Correspondence table for metric and inch connecting dimensions of pipes, pipeline fittings, flanges

How much is this in inches - nominal diameter (DN) 6-450

Size (diameter) of the tap based on the diameter of steel water and gas pipes

The information provided below may be useful to you when carrying out repairs, replacing radiators, heated towel rails or installing a Hydrolock water leakage protection system. After all, in order to select a Hydrolock system, you need to know the diameter of the pipe and, based on this, select the diameter of the electric ball drive (BEP). It should be noted that steel and cast iron pipes are usually designated by their nominal diameter (internal passage), and polymer and copper pipes by their outer diameter. We won’t burden you with special technical terms, we’ll try to explain it in an accessible language.

How much is this in inches - nominal diameter (DN) 500-2200

*DN or DN can be indicated with a dimension of mm, for example “DN 50 mm”, but this is not entirely correct, it implies a dimensionless value.

Quite often, when calculating pipeline fittings, it is necessary to convert the diameter of flanges or pipes into inches. Based on the table data, the dimensions of the connecting elements will be:

• DN 6 - the size in inches is 1/8″ inch
• DN 8 - the size in inches is 1/4″ inch
• DN 10 - the size in inches is 3/8 inch
• DN 15 - the size in inches is 1/2 inch
• DN 20 - the size in inches is 3/4 inch
• DN 25 - the size in inches is 1 inch
• DN 32 - inch size is 1 1/4 inches
• DN 40 - inch size is 1 1/2 inches
• DN 50 - the size in inches is 2 inches
• DN 65 - inch size is 2 1/2 inches
• DN 80 - the size in inches is 3 inches
• DN 90 - inch size is 3 1/2 inches
• DN 100 - the size in inches is 4 inches
• DN 125 - the size in inches is 5 inches
• DN 150 - the size in inches is 6 inches
• DN 175 - the size in inches is 7 inches
• DN 200 - the size in inches is 8 inches
• DN 225 - the size in inches is 9 inches
• DN 250 - the size in inches is 10 inches
• DN 275 - size in inches is 11 inches
• DN 300 - the size in inches is 12 inches
• DN 350 - the size in inches is 14 inches
• DN 400 - the size in inches is 16 inches
• DN 450 - the size in inches is 18 inches
• DN 500 - the size in inches is 20 inches
• DN 600 - the size in inches is 24 inches
• DN 700 - the size in inches is 28 inches
• DN 800 - the size in inches is 32 inches
• DN 900 - the size in inches is 36 inches
• DN 1000 - the size in inches is 40 inches
• DN 1050 - the size in inches is 42 inches
• DN 1100 - the size in inches is 44 inches
• DN 1200 - the size in inches is 48 inches
• DN 1300 - size in inches is 52 inches
• DN 1400 - size in inches is 56 inches
• DN 1500 - the size in inches is 60 inches
• DN 1600 - size in inches is 64 inches
• DN 1700 - size in inches is 68 inches
• DN 1800 - the size in inches is 72 inches
• DN 1900 - size in inches is 76 inches
• DN 2000 - the size in inches is 80 inches
• DN 2200 - size in inches is 88 inches

Source: tehtab.ru

DN – Standard denoting nominal internal diameter.

PN – Standard indicating nominal pressure.

What is Du?

Du

– formed from two words: Diameter and Conditional. DN = DN. Du is the same as DN. It's just that DN is a more international standard. Du is the Russian-language representation of DN. Now it is absolutely necessary to abandon this name for Du.

What is DN?

DN

— Standardized representation of diameter. GOST 28338-89 and GOST R 52720

Nominal diameter DN

(nominal diameter; nominal bore; nominal size; nominal diameter; nominal bore): A parameter used for pipeline systems as a characteristic of the connected parts of the fittings.

Note - The nominal diameter is approximately equal to the internal diameter of the connected pipeline, expressed in millimeters and corresponding to the nearest value from a series of numbers adopted in the established order.

What is DN usually measured in?

According to the terms of the standard, it seems that it is not strictly tied to the unit of measurement (written in the documents). But it just means the diameter. And diameter is measured by length. And because the unit of length may be different. For example, inch, foot, meter and the like. For Russian documents we simply measure in mm by default. Although the documents say that it is still measured in mm. GOST 28338-89. But it does not have a unit of measurement:

How can it not, if it does? Can you write in the comments how to understand this phrase?

It seems that it has arrived... DN (diameter number expressed in millimeters). That is, it does not have a unit of measurement, but rather contains constant values ​​(digital discrete values ​​of the type: 15,20,25,32...). But it cannot be designated, for example, as DN 24. Because the number 24 is not in GOST 28338-89. There are strict values ​​in order like: 15,20,25,32... And only these need to be selected for designation.

DN is measured by the nominal diameter in mm (millimeter = 0.001 m). And if you see DN15 in Russian documents, this will mean an internal diameter of approximately 15 mm.

Conditional pass

- indicates that this is the internal diameter of the pipe, expressed in millimeters - conventionally. The term “Conventional” indicates that the diameter value is not exact. Conventionally, we assume that it is approximately equal to certain values ​​of the standard.

The nominal bore (nominal size) is understood as a parameter used for pipeline systems as a characteristic of the connected parts, such as pipeline connections, fittings and fittings. The nominal diameter (nominal size) is approximately equal to the internal diameter of the connected pipeline, expressed in millimeters.

According to the standard from: GOST 28338-89

It is customary to choose the numbers that have been agreed upon. And you shouldn’t come up with your own numbers with commas. For example, DN 14.9 would be a designation error.

Nominal diameter

approximately equal to the internal diameter of the connected pipeline, expressed in millimeters and corresponding to the nearest value from a series of numbers adopted in the prescribed manner.

These are the numbers:

For example,

if the real internal diameter is 13 mm, then we write it as: DN 12. If the internal diameter is 14 mm. then we accept the value DN 15. That is, we select the closest number from the list of the standard: GOST 28338-89.

If in projects it is necessary to indicate both the diameter and thickness of the pipe wall, then it should be indicated as follows: d20x2.2 where the outer diameter is 20 mm. And the internal diameter is equal to the difference in wall thickness. In this case, the internal diameter is 15.6 mm. GOST 21.206–2012

Alas, we have to submit to other people's standards

Any materials imported from abroad were most often developed using a different length dimension: Inch

Therefore, most often the dimensions are oriented to inches. Usually a quotation mark is written in place of the word inch.

1 inch = 25.4 mm. Which is the same 1” = 25.4 mm.

Dimensions table.

Usually a quotation mark is written in place of the word inch.

1/2 “ = 25.4 / 2 = 12.7. But in reality, this size of 1/2 “is equal to a passage of 15 mm. More precisely it might be 14.9mm. for steel pipe. In general, dimensions may vary by a few mm. Therefore, in such cases, for accurate calculations, you need to find out the internal diameter of a specific model separately.

For example, size 3/4” = 25.4 x 3/4 = 19 mm. But we write in the documents “conditionally” DN20 - approximately the internal diameter is 20 mm.

Here are the actual sizes that most often correspond to the Russian translation.

The table shows the internal diameter in mm.

Nominal pressure PN:

More details in GOST 26349 and GOST R 52720.

Has a unit of measurement: kgf/cm2. The designation kgf means kg x s (kilogram times s). c=1. c characterizes, as it were, a force coefficient. That is, by multiplying a kilogram (mass) by force, we convert mass into force. This is a correction for meticulous physicists. If you designate kg/cm2, in principle you will not be mistaken if you assume that we perceive mass as force. Also, such a unit as kg/cm2 is erroneous in that pressure is formed from two units (force and area). Mass is another parameter. Because the mass only on the surface of the earth creates the force that presses on the earth (gravitational force). Value c=1 on the surface of the earth. And if you fly to another planet, then the force of gravity will be different, and the mass will create a different force. And on another planet the coefficient c=1 will be equal to a different value. For example, c=0.5 will create pressure twice as low.

What is PN for?

The PN value is needed to indicate to the device a pressure limit that cannot be exceeded for normal operation of the device for which this value is set. That is, when designing, the designer must know in advance what maximum pressure the device is designed for.

For example,

if the device is given the value PN15, this means that the device is designed for operation with a pressure not exceeding 15 kgf/cm2. Which is approximately equal to 15 Bar.

1 kgf/cm2 = 0.98 Bar. Roughly speaking, the PN value is approximately equal to Bar or atmosphere.

For example, if a device is given a value of PN10, then it is designed for a pressure not exceeding 10 Bar.

Determination of PN according to the standard

The highest excess operating pressure at a working medium temperature of 293 K (20 °C), which ensures a given service life (resource) of valve body parts having certain dimensions, justified by strength calculations for the selected materials and their strength characteristics at a temperature of 293 K (20 °C).

Russian standards:

GOST 26349-84, GOST 356-80, GOST R 54432-2011

European standards:

DIN EN 1092-1-2008

American standards:

ANSI/ASME B16.5-2009, ANSI/ASME B16.47-2006

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