The description of pipe diameters contains data on all parameters - internal, external, conditional, nominal. Knowledge of the characteristics is required when installing the network and selecting fittings. Otherwise, incorrectly assembled communications threaten loss of tightness and a short service life due to breakdowns. Next, consider the pipe diameters in inches and millimeters.
Dimensional characteristics of pipes
They are reflected in the relevant GOSTs and TUs and contain the following definitions:
- The outer diameter is the main characteristic of the pipe.
- Inner diameter.
- Nominal.
- Conditional pass.
More details about the differences:
- Outside diameter classified into small, medium and large values - which is why the pipe is used in the appropriate conditions. Small diameter is used in residential and private water supply systems, medium diameter is used in city communications, large diameter is used in industrial ones. The outer diameter is the most important characteristic of the pipe, since it determines the required fitting thread. Designation – Dн.
- Inner diameter or true. It depends on the thickness of the wall and can differ strikingly from the external one, even if the dimensions of the latter remain unchanged. Designated as Din. It is calculated mathematically (Dн – 2S), where S is the thickness of the pipe wall. Example - the outer diameter of the pipe is 60 mm. Minus the 4 mm walls, its internal diameter will be 52 mm. As the wall thickness increases, the internal parameter decreases.
- The nominal bore or diameter of the pipe lumen is marked as Dу. This is the average internal diameter, rounded up to the standard value. For example, the outer diameter of the pipe will be 159 mm. The true internal diameter after subtracting the wall thickness of 5 mm is 149. Then the nominal diameter after rounding is 150 mm. This parameter is considered to select suitable fittings and fittings.
- Nominal diameter. The concept was introduced to standardize the marking of pipes made of different materials. The value is equal to the nominal diameter and is marked in inches. This allows you to correctly select pipes from various raw materials for combining in a network - steel and plastic are marked in inches, copper and aluminum - in millimeters.
Thus, the correct selection of components for home communications in accordance with the described concepts is not difficult. Tables for converting sizes from inches to millimeters and vice versa will help in self-repair and replacement of defective sections of networks.
Table of diameter sizes in diameters and millimeters
|
Nominal diameter (Dy) of the pipe, in mm |
The diameter of its thread (G), in inches |
Outer diameter (Dh), pipes, mm |
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|
Steel seam pipe, water and gas supply |
Seamless steel pipe |
Polymer pipe |
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Complete table of pipe diameters
| Diameters, inch | Diameters, mm |
| 1/2 | d15 |
| 3/4 | d20 |
| 1' | d25 |
| 1’/1/4 | d32 |
| 1’/1/2 | d40 |
| 2′ | d50 |
| 2’/1/2 | d65 |
| 3′ | d89 |
| 4' | d100 |
| Inch | Millimeter | Inch | Millimeter |
| 1/64 | 0,397 | 33/64 | 13,097 |
| 1/32 | 0,794 | 17/32 | 13,494 |
| 3/64 | 1,191 | 35/64 | 13,891 |
| 1/16 | 1,587 | 9/16 | 14,287 |
| 5/64 | 1,984 | 37/64 | 14,684 |
| 3/32 | 2,381 | 19/32 | 15,081 |
| 7/64 | 2,778 | 39/64 | 15,478 |
| 1/8 | 3,175 | 5/8 | 15,875 |
| 9/64 | 3,572 | 41/64 | 16,272 |
| 5/32 | 3,969 | 21/32 | 16,669 |
| 11/64 | 4,366 | 43/64 | 17,066 |
| 3/16 | 4,762 | 11/16 | 17,462 |
| 13/64 | 5,159 | 45/64 | 17,859 |
| 7/32 | 5,556 | 23/32 | 18,256 |
| 15/64 | 5,953 | 47/64 | 18,653 |
| 17/64 | 6,747 | 49/64 | 19,447 |
| 9/32 | 7,144 | 25/32 | 19,844 |
| 19/64 | 7,541 | 51/64 | 20,241 |
| 5/16 | 7,937 | 13/16 | 20,637 |
| 21/64 | 8,334 | 53/64 | 21,034 |
| 11/32 | 8,731 | 27/32 | 21,431 |
| 23/64 | 9,128 | 55/64 | 21,828 |
| 3/8 | 9,525 | 7/8 | 22,225 |
| 25/64 | 9,922 | 57/64 | 22,622 |
| 13/32 | 10,319 | 29/32 | 23,019 |
| 27/64 | 10,716 | 59/64 | 23,416 |
| 7/16 | 11,112 | 15/16 | 23,812 |
| 29/64 | 11,509 | 61/64 | 24,209 |
| 15/32 | 11,906 | 31/32 | 24,606 |
| 31/64 | 12,303 | 63/64 | 25,003 |
According to their shape, pipes can be not only round, but also oval, rectangular, and square. Despite such diversity in cross-sectional shape, all pipes have mainly two types of parameters: technical and geometric. The geometric dimensions of pipes are represented by such characteristics as outer diameter, wall thickness or the ratio of outer and inner diameters, and length. , that is, pipe sizes are standardized by state standards (GOSTs). Different GOSTs are developed for pipes not only with different manufacturing methods, but also for different materials used in the production of pipes. In the Russian market, it is mainly customary to indicate pipe sizes in mm (millimeters), but you can also find pipe sizes in inches. The latter are most often indicated for imported pipes. The length of rolled pipe is usually measured in meters.
The most common and popular are the following pipe sizes (diameter from largest to smallest): 1420, 1220, 1020, 920, 820, 720, 530, 426, 377, 325, 273, 219, 159. This rolled product applies to large and medium pipes diameter Smaller diameters are in much less demand on the market, so, of course, you can find them, but you have to try. On the manufacturer’s website there will definitely be a table of pipe sizes that the company produces. Typically, any manufacturer tries to cover as wide a range of pipe sizes as possible, since in our time the demand market for this type of rolled product is very wide.
Until recently, Russian production has not produced seamless pipes with a diameter of more than 426 mm. But electric welded ones cover almost the entire range. Spiral-welded pipes can have a diameter greater than 1420, but less than 159 - they are not produced. With straight-seam pipes things are different. According to GOST, the smallest diameter of a straight-seam pipe is 8 mm, and the largest is 1420 mm. This is due to the fact that spiral-seam and straight-seam pipes have different manufacturing methods, although both of them are welded pipes.
Pipe sizes are not limited to one diameter. Wall thickness is also one of the important technical indicators. Moreover, the diameter directly affects the size of the pipes, such as wall thickness. The larger diameter allows pipes to be manufactured with a wider range of wall thicknesses. For example, if the dimensions of straight-seam metal pipes (or rather, their diameter) are 530 cm, then the wall thickness can vary from 5 to 24 mm. The outer transverse dimensions of longitudinal steel pipes of 1020 mm make it possible to manufacture them with wall thicknesses from 8 mm to 32 mm. The most popular for pipes, for example, with a diameter of 530 mm, are wall thicknesses such as 7, 8, 9 and 10 mm. For a pipe with a diameter of 1020 mm, the most common thicknesses are 10, 11, 12, and 14 mm.
It is interesting that GOST allows manufacturers to violate pipe dimensions within certain limits. In particular, for a straight-seam pipe with a diameter of 1020 mm, the deviation in wall thickness can reach almost 1 mm. More precisely - 0.8 mm, both in the direction of greater and lesser thickness. And since the range of pipes is determined in increments of 1 mm in thickness, this value is quite significant. For example, when buying a pipe with a thickness of 11 mm, do not be surprised that when measured directly it turns out to be a pipe with walls of 10 or 12 mm. This aspect is very important when purchasing pipes, since the weight of the rolled product depends on the size of the pipes and the wall thickness. More weight - more price. Why is it customary to indicate weight and not footage? Because the cost of a pipe mainly depends on the raw materials (the so-called price-forming raw material component).
Of course, weighing a pipe is too troublesome. Therefore, when calculating the price, the theoretical weight is taken into account, which is calculated using the formula: weight of 1 linear meter = 0.02466 * wall thickness * (diameter - wall thickness). The wall thickness is taken in millimeters. In practice, the calculation is made as follows: the buyer measures the thickness of the pipes with a micrometer in order to check the deviation from the permissible values. When loading, use a tape measure to measure the longitudinal dimensions of the pipes (i.e. length) and then, calculating the theoretical weight of 1 linear meter. multiply it by the total length of the pipes.
In relation to these sizes of steel pipes, as well as to the sizes of pipes made of any other material, the GOST requirements are quite loyal. For example: “pipes with a diameter of over 152 mm are manufactured with a length of at least 5 m.” Therefore, despite the fact that used pipes are cut a little before sale, it is impossible to distinguish them by length from new ones. It is worth remembering that when selling straight or spiral-welded pipes, many do not indicate the length. This means that the length of the pipes complies with GOST standards (usually approximately 11 meters). If the price list (advertisement) indicates that the pipes are sold cut at the seams, then their lengths are also within the limits allowed by GOSTs. Seamless pipes are allowed to be manufactured in unmeasured lengths - from 4 meters to 12.5. Therefore, when purchasing pipes, take an interest in GOST standards.
Steel pipe diameters
The diameter of a steel pipe is determined by the outer diameter for electric-welded and seamless pipes, and for VGP - by the nominal diameter (often designated as DN). That is, internal diameter of pipes- Dу, outer diameter of pipes Dн, thread diameter - G. Pipe sizes are specified in millimeters, but VGP pipes are often designated in inches (").
VGP pipe size (GOST 3262-75)
Main pipe dimensions: 15 mm (1/2" inch); 20 mm (3/4"); 25 mm (1"); 32 mm (1 1/4" inches and a quarter); 40 mm (1 1/2"); 50 mm (2"). There are also the following DNs: 10 mm, 65 mm, 80 mm, 90 mm, 100 mm and even 125 mm - but they are rarely used and, as a rule, are replaced by other types of steel pipes (for example, electric welded). Most often, 3/4" pipes are used for risers; 1/2" internal wiring is used.
Electrical pipes (GOST 10704-91)E/s straight-seam pipes come in the following outer diameters (in millimeters): 10; 12; 13; 14; 16; 17; 17.5; 18; 19; 20; 21.3; 22; 24; 25; 26; 28; thirty; 32; 33; 33.7; 36; 38; 40; 42; 43; 45; 48; 51. For diameters up to 57 mm, a VGP pipe of the appropriate size is used. The most popular are straight-seam pipes in accordance with GOST 10704-91 with sizes of 57 mm and above. Their main diameters: 57; 60; 63.5; 76; 89; 102; 108; 114; 127; 133; 140; 146; 159; 168; 178; 193; 219; 245; 273; 325; 377; 426; 530.
Welded pipes for gas and oil pipelines (GOST 20295-85)They start with a diameter of 159 mm and up to 530 mm come with the same dimensions as pipes according to GOST 10704-91. Basic larger diameters (in millimeters): 630, 720, 820, 1020,1220, 1420.
Size of hot-rolled seamless pipes (GOST 8732-78)Commonly used diameters of seamless hot-formed pipes (mm): 32; 38; 42; 45; 51; 54; 57; 60; 63,5; 68; 70; 73; 76; 83; 89; 95; 102; 108; 114; 121; 127; 133; 140; 146; 152; 159; 168; 180; 194; 203; 219; 245; 273; 325; 351; 426.
Manufacturers can produce any pipe sizes according to customer requirements.
Pipe internal diameters
According to the standard series adopted in most countries, pipes have the following internal diameters, measured in mm: 6, 10, 15, 20, 25, 32, 40, 50, 65, 80, 100, 125, 200, etc.
A system of measuring thread diameter in inches is also used. 1" = 25.4 mm.
The table shows pipe sizes(diameters) in mm and inches:
|
Nominal pipe bore (Dy) mm |
Thread diameter (G), inch |
Pipe outer diameter (Dн), mm |
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|
Steel water and gas pipe |
Seamless |
Polymer |
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When installing a system of steel pipes for residential buildings, pipes with an internal diameter size of Dу = 15, 20 and 32 mm are usually used.
Cast iron non-pressure pipes with diameter Dу = 50 and 100 mm are the most commonly used.
Currently, pipes made of polymer materials are increasingly used for laying intra-house pipelines, which are replacing cast iron and steel.
It should be noted that depending on the type of material used in the manufacture of pipes, different designation systems are used. In most cases, steel and cast iron pipes are designated by nominal diameter or internal diameter. Copper pipes, some types of steel pipes, and pipes made of polymer materials are designated by their outer diameter. Therefore, you should be careful when choosing the required pipe, and also take into account the wall thickness.
Pipe outer diameters and pipe wall thickness
|
Outer diameter, Dн mm |
Wall thickness, mm |
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|
Steel water and gas pipes GOST 3262-75 |
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Electric welded steel pipes GOST 10704-91 GOST 10705-80 |
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|
Plastic pipes |
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Typically, the designation of pipe diameters uses values in inches, so we invite you to familiarize yourself with the table where the values in inches are converted to millimeters. In the scientific literature, the concept of “conditional passage” is used.
Under "conditional passage" understand a value (conventional diameter) that conventionally characterizes the internal diameter and does not necessarily coincide with the actual internal diameter. Conditional passage is taken from the standard range
1inch = 25.4 mm
Please note that if we take a 1" (one inch) pipe, then the outer diameter is not equal to 25.4 mm. This is where the confusion begins -"pipe inches". Let's try to clarify this issue. If you look at the parameters of a cylindrical pipe thread, you will notice that the outer diameter (at one inch) is 33.249 mm, not 25.4.
The nominal diameter of the thread is conventionally related to the internal diameter of the pipe, and the thread is cut on the outer diameter. So we get a diameter of 25.4 mm + two pipe wall thicknesses ≈ 33.249 mm. Thus appeared"pipe inch".
| Diameters in inches | Accepted nominal pipe diameters, mm | External dimensions of steel pipe according to GOST 3262-75, mm |
| ½ " | 15 | 21,3 |
| ¾ " | 20 | 26,8 |
| 1 " | 25 | 33,5 |
| 1 ¼ " | 32 | 42,3 |
| 1 ½ " | 40 | 48 |
| 2 " | 50 | 60 |
| 2 ½" | 65 | 75,5 |
| 3 "" | 80 | 88,5 |
| 4 " | 100 | 114 |
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TECHINFO section on the website "Converting plumbing inches to millimeters"
It seems that you can simply measure the diameter of the pipe and convert it to standard inches (25.4 mm). But the result will be incorrect. 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 will decide that this is an inch pipe with a slight deviation. But it's actually 3/4 inch pipe.
Convert plumbing inches to millimeters
The size of water and gas pipes is usually indicated in inches and fractions of an inch. This is how it happened historically. And for an ignorant person, converting these sizes into metric ones is quite difficult. Let's try to figure this out...
The problem of converting inch pipe sizes into metric (millimeters) often arises when replacing steel pipes with plastic, metal-plastic or copper. The size of these pipes is indicated in millimeters. Errors in selection are unacceptable. If you install a pipe with a smaller diameter, the water pressure will drop. Anything more and the extra money will be wasted.
It seems that you can simply measure the diameter of the pipe and convert it to standard inches (25.4 mm). But the result will be incorrect. For example, a pipe with an outside diameter of 26.8 mm when converted to standard inches will give 1.06 inches. A person unfamiliar with the intricacies of plumbing will decide that this is an inch pipe with a slight deviation. But it's actually 3/4 inch pipe.
The trick here is that for pipes, the internal diameter is important, which determines the throughput of the pipe. And the inch size determines the parameters of threads cut on pipes, bends, couplings, elbows, tees, valves and other fittings. Therefore, to convert inch pipe sizes to metric, you need to use the table.
The equivalent diameter determines the nominal diameter of the pipe, providing the same throughput as the corresponding inch one.
Diameter is one of the most important dimensional characteristics of steel pipes. Thanks to such a parameter as diameter, all the necessary design calculations can be made.
Standard diameters of steel pipes are strictly regulated by GOST 10704-91.
Purely conditionally, pipe diameters are divided into the following categories:
- large diameter (more than 508 millimeters),
- medium diameter (114-530 mm)
- and small diameter (no more than 114 millimeters).
Main dimensions
It is based on these characteristics that the diameters of steel pipes are determined in accordance with GOSTs and TUs:
- internal diameter of pipes;
- the outer diameter of the pipes is their main dimensional characteristic according to GOST standards;
- nominal pipe diameter. Represents the nominal size of the internal diameter of the pipe;
- pipe wall thickness;
- nominal pipe diameter.
- Steel pipes are classified into small, medium and large precisely according to the outer diameter (Dн). Standard diameters are shown in the table.
- The most commonly used steel pipes are the following diameters: 426, 530, 159, 219, 720, 920, 273, 325, 1420 and 1220 millimeters.
- The small outer diameter of steel pipes is used for the construction of water supply systems in apartments, houses and other premises.
- Medium-diameter steel pipes are used for the installation of city water pipelines, as well as in field crude oil collection systems.
- The largest diameter steel pipes are needed for the construction of main gas and oil pipelines.
Internal diameters of steel pipes
- The internal diameter of steel pipes (Din) with a constant external diameter can vary significantly. To standardize the diameter of pipes, a term such as “nominal bore (diameter)” is used. It is designated Dу.
- The nominal diameter is the rounded nominal size of the internal diameter. It is always rounded up only. The nominal diameter of steel pipes is determined by GOST 355-52.
- The internal diameter can be calculated using the following formula: Din = Dn - 2S.
- Steel pipes have internal diameters: 6, 15, 10, 20, 25, 50, 65, 32, 40, 80, 100, 125, 200.
Diameters of steel pipes in inches
In addition to millimeters, the diameter of steel pipes can also be measured in inches. One inch equals 25.4 millimeters. The table shows the diameters of steel pipes in millimeters and also in inches.
| Nominal diameter of the pipe (Dy), mm | Thread diameter (G), inch | Pipe outer diameter (Dh), mm | ||
| Steel water and gas pipe | Seamless | 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 | 169 | 160 |
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