What is the size of inch pipes in mm? Nominal pipe diameter Dy. mm

Pipe diameters in inches and millimeters are very important indicators. Many faced the problem of replacing or installing the pipeline, 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.

You can immediately use the online calculator below for translation without getting acquainted with the theory.

Online calculator to convert inches to millimeters and vice versa

An example of how to enter data into a calculator

When recording the size in inches, separate the integer part of the number from the fractional part (if any) with a space: for example, 10 1/4, or 20 4/8; otherwise you get 101/4 and 204/8. Fractional numbers in millimeters are entered with a period, not a comma (25.4, not 25.4).

Enter the data for the calculation in the next. order: left-click in the corresponding parameter window to display a blinking cursor; enter your numbers. The fractional part of an inch is entered without a sign.

1 inch \u003d 25.4 millimeters (mm). Nowadays, the inch, due to its clarity, is often used to measure the diameters of water-gas pipes and threads. Many parts are also multiples of inches. In addition to whole inches, measurements are taken in fourths (1/4 ″), eighths (1/8 ″), sixteenths (1/16 ″), thirty-second (1/32 ″) of an inch, etc.

If you have any questions about using the online calculator, you can always ask a question in the form of a comment. We also strongly recommend that you read the instructions (located under the calculator).

How to convert inch to metric

Conversion of inches to metric indicators of pipe volumes is carried out, guided by special tables. Here is an example of such a table:

To convert the metric diameter of the pipe assortment, you need to round up in the direction of increase. When making this translation, you need to remember that according to international standards, one inch is taken into account as 2.54 cm.

With such data, the translation can be done using the simplest calculator. Now that the cross-section of the pipe-rolling assortment has been calculated, its volume should be correctly calculated.

In practice, in order to translate the measurements of steel options, you need to take into account that the inch values \u200b\u200bwhen calculating will not equal the indicator in mm. The reason is that when marking is applied, the internal volume is prescribed.

After that, the unit of measurement becomes the conditional passage, indicated by an integer. It is for these reasons that values \u200b\u200bmust be rounded to translate. It is difficult for an inexperienced master to make such a translation.

Therefore, if you need to translate these indicators, it is better to turn to professionals for help, or perform a translation based on a special table. Professionals will help you translate the required values, and help you choose the right products and other parts for the pipeline.

Translation tables

In the construction of highways for various purposes, different pipe-rolling materials are used: steel, copper, brass, plastic and others. All these products are distinguished by their classification and measurement.

The overall dimensions of all pipe products are set by the following indicators:

Дн - external Ø.
Dv - inner Ø.
h - wall thickness.

Previously, only steel lines were used, and they created their own sizing system. ... These are its internal dimensions. That is, this indicator takes into account not only the size of a half-inch pipe billet, but also its throughput capacity.

And the outer girth of a half-inch workpiece is 2.1 cm.Therefore, in the table, near the half-inch thread, the word pipes must be added. Knowing the exact dimensions of half-inch and any other type of assortment, you can quickly make the right choice of the right volumes.

This is clearly seen in the table:

Dimensions (inches)	1/2	3/4	7/8	1	1,5	2
Internal Ø (metric)	12,7	19	22,2	25,4	38,1	50,8
Thread Ø (mm)	20,4-20,7	25,9-26,2	29,9-30,0	32,7 – 33,0	45,8 – 46,2	57,9 – 58,3

Now these dimensions are usually indicated as the following table shows:

The first diameter table ( its symbolic designation is Ø, hereinafter it will be indicated in the article) of pipes shows the values \u200b\u200bin millimeters, and the second table uses inches ( international designation - inch or in, further will be indicated in the article). An inexperienced master may wonder why this is so? 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 result they show the external volume. In essence, these quantities are dimensionless, but sometimes they are indicated in millimeters.

By analyzing the tabular data, one can compare products of domestic manufacturers and analogues of foreign production.

Interesting! The measurement discrepancy emerged simultaneously with the introduction of copper systems in Europe in the second half of the 20th century. In Russia at that time standards for metal gauge were defined in mm, not in inch, this measurement system is widely used today.

Correspondence of two notation systems

Steel pipes are widely used in water and gas systems. Their dimensions are shown in whole values \u200b\u200bor their fractions. For example, a 1-inch tubular in mm would be 33.5, and a 2-inch tubular in mm would be 67.

This certainly does not correspond to the declared 25.4 and 50 mm. When laying fittings with inch designations to products of 1 and 2 inch, there are no difficulties, but replacement 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 the internal size. For these reasons, this indicator began to be indicated for 1-inch, 2-inch and all other tube-rolling materials. The most accurate indicators are considered in terms of the nominal size.

The nominal bore of 1-inch, 2-inch and the rest of the pipe assortment is equal to the dimensions of the lumen. To designate metric sizes of 1 ", 2" and any other pipeline, it is recommended to use tables.

Exact Definitions - Calculation Formula

This knowledge is needed to calculate the amount of the 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 rolled 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 input and output of the network;
sqrt - square root.

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Despite the presence of formulas, tables help to determine Ø faster. A lot of time is gained in this way.

What is inch volume

The decoding of the pipe diameter, 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 decoding 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 tubular 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 has a metric dimension of 50 millimeters. Where do the numbers 33.249 and 66.498 come from in the technical parameters of the cylindrical pipe thread?

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

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

Also, when decoding, we must not forget that the standards of different manufacturers are different, they are all guided by their own indicators.

If it is difficult to perform such a decoding on your own, then you should seek help from professionals. They will provide effective assistance in choosing the right products.

Correspondence between 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-rolling assortment.

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When selecting a certain size, they are guided by tabular information, and when replacing it, we serve as a guideline as close as possible. There is no exact match in two different measurement systems, therefore, pipeline elements are often equated in practice.

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

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

Inch size expression

These indicators are prescribed as a whole number, next to it they put a double prime, for example, 3 “. Also, the dimensions of the diameter of the pipe rolling, transmitted in inches, are prescribed by a fraction, for example, ½.

If we consider these dimensions with specific examples of the Dy correspondences, they will look like this:

The diameter of a standard 12 inch pipe is 300.
3 inch tubing diameter is 80.
An 8-inch diameter of a standard rolled pipe equals 200.
The diameter of a standard pipe roll, at 32, when converted to inches, is shown as 1 ¼
Pipe diameter 40 mm in inch prescribe 1 ½
Ø 15 inch standard pipe expressed as ½
The Ø of a standard product by 4 inches in metric is 100.
Ø 3/4 inch pipe in metric translation is 20.
The Ø of a standard 1/2 '' pipe in metric conversion shows the number 15.

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Pipe diameters in inches and millimeters are used continuously. Knowing these dimensions, you can avoid great difficulties when connecting pipeline elements. And special tables help to find the required dimensions of the docking parts and correctly adjust them.

In the construction market, 2 sizes of structures are popular:

1 \\ 2 and 3 \\ 4 - make up 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 decrease or increase in the quality of the connection.

One inch is 25.4 mm long, it is used to determine internal parameters, but when reinforced pipes are installed, the diameter is 33.249 mm (including internal section and 2 walls). In the range of 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 a cylindrical thread type. When calculating for pipes with a cross section of 5 inches, the inner dimension will be 12.7 cm, and the outer dimension will be 166.245 (abbreviated 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 the angle by 55 - for inch and 60 - for metric designs, and the filaments are immediately visible, an error is impossible. A thread gauge is used to measure the thread pitch, but a regular ruler or other device is well used instead.

Replacement of steel pipes with polymer

In the 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 a pipe cross-section of 1 ", the result is 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 PP, copper or stainless steel products instead of steel structures, it is necessary to take into account the difference in the name and parameters.

To create a given flow rate, the internal diameter of the pipes is taken into account. For inch ordinary pipes, it is 27.1 mm, for reinforced 25.5 mm, the closest to 1 ". Pipelines are designated in conventional units of flow area DN (DN). It determines the parameters of the pipe clearance and is indicated in numerical values. sections are selected taking into account an increase in throughput characteristics by 40-60% with an increase in the index.If the external cross-section is known and the purpose of the structures, using the table of sizes, 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 real metric dimensions of 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 the water pipes - the volume of water passed per unit. time. It depends on the rate of flow of water. With its increase, the risk of pressure drop in the line increases. Throughput characteristics are calculated according to formulas, but when planning an intra-apartment wiring, pipes of certain parameters are taken.

For the plumbing system:

1.5cm (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).

Taking into account that the internal cross-section of half-inch polymer pipes varies from 11 to 13 mm, and one-inch - 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 laying the network at a long distance, a decrease in 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 indicators, in inches.
The 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 parameters:

1/2 inch pipeline - 1.27 cm;
3/4 '' - 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.

The following indicators are used to determine the thread diameter:

1/2 inch pipeline - 2.04 - 2.07 cm;
3/4 '' - 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.

Correspondence table of the diameter of steel pipes to polymer structures:

Steel pipe prices:

PP pipe diameter

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

Small - 0.5; 1; 1.5; 2; 2.5; 3.2; 4; five; 6.3 and 7.5 cm is used for heating systems, drainage and water supply in private buildings. An internal cross-section of 3.2 cm is most popular in multi-storey buildings.
Average - 8; nine; ten; eleven; 12.5; sixteen; 20; 25 and 31.5 cm is used for the arrangement of water supply and sewage systems, allowing you to change cast iron products with similar external parameters. Internal sizes of 8, 9 and 10 cm are ideal for chemical environments.
Large - 40 cm and more is used for arranging cold water supply and ventilation systems.

Pipes are marked in inches and mm. When choosing structures for plumbing and heating systems, the wall thickness is taken into account, which affects the conditional permeability of highways with the same external parameters. With an increase in its parameter, an increase in pressure in the water supply system is allowed. Small dimensions reduce the cost of purchasing material and water consumption.

PP pipes cost:

Video

Very often on the packaging (box) with a mixer, in the list of product characteristics, you can see the figure 3/8 "in the column" connection size ".

What is this size, and how will we connect the mixer if we buy it?

Connection size 3/8 ", corresponds to metric thread M10. Such dimensions are for the threaded connection of the connecting part of the flexible hose. On one side of such a hose, clad in a metal braid, a turnkey fitting of 10 or 11 millimeters and a thread at the end of 10 millimeters, or 9.5 millimeters, which corresponds to three-eighths of an inch.

They look like this.

First, a short fitting is screwed to the mixer, followed by a long one. This is so that the edges of the fittings and the thickening of the pressing do not interfere with each other.

There is an alternative option for reinforced flexible hose is bellows hoses for mixers. They are not much more expensive, but their service life is several times longer than the service life of a braided rubber hose. So if the usual flexible liner lasts 3-4 years, then the bellows up to 10 years.

At the second end, the flexible hose may have a thread instead of a nut, complete with mixers, more often there is still a nut, so make sure that if you have a nut at the outlet of your pipeline, you will need to purchase a nipple -