,1	29	15,1
6	36	7,9	30	19,8
10	50	11,0	39	25,7
16	60	13,2	55	36,3
25	85	18,7	70	46,2
35	100	22,0	85	56,1
50	135	29,7	110	72,6
70	165	36,3	140	92,4
95	200	44,0	170	112,2
120	230	50,6	200	132,0

Inch thread sizes

	Thread diameter in mm			Thread pitch in mm	Number of threads per 1"
	outer d	average d	internal d
3/16	4,762	4,085	3,408	1,058	24
1/4	6,350	5,537	4,724	1,270	20
5/16	7,938	7,034	6,131	1,411	18
3/8	9,525	8,509	7,492	1,588	16
1/2	12,700	11,345	9,989	2,117	12
5,8	15,875	14,397	12,918	2,309	11
3/4	19,05	17,424	15,798	2,540	10
7/8	22,225	20,418	18,611	2,822	9
1	25,400	23,367	21,334	3,175	8
1 1/8	28,575	26,252	23,929	3,629	7
1 1/4	31,750	29,427	27,104	3,629	7
1 1/2	38,100	35,39	32,679	4,233	6
1 3/4	44,450	41,198	37,945	5,080	5
2	50,800	47,186	43,572	5,644	4 1/2

Nominal thread diameter in inches
	Thread diameter in mm			Thread pitch in mm	Number of threads per 1"
	outer d	average d	internal d
1/8	9,729	9,148	8,567	0,907	28
1/4	13,158	12,302	11,446	1,337	19
3/8	16,663	15,807	14,951	1,337	19
1/2	20,956	19,794	18,632	1,814	14
5/8	22,912	21,750	20,588	1,814	14
3/4	26,442	25,281	24,119	1,814	14
7/8	30,202	29,040	27,878	1,814	14
1	33,250	31,771	30.293	2,309	11
1 1/8	37,898	36,420	34,941	2,309	11
1 1/4	41,912	40,433	38,954	2,309	11
1 3/8	44,325	32,846	41,367	2,309	11
1 1/2	47,805	46,326	44,847	2,309	11
1 3/4	53,748	52,270	50,791	2,309	11
2	59,616	58,137	56,659	2,309	11

Unit conversion table

Conversion of energy units	Conversion of pressure units
1 J = 0.24 cal	1 Pa = 1 N/m*m
1 kJ = 0.28 Wh	1 Pa = 0.102 kgf/m*m
1 W = 1 J/s	1 atm =0.101 mPa =1.013 bar
1 cal = 4.2 J	1 bar = 100 kPa = 0.987 atm
1 kcal/h = 1.163 W	1 PSI = 0.06895 bar = 0.06805 atm

Conversion tables for inch to metric sizes. Thread size: table of metric and inch threads

The process of selecting the required cross-sectional sizes of threads, cables and pipes often takes a lot of time. In addition to the fact that it is necessary to select the appropriate dimensions, taking into account the parameters of the equipment, the customer has to independently convert the data into suitable units of measurement. This process requires significant time.

We simplify this task because we invite you to use ready-made translation tables. On the page of our website you will find tables that will help you easily select the necessary threads for inch pipes, copper and aluminum wires and cables. Also, you can use the translation table inch sizes in metric, thereby accurately calculating required dimensions sections.

Unfortunately, most equipment manufacturers leave the customer alone with the calculations. Therefore, a person has to independently search the Internet for translation tables in order to select optimal sizes wire sections and pipe diameters.

We value the time of our clients, providing everyone with the opportunity to use ready-made solutions. Translated in our tables standard sizes from inches to millimeters.

On this page you will also find translations of basic energy units and pressure units, therefore, you will be able to choose the right refrigeration equipment, taking into account the individual placement conditions and operating modes of the units.

On construction market 2 sizes of designs are popular:

• 1\2 and 3\4 - form a separate category. due to special thread parameters (1.814), per 1 unit. measures account for 14 threads;
• within 1 - 6 inches, the pitch is reduced to 2.309, forming 11 threads, which does not affect the reduction or improvement of 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 - ½ inch products, where the outer section is 21.25 mm. This parameter is used when calculating the dimensions of pipes with cylindrical threads. When making calculations for pipes with a cross section of 5 inches, inner size will be 12.7 cm, and the external one will be 166.245 (reduction to 1 decimal place is allowed).

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 between an angle of 55 for inch and 60 for metric designs, and the rounding of the threads is immediately visible, making it impossible for an error to occur. To measure the thread pitch, a thread gauge is used, but instead of it, a regular ruler or other device can be used well.

Replacing steel pipes with polymer ones

In the gas and water supply networks, 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 a 1" pipe, 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, no difficulties arise. But when installing products made of PP, copper or stainless steel instead of steel structures, it is necessary to take into account the difference in name and parameters.

To create a given flow level, the internal diameter of the pipes is taken into account. For ordinary inch pipes it is 27.1 mm, for reinforced pipes it is 25.5 mm, closest to 1". Pipelines are designated in conventional units of the flow area Du (DN). It determines the parameters of the lumen of pipes and is designated in digital values. The pitch of the nominal flow section is selected taking into account the increase in flow characteristics by 40-60% with an increase in the index. If the external cross-section and purpose of the structures are known, using a size table, 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 discrepancies result from the use of copper, aluminum or stainless steel products manufactured according 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 of the Russian Federation and European standards, the following table is used:

How to decide on the diameter?

From diameter water pipes their throughput characteristics depend - the volume of water passed per 1 unit. time. It depends on the speed of water flow. As it increases, the risk of pressure drop in the line increases. Flow characteristics are calculated using formulas, but when planning intra-apartment wiring, they take pipes of certain parameters.

For the plumbing system:

• 1.5 cm (1/2 inch)
• 1 cm (3/8 inch).

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

• 2.5 cm (1 inch);
• 2 cm (3/4 inch).

Considering that the internal cross-section of half-inch polymer pipes varies in the range from 11 to 13 mm, and one-inch ones - 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 pressure, it is necessary to provide for the possibility of routing pipes with a large cross-section. As the diameter increases, the pressure level increases.

Below is a table for determining the permeability 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 values, in inches.
• Nominal parameter (Dn Dn,).
• External size.

  The metric calculation system allows you to classify structures into small - 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 inches - 2.22 cm;
• 1 inch – 2.54 cm;
• 1.5 inches - 3.81 cm;
• 2 inches - 5.08 cm.

To determine the thread diameter, the following indicators are used:

• 1/2 inch pipeline – 2.04 - 2.07 cm;
• 3/4 inches – 2.59 - 2.62 cm;
• 7/8 inches – 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:

PP pipe diameter

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

• Small – 0.5; 1; 1.5; 2; 2.5; 3.2; 4; 5; 6.3 and 7.5 cm are used for heating systems, drainage and water supply in private buildings. An internal cross section of 3.2 cm is most popular in multi-story buildings.
• Average – 8; 9; 10; eleven; 12.5; 16; 20; 25 and 31.5 cm are used for arranging water supply and sewer systems, allowing you to change cast iron products with similar external parameters. The internal sizes of 8, 9 and 10 cm are ideal for chemical media.
• 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, affecting the conditional passability 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 you to reduce the cost of purchasing material and water consumption.

Cost of PP pipes:

Video

It will not be possible to assemble any communication system without making connections, at least because, in the end, you will need to connect to it plumbing equipment. The main thing is that the assembly is of high quality, and the diameters of all connections exactly match each other. Below we will talk a little about the inch pipe.

Differences in pipe sizes

Whether pipes are made of plastic, metal or ceramics, they have a list of characteristics that the buyer uses when choosing them.

The main indicators include the following:

• external section - if the pipe is round;
• internal section - considered to be the working diameter;
• wall thickness - usually characterizes the strength of the pipe.

The external section is formed from the internal section and the wall thickness multiplied by two. Often pipes are connected using a threaded method. The thread is applied to the outer part of the pipe, after which its diameter cannot be considered equal to the outer diameter of the pipe. And due to the fact that during installation it is necessary to start from the thread cross-section, this value becomes more important, and is usually taken into account instead of the actual pipe size.

For example, inch pipes in mm will not equal 25.4, because in this case 1 inch indicates the thread size. Everything becomes more complicated due to the existence of two measurement systems, and due to the presence of many similar products on the market.

Conditional pipe capacity

This parameter is called conditional passage and is denoted by the symbols Dn. There is no specific unit of measurement, so there is only a conditional, non-factual parameter, which in integer expression determines the approximate clearance of the pipe. The gaps between the values ​​are calculated theoretically, so that with the subsequent value the pipe capacity increases by 40-60%.

Efficiency finished system will only be visible in practice. To get a properly functioning plumbing system, you just need to use a table that shows a list of water pipes with the appropriate fitting sizes to match the nominal diameters.

It is easy to conclude that in an inch pipe the diameter of the inner part will be 25.5 mm, while the outer section will be 33.25 mm.

Methods for measuring pipe cross-sections

There are two pipe measuring systems:

• Imperial. The unit of calculation is inches. Used to designate only water and gas pipes and associated plumbing fittings.
• Metric. Calculated in millimeters, centimeters and meters. Used for pipes used for other purposes.

Differences between metric and inch pipes

You can find both steel inch and standard pipes on sale, which can also cause confusion. They clearly differ in the shape of the thread - in an inch pipe the threads are rounded.

Thread pitch can be measured different ways. For inch pipes, measurements are taken along the inner boundaries of the threads, and for metric pipes, along the outer boundaries.

U different diameters the pipes will have different distances:

• for a half-inch pipe and a three-quarter pipe, the pitch will be 1.81 mm;
• 1-6 inches – 2.31 mm.

Converting inch to metric sections

The corresponding tables can be found in reference books. The same GOST, which defines the parameters of the VGP, contains indicators of conditional throughput in millimeters and inches. However, to create a functioning system, indicators of the actual internal cross-section are needed. In this case, as a rule, only external sections can be found in the tables.

Ideally, the table will include the nominal capacity values ​​in inches, the external cross-section of the pipe and the corresponding cross-section in millimeters.

For example, a one-inch steel pipe can be connected to a plastic one, the nominal throughput of which is 25 mm.

Related articles:

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 regulatory documents– standard sizes and requirements for products are regulated by GOST. Each type of pipe has its own standard.

What pipe diameters are there?

Theoretically, the diameter of the pipe is quite simply added to the formulas when determining any values. In practice, everything is more complicated - there are external, internal, nominal diameters, and wall thickness. What concepts are found and what do they mean:

1. Conditional bore is the internal size of the pipe, determined in millimeters. Inches require rounding of values. Is used for correct docking two products, for example, a pipeline and a fitting.
2. Pipe wall thickness (S)– physical quantity in millimeters, on which many quality indicators of the product depend, including cross-country ability and volume. Defined as the difference between the outer and inner diameter.
3. Inner diameter is a physical quantity in millimeters, important parameter to determine the passability of the highway. Formula for calculation: Dvn=Dn-2S
4. Outer diameter (Dn) – has small dimensions (5...102 mm), medium – 103...426 mm, large – 427 mm and more.
5. nominal diameter - close by definition to the nominal diameter, but has more accurate values.

Numerical value of steel pipe diameters

A huge range of steel pipes for various purposes, designs, and types is presented in the form of tables, where the main parameters are:

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

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

Table values ​​of steel pipe diameters

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

Table 1. Standard sizes of welded and seamless steel pipes

Nominal pipe bore (Dy) mm	Thread diameter (G), inch	Pipe outer diameter (Dout), mm
		Steel water and gas pipe	Seamless steel	Polymer
10	3/8"	17	16	16
15	1/2"	21,3	20	20
20	3/4"	26,8	26	25
25	1"	33,5	32	32
32	1 1/4"	42,3	42	40
40	1 1/2"	48	45	50
50	2"	60	57	63
65	2 1/2"	75,5	76	75
80	3"	88,5	89	90
90	3 1/2"	101,3	102	110
100	4"	114	108	125
125	5"	140	133	140
150	6"	165	159	160

In Table 1, the parameters of the nominal bore in mm correspond to certain values ​​of the internal diameter in inches. Notice how the outer diameters differ between different types pipes: seamless, electric-welded, metal-plastic. The difference can reach 17 mm.

How to correctly convert inches to millimeters

When converted to millimeters, the inch dimension is rounded up. 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 practical measurements of steel pipes show, their marked diameter in inches does not correspond to the measured data in millimeters. That is, the size indicated is 1” (corresponding to 25.4 mm), but in reality it turns out to be 33.5 mm. What is the reason for this discrepancy?

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

To correctly select gas and water supply elements with inch markings, the best option There will be a use of tables. When connecting water and gas pipeline elements with metric and inch measurement systems (for example, steel pipelines with products made of copper, brass, polypropylene) it is important to take into account not only the internal, but also the external diameter.

Standard sizes of steel pipes

Generally accepted standard values The internal diameter of steel pipes is determined by the following: 6, 10, 15, 20, 25, 32, 40, 50, 65, 80, 100, 110, etc. The nominal diameter of the pipe, calculated in inches, when converted to metric system it is just rounded up to the nearest parameter from the standard series.

The most commonly used pipes are with diameters from 426 to 1220 mm. These are highways for water, gas, sewer, and irrigation systems.

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

Yulia Petrichenko, expert

Using the tables, the diameters of pipes made of plastic, copper, and brass are determined in the same way. The method of converting inch dimensions to metric is used when connecting products from different materials. If fittings are available, the installation of gas and water mains made of steel is simplified - these nuances are already taken into account in the connecting elements.

How do you cope with calculating pipe diameters? What indicator is most important for you when installing pipelines? Share in the comments.