An inch thread is used primarily to create pipe connections: it is applied both to the pipes themselves and to the metal and plastic fittings necessary for the installation of pipe lines for various purposes. The main parameters and characteristics of the threaded elements of such connections are regulated by the relevant GOST, giving tables of sizes for inch threads, which specialists are guided by.
The normative document, which specifies the requirements for the dimensions of a cylindrical inch thread, is GOST 6111-52. Like any other, inch thread is characterized by two main parameters: pitch and diameter. The latter usually means:
Knowing the outer and inner diameters of an inch thread, you can easily calculate the height of its profile. To calculate this size, it is enough to determine the difference between such diameters.
The second important parameter - step - characterizes the distance at which two adjacent ridges or two adjacent depressions are located from each other. Throughout the entire section of the product on which the pipe thread is made, its pitch does not change and has the same value. If such an important requirement is not met, it will simply be inoperative, it will not be possible to pick up the second element of the created connection to it.
You can familiarize yourself with the provisions of GOST regarding inch threads by downloading the document in pdf format from the link below.
Learn how metric threads relate to various types inch threads, you can use the data from the table below.
Similar sizes of metric and various varieties of inch threads in the range of approximately Ø8-64mm
According to their external features and characteristics, metric and inch threads do not have many differences, the most significant of which include:
When comparing the shapes of threaded ridges, you can see that in inch threads such elements are sharper than in metric ones. If we talk about the exact dimensions, then the angle at the top of the crest of an inch thread is 55 °.
The parameters of metric and inch threads are characterized by different units of measurement. So, the diameter and pitch of the first are measured in millimeters, and the second, respectively, in inches. However, it should be borne in mind that in relation to an inch thread, not the generally accepted one (2.54 cm), but a special pipe inch, equal to 3.324 cm, is used. Thus, if, for example, its diameter is ¾ inch, then in terms of millimeters, it will correspond to a value of 25.
To find out the main parameters of an inch thread of any size, which is fixed by GOST, just look at a special table. In the tables containing the sizes of inch threads, both integer and fractional values \u200b\u200bare given. It should be borne in mind that the pitch in such tables is given in the number of cut grooves (threads) contained in one inch of the length of the product.
To check whether the pitch of the thread that has already been made corresponds to the dimensions specified by GOST, this parameter must be measured. For such measurements, carried out for both metric and inch threads according to one algorithm, standard tools are used - a comb, gauge, mechanical gauge, etc.
The easiest way to measure the pitch of an inch pipe thread is by using the following method:
If the bolt is not screwed into the template or is screwed, but creates a loose connection with it, then such measurements should be taken using a different coupling or other fitting. An internal pipe thread is also measured using a similar technique, only a product with an external thread is used as a template in such cases.
You can determine the required dimensions using a thread gauge, which is a plate with notches, the shape and other characteristics of which exactly match the parameters of the thread with a certain pitch. Such a plate, acting as a template, is simply applied to the thread being checked with its serrated part. The fact that the thread on the element under test corresponds to the required parameters will be indicated by the tight fit of the serrated part of the plate to its profile.
In order to measure the size of the outside diameter of an inch or metric thread, you can use a regular caliper or micrometer.
Cylindrical pipe thread, which belongs to the inch type (both internal and external), can be cut manually or mechanically.
Thread cutting by handThreading with hand tool, which is used as a tap (for internal) or a die (for external), is performed in several steps.
Thread cutting on a lathe
Mechanically, pipe threads are cut according to the following algorithm:
It should be borne in mind that the inch thread is cut mechanically using lathe only on tubular products, the thickness and rigidity of which allow this. Performing pipe inch threads mechanically allows you to get a high-quality result, but the use of this technology requires the turner to have appropriate qualifications and certain skills.
A thread related to the inch type, as indicated by GOST, can correspond to one of three accuracy classes - 1, 2 and 3. Next to the number indicating the accuracy class, put the letters "A" (external) or "B" (internal). The full designations of the thread accuracy classes, depending on its type, look like 1A, 2A and 3A (for external) and 1B, 2B and 3B (for internal). It should be borne in mind that the 1st class corresponds to the coarsest threads, and the 3rd - the most accurate, the dimensions of which are subject to very stringent requirements.
15512 2 3
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 measures of length and into the current regulatory documentation. So, let's go.
It is believed that Henry's sword was one yard long.
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.
Samples of pipe products produced in accordance with GOST 3262 - 75.
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 second standard indicates the dimensions of the crests and troughs of the thread in SI units, but designates cylindrical pipe threads in inches.
So, in order to correlate the pipe size in inches and mm, you need to overlay normative 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.
| 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.
| DU | External diameter | Wall thickness | ||
| 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.
Diameter is one of the most important dimensional characteristics steel pipes. Thanks to such a parameter as the 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 millimeters)
- and small diameter (no more than 114 millimeters).
It is according to these characteristics that the diameters of steel pipes are determined according to GOSTs and TUs:
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, as well as in inches.
| Nominal pipe diameter (Dy), mm | Thread diameter (G), inch | Pipe outer diameter (Dh), mm | ||
| Pipe steel water and gas | 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 |
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.
When choosing the necessary products, regardless of what material they are made of, a number of indicators should be taken into account:
There are two methods of measurement, the emergence of which has historical roots:
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.
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 for an inch product it is 55, and for a metric product it is 60. 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.
If necessary, you can use the special reference literature containing the relevant 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.
In the construction market, 2 sizes of structures are popular:
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). There is an exception in the range of steel structures - 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).
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.
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 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 internal 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 conditional flow section is selected taking into account the increase in throughput characteristics by 40-60% with an increase in the index. If the external cross-section and the purpose of the structures are known, the internal cross-section is determined using the dimension table.
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.
To compare the range of pipes according to GOST RF and European standards, the following table is used:
From diameter water pipes their throughput characteristics depend - 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 laying the network at a great 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:
The cross section of the pipes corresponds to a number of indicators:
The internal cross section of pipes with different threads corresponds to the following parameters:
The following indicators are used to determine the thread diameter:
Table of correspondence between the diameter of steel pipes and polymer structures:
Steel pipe prices:
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.
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 in the plumbing system is allowed. Small dimensions allow to reduce the level of costs for the purchase of material and water consumption.
Inch pipe - dimensions in mm and 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 sealed high-quality assembly is the correspondence between the diameter of the pipe and the size of the connecting element.
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 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 it is important to know exactly the thread indicators for installation, this 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.
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.
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.
The presence of two methods of measurement has historical roots.
When joining conduits from different materials, difficulties arise with the recalculation from one system to another.
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 for different section sizes.
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.
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 of the 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.
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?
A huge assortment of steel pipes for various purposes, designs, types is presented in the form of tables, where the main parameters are:
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 polymer products are usually measured in millimeters, which creates some difficulties when joining metal-plastic, cast-iron, copper pipes with steel pipes 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 be up to 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 practical measurements of steel pipes show, 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.
The generally accepted standard values for 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
The main parameter characterizing a steel pipe is the diameter of an inch pipe. This characteristic indicates the scope of this pipe, the length of the pipeline, the composition and physical parameters of the substance transported through it. All diameter values must comply with standardization regulations that relate to standard sizes, all requirements for these products are carefully regulated by GOST. Each type of pipe has its own standard.
Dimensions are indicated on the marking: for steel - in inches, for others - in millimeters. How to find out the diameter of a steel pipe in mm? Here tables of diameters of steel products will come to the rescue.
Diameter is not the only characteristic by which steel pipes differ, an equally important parameter is the method of their production, which is also a key point when choosing them.
Regarding diameters, it is worth noting that regulations control their production up to a value of 250 mm. When purchasing products whose diameter is greater than the specified one, you only have to trust the integrity of the manufacturer.
It's important to know! If you need the most durable pipes, the best option there will be a purchase of seamless deck molding products. The initial characteristics of the metal do not change due to the effects of temperature, which has a positive effect on strength.
Also, if the key requirement is the ability to withstand internal pressures, round-shaped products are most suitable for this role. Profile pipes more resistant to mechanical stress (they are well suited for the manufacture of various kinds of frames, load-bearing structures).
Theoretically, the diameter of the pipe is quite simply added to any calculations during the determination of certain values. But in reality, everything is much more complicated - there is a wall thickness, the diameter differs in nominal, internal and external. What concepts exist and their meaning:
A large assortment of steel pipes for various purposes, manufacture, types is presented in the form of tables. It happens that in the table of diameters of steel pipes, the values \u200b\u200bof the masses of the product are entered depending on its dimensions, as well as the values of the nominal diameter.
Pipes whose diameter is defined in inches (1"", 2"") and/or fractions of an inch (½'', ¾"), the generally accepted standard for water and gas supply.
Pipes that are used for gas or water mains are usually measured in inches and not in millimeters. The inch diameter of the pipe is 33.5 mm (see table), but the SI inch is 24.4 mm. The thing is that the size of the pipes is determined by the inner diameter, and not by the outer diameter.
Measure a diameter of 1 '' (how to measure pipes is described below) and you will have a value of 33.5 mm, which of course will contradict the classic linear unit conversion table.
Usually installation inch pipes does not cause any problems. But during their replacement with plastic, copper or stainless steel, a problem arises - the discrepancy between the indicated inch value and its real value. Usually such a discrepancy is perplexing, but if you look deeper into the processes that occur in the pipe, then everything falls into place.
The whole point is that during the creation of a water flow, the main role is given to the inner, and not the outer diameter, and because of this, it is used as a designation. But the discrepancy with the usual designation system still remains, since the inner diameter of a conventional pipe is 27.1 mm, and that of a reinforced pipe is 25.5 mm. The latter is not far from the equality that one inch is equal to 25.4, but still it is not.
The thing is that pipes are designated by a nominal diameter, which is rounded up to a standard value (nominal diameter Dy).
Suppose the outer diameter of the pipe is 159 mm with a wall thickness of 7 mm, in this case the exact inner diameter will be the following value, which can be calculated using the formula D \u003d 159 - 7 * 2 \u003d 145 mm. With a wall thickness of 5 mm, the diameter will be 149 mm. But in both the first and second cases, the conditional passage will be the same and will be equal to 150 mm.
In cases with plastic pipes in order to solve the problem of inappropriate dimensions, transition elements are used. If it is necessary to replace or join inch pipes with pipes that have real metric dimensions, made from materials such as aluminum, copper, stainless steel, both the inner and outer diameters must be taken into account.
Nominal bore table in inches:
| Conventional diameter | inches | Conventional diameter | inches | Conventional diameter | inches |
| 6 | 1/8" | 150 | 6" | 900 | 36" |
| 8 | ¼" | 175 | 7" | 1000 | 40" |
| 10 | 3/8" | 200 | 8" | 1050 | 42" |
| 15 | ½" | 225 | 9" | 1100 | 44" |
| 20 | ¾" | 250 | 10" | 1200 | 48" |
| 25 | 1" | 275 | 11" | 1300 | 52" |
| 32 | 1 (¼)" | 300 | 12" | 1400 | 56" |
| 40 | 1 (½)" | 350 | 14" | 1500 | 60" |
| 50 | 2" | 400 | 16" | 1600 | 64" |
| 65 | 2(½)" | 450 | 18" | 1700 | 68" |
| 80 | 3" | 500 | 20" | 1800 | 72" |
| 90 | 3 (½)" | 600 | 24" | 1900 | 76" |
| 100 | 4" | 700 | 28" | 2000 | 80" |
| 125 | 5" | 800 | 32" | 2200 | 88" |
The size of the nominal passage is selected in such a way that the throughput of the pipeline increases from 40 to 60%, depending on the increase in the index value.
Quite often, in many sources you can find a phrase like “We take any pipe of medium diameter ...”, but no one indicates the specific values \u200b\u200bof this diameter. To understand this issue, you first need to decide on what diameter you need to build on: it can be both internal and external. The first is of great importance when calculating the transport characteristics of water or gas, and the second determines the ability to withstand mechanical loads.
External diameters:
If the conversation is about the inner diameter, then it is better to check with a special table.
Correspondence table for the diameter of the nominal bore, thread and outer diameters of the pipeline in inches and mm:
| Nominal pipe diameter Dy. mm | Thread diameter G". inch | Outer pipe diameter Dn. mm | ||
| Pipes steel water / gas pipeline GOST 3263-75 | Pipes steel electrowelded longitudinal GOST 10704-91. Pipes steel seamless hot deformed GOST 8732-78. GOST 8731-74) | polymer pipe. PE, PP, PVC | ||
| 10 | 3/8" | 17 | 16 | 16 |
| 15 | ½" | 21.3 | 20 | 20 |
| 20 | ¾" | 26.8 | 26 | 25 |
| 25 | 1" | 33.5 | 32 | 32 |
| 32 | 1¼" | 42.3 | 42 | 40 |
| 40 | 1½" | 48 | 45 | 50 |
| 50 | 2" | 60 | 57 | 63 |
| 65 | 2½" | 75.5 | 76 | 75 |
| 80 | 3" | 88.5 | 89 | 90 |
| 90 | 3½" | 101.3 | ||
| 100 | 4" | 114 | 108 | 110 |
| 125 | 5" | 140 | 133 | 125 |
| 150 | 6" | 165 | 159 | 160 |
| 160 | 6½" | 180 | 180 | |
| 200 | 219 | 225 | ||
| 225 | 245 | 250 | ||
| 250 | 273 | 280 | ||
| 300 | 325 | 315 | ||
| 400 | 426 | 400 | ||
| 10 | 3/8" | 17 | 16 | 16 |
GOST - state standard used in heat - gas - oil - pipelines
ISO - standard for designating diameters, used in plumbing engineering systems
SMS - Swedish standard for pipe and valve diameters
DIN / EN - the main European range for steel pipes according to DIN2448 / DIN2458
DU (Dy) - conditional pass.
Most often, during the acquisition, you can simply ask a consultant a question or look at the marking. But it happens that one of the communication systems needs repair and replacement of pipes, and it is not known what diameter is already installed pipes. There are several ways to determine the diameter, but we will talk about the simplest:
Using a tape measure or centimeter tape, wrapping it around the pipe, write down the resulting value. Now, in order to find out the diameter, you need to divide the obtained data by the number Pi (3.1415).
Let's say that the pipe has a girth of 6 cm. Its diameter is calculated as follows: 6 x 3.1415 = 18.85 mm. After the outer diameter is obtained, the inner diameter can also be calculated. For this calculation, we need to know the wall thickness (if there is a cut, measure it with any measuring tool with millimeter graduation). For example, the walls have a thickness of 1mm. This figure is multiplied by 2 (even with a thickness of 3 mm it is still multiplied by 2) and subtracted from the outer diameter.
As a sample, you can give the following calculation: (18.85- (2 x 1 mm) \u003d 16.85 mm).
Diameters and other characteristics of stainless steel pipe:
| Pass, mm | Outer diameter, mm | Wall thickness, mm | Weight of 1 m pipe (kg) | ||
| standard | enhanced | standard | enhanced | ||
| 10 | 17 | 2.2 | 2.8 | 0.61 | 0.74 |
| 15 | 21.3 | 2.8 | 3.2 | 1.28 | 1.43 |
| 20 | 26.8 | 2.8 | 3.2 | 1.66 | 1.86 |
| 25 | 33.5 | 3.2 | 4 | 2.39 | 2.91 |
| 32 | 42.3 | 3.2 | 4 | 3.09 | 3.78 |
| 40 | 48 | 3.5 | 4 | 3.84 | 4.34 |
| 50 | 60 | 3.5 | 4.5 | 4.88 | 6.16 |
| 65 | 75.5 | 4 | 4.5 | 7.05 | 7.88 |
| 80 | 88.5 | 4 | 4.5 | 8.34 | 9.32 |
| 100 | 114 | 4.5 | 5 | 12.15 | 13.44 |
| 125 | 140 | 4.5 | 5.5 | 15.04 | 18.24 |
| 150 | 165 | 4.5 | 5.5 | 17.81 | 21.63 |
A very good help in this matter is the caliper. The pipe is simply wrapped around the measuring teeth and looked at the value obtained on the scale.
According to the tables, the diameters of plastic, brass and copper pipes are thus determined. The method of converting inch to metric dimensions is used when joining products made from different materials. In the case when there are fittings for gas or water pipes made of steel, installation becomes much easier - the connecting elements take this feature into account.
