Her Majesty Trumpet! It certainly makes our lives better. More or less like this:
The key characteristic of any cylindrical pipe is its diameter. It may be internal Do) and outer ( Dn). Pipe diameter is measured in millimeters, but the unit of pipe thread is inch.
At the junction of the metric and foreign systems of measurement, as a rule, the most questions arise.
In addition, the actual size of the inner diameter often does not match Dy.
Let's take a closer look at how we can live with this. A separate article is devoted to pipe threading. Read also about profile pipes, which are used for the construction of structures.
Inches versus mm. Where does the confusion come from and when is a correspondence table needed?
Pipes whose diameter is indicated in inches ( 1", 2" ) and/or fractions of an inch ( 1/2", 3/4" ), are the generally accepted standard in water and water and gas supply.
What is the difficulty?
Dimension the pipe diameter 1" (how to measure pipes is written below) and you will get 33.5mm, which naturally does not coincide with the classic linear table for converting inches to mm ( 25.4mm).
As a rule, installation of inch pipes takes place without difficulty, but when they are replaced with pipes made of plastic, copper and stainless steel, a problem arises - a mismatch in the size of the designated inch ( 33.5mm) to its actual size ( 25.4mm).
Usually this fact is puzzling, but if you look deeper into the processes taking place in the pipe, then the logic of the size mismatch becomes obvious to the non-professional. It's pretty simple - read on.
The fact is that when creating a water flow, the key role is played not by the outer, but by the inner diameter, and for this reason it is he who is used for designation.
However, the discrepancy between designated and metric inches still remains, because the internal diameter of a standard pipe is 27.1 mm, and enhanced - 25.5mm. The last value is pretty close to equality 1""=25,4 but still they are not.
The answer is that to indicate the size of the pipes, a nominal diameter rounded to a standard value is used (nominal bore Dy). The value of the conditional passage is chosen so that throughput pipeline increased from 40 to 60% depending on the growth of the index.
Example:
The outer diameter of the pipe system is equal to 159 mm, pipe wall thickness 7 mm. The exact inside diameter will be D \u003d 159 - 7 * 2 \u003d 145 mm. With wall thickness 5 mm size will be 149 mm. However, both in the first and in the second case, the conditional passage will have one nominal size 150 mm.
In situations with plastic pipes transition elements are used to solve the problem of inappropriate sizes. If it is necessary to replace or join inch pipes with pipes made according to real metric dimensions - copper, stainless steel, aluminum, both the outer and inner diameters should be taken into account.
Nominal bore table in inches
| Doo | inches | Doo | inches | Doo | inches |
| 6 | 1/8" | 150 | 6" | 900 | 36" |
| 8 | 1/4" | 175 | 7" | 1000 | 40" |
| 10 | 3/8" | 200 | 8" | 1050 | 42" |
| 15 | 1/2" | 225 | 9" | 1100 | 44" |
| 20 | 3/4" | 250 | 10" | 1200 | 48" |
| 25 | 1" | 275 | 11" | 1300 | 52" |
| 32 | 1(1/4)" | 300 | 12" | 1400 | 56" |
| 40 | 1(1/2)" | 350 | 14" | 1500 | 60" |
| 50 | 2" | 400 | 16" | 1600 | 64" |
| 65 | 2(1/2)" | 450 | 18" | 1700 | 68" |
| 80 | 3" | 500 | 20" | 1800 | 72" |
| 90 | 3(1/2)" | 600 | 24" | 1900 | 76" |
| 100 | 4" | 700 | 28" | 2000 | 80" |
| 125 | 5" | 800 | 32" | 2200 | 88" |
Table. Inner and outer diameters. Stacked water/water and gas pipelines, electro-welded straight-seam, steel seamless hot-formed and polymer pipes
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 |
||
|
Stacked water/water/gas pipes GOST 3263-75 |
Pipes steel electrowelded longitudinal GOST 10704-91. Pipes steel seamless hot deformed GOST 8732-78. GOST 8731-74 (from 20 to 530 ml) |
polymer pipe. PE, PP, PVC |
||
GOST- state standard used in heat - gas - oil - pipelines
ISO- diameter designation standard, used in plumbing engineering systems
SMS- Swedish standard for pipe and valve diameters
DIN/EN- the main European assortment for steel pipes according to DIN2448 / DIN2458
DU (Dy)- conditional pass
Dimension tables polypropylene pipes presented in the following article >>>
Correspondence table for the nominal diameter of pipes with international markings
| GOST | ISO inch | ISO mm | SMS mm | DIN mm | DU |
| 8 | 1/8 | 10,30 | 5 | ||
| 10 | 1/4 | 13,70 | 6,35 | 8 | |
| 12 | 3/8 | 17,20 | 9,54 | 12,00 | 10 |
| 18 | 1/2 | 21,30 | 12,70 | 18,00 | 15 |
| 25 | 3/4 | 26,90 | 19,05 | 23(23) | 20 |
| 32 | 1 | 33,70 | 25,00 | 28,00 | 25 |
| 38 | 1 ¼ | 42,40 | 31,75 | 34(35) | 32 |
| 45 | 1½ | 48,30 | 38,00 | 40,43 | 40 |
| 57 | 2 | 60,30 | 50,80 | 52,53 | 50 |
| 76 | 2½ | 76,10 | 63,50 | 70,00 | 65 |
| 89 | 3 | 88,90 | 76,10 | 84,85 | 80 |
| 108 | 4 | 114,30 | 101,60 | 104,00 | 100 |
| 133 | 5 | 139,70 | 129,00 | 129,00 | 125 |
| 159 | 6 | 168,30 | 154,00 | 154,00 | 150 |
| 219 | 8 | 219,00 | 204,00 | 204,00 | 200 |
| 273 | 10 | 273,00 | 254,00 | 254,00 | 250 |
Diameters and other characteristics of stainless steel pipe
| Pass, mm | Diameter outer, 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 | |
Did you know?
What ingenious lamps can be assembled with your own hands from an ordinary metal pipe? This is for everyone!
Which pipe is considered small - medium - large?
Even in serious sources, I had to observe phrases like: “We take any pipe of medium diameter and ...”, but no one indicates what this average diameter is.
To figure it out, you should first understand what diameter you need to focus on: it can be internal and external. The first is important when calculating the transport capacity of water or gas, and the second for determining the ability to withstand mechanical loads.
External diameters:
From 426 mm is considered large;
102-246 is called the average;
5-102 is classified as small.
As for the inner diameter, it is better to look at a special table (see above).
How to find out the pipe diameter? Measure!
For some reason, this strange question often comes to e-mail and I decided to supplement the material with a paragraph about metering.
In most cases, when buying, it is enough to look at the marking or ask the seller a question. But it happens that you need to repair one of the communication systems by replacing pipes, and initially it is not known what diameter the already installed ones have.
There are several ways to determine the diameter, but we will list only the simplest ones:
After receiving the outer diameter, you can find out the inner one. Only for this you need to know the thickness of the walls (if there is a cut, just measure with a tape measure or other device with a millimeter scale).
Assume that the wall thickness is 1 mm. This figure is multiplied by 2 (if the thickness is 3 mm, then it is also multiplied by 2 in any case) and subtracted from the outer diameter (18.85- (2 x 1 mm) = 16.85 mm).
It's great if you have a caliper at home. The pipe is simply wrapped around the measuring teeth. We look at the desired value on a double scale.
Arm yourself with a tape measure or measuring tape (women measure their waist like this). Wrap it around the pipe and record the measurement. Now, to obtain the desired characteristic, it is enough to divide the resulting figure by 3.1415 - this is the Pi number.
Example:
Imagine that in girth (circumference L) your pipe 59.2 mm. L=ΠD, resp. diameter will be: 59.2 / 3.1415= 18.85mm.
Types of steel pipes according to their production method
Electrowelded (straight-seam)
For their manufacture, strips or sheet steel are used, which are bent to the desired diameter on special equipment, and then the ends are connected by welding.
The impact of electric welding guarantees a minimum joint width, which makes it possible to use them for the construction of gas pipelines or water pipelines. The metal in most cases is carbon or low-alloy.
Indicators finished products regulated by the following documents: GOST 10704-91, GOST 10705-80 GOST 10706-76.
At the same time, please note that a pipe made in accordance with standard 10706-26 is distinguished by maximum strength among its own kind - after creating the first connecting seam, it is reinforced with four additional ones (2 inside and 2 outside).
The regulatory documentation indicates the diameters of products manufactured by electric welding. Their size is from 10 to 1420 mm.
Spiral-seam
The material for production is steel in rolls. Products are also characterized by the presence of a seam, but unlike the previous production method, it is wider, which means that the ability to withstand high internal pressure is lower. Therefore, they are not used for the construction of gas pipeline systems.
A specific type of pipe is regulated by GOST under the number 8696-74 .
Seamless
The production of a particular type involves the deformation of specially prepared steel blanks. The deformation process can be carried out both under the influence high temperatures, and in a cold way (GOST 8732-78, 8731-74 and GOST 8734-75, respectively).
The absence of a seam has a positive effect on the strength characteristics - the internal pressure is evenly distributed over the walls (there are no "weak" places).
As for the diameters, the standards control their manufacture with a value of up to 250 mm. When buying products with sizes exceeding those indicated, you have to rely only on the integrity of the manufacturer.
It's important to know!
If you want to buy the most durable material, buy cold-formed seamless pipes. The absence of temperature effects has a positive effect on the preservation of the original characteristics of the metal.
Also, if an important indicator is the ability to withstand internal pressure, then choose round products. Profile pipes cope better with mechanical loads (they are well made metal frames etc.).
Here are a couple more great slides of creative advertising for a pipe manufacturer:
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.
main parameters
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:
- outer diameter, measured between the upper points of the threaded ridges located on opposite sides of the pipe;
- internal diameter as a value characterizing the distance from one lowest point of the cavity between the threaded ridges to another, also located on opposite sides of the pipe.
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.
Table of sizes of inch and metric threads
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
Differences from metric thread
By their own outward signs and characteristics, metric and inch threads do not have many differences, the most significant of which include:
- threaded comb profile shape;
- the procedure for calculating the diameter and pitch.
When comparing the shapes of threaded ridges, you can see that in inch threads such elements are sharper than in metric ones. If speak about exact dimensions, then the angle at the top of the crest of the 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:
- As the simplest template, a coupling or fitting is used, parameters internal thread which exactly correspond to the requirements given by GOST.
- The bolt, the parameters of the external thread of which must be measured, is screwed into a coupling or fitting.
- In the event that the bolt has formed a tight threaded connection with a coupling or fitting, then the diameter and pitch of the thread that is applied to its surface exactly correspond to the parameters of the template used.
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.
Slicing technologies
Cylindrical pipe thread, which belongs to the inch type (both internal and external), can be cut manually or mechanically.
Thread cutting by handThreading with a hand tool, which is a tap (for internal) or a die (for external), is performed in several steps.
- The pipe being processed is clamped in a vice, and the tool used is fixed in a wrench (tap) or in a die holder (die).
- The die is put on the end of the pipe, and the tap is inserted into inner part last.
- The tool used is screwed into the pipe or screwed onto its end by rotating the knob or die holder.
- To make the result cleaner and more accurate, you can repeat the cutting procedure several times.
Thread cutting on a lathe
Mechanically, pipe threads are cut according to the following algorithm:
- The pipe being processed is clamped in the machine chuck, on the support of which the thread-cutting tool is fixed.
- At the end of the pipe, using a cutter, they chamfer, after which they adjust the speed of movement of the caliper.
- After bringing the cutter to the surface of the pipe on the machine, the threaded feed is turned on.
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.
Accuracy classes and marking rules
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.
| 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
|
External diameter of the pipe to be connected |
SAE thread rating |
Thread rating UNF |
Thread outer diameter, mm |
Average thread diameter, mm |
thread pitch |
||
|
mm |
inch |
mm |
thread/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
| Conductor cross section, 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 | middle d | inner 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 | middle d | inner 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 | Converting pressure units |
|---|---|
| 1 J = 0.24 cal | 1 Pa = 1 N/m*m |
| 1 kJ = 0.28 W*h | 1 Pa \u003d 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 |
Inch to metric conversion tables. Thread size: table of metric and inch threads
The process of selecting the required cross-sectional dimensions of threads, cables and pipes is often time consuming. In addition to choosing suitable sizes, taking into account the parameters of the equipment, the customer has to independently convert the data into suitable units of measurement. This process is costly in terms of time.
We simplify this task, as we suggest you 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 conductors of wires and cables. Also, you can use the inch to metric conversion table, thereby accurately calculate the required cross-sectional dimensions.
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 the optimal sizes of wire cross-sections and pipe diameters.
We value the time of our customers, providing everyone with the opportunity to use ready-made solutions. In our tables translated standard sizes from inches to millimeters.
On this page you will also find translations of the main energy units and pressure units, therefore, you will be able to choose the right refrigeration equipment, taking into account the individual conditions of placement and operating modes of the units.
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 accounted for 14 strands;
- within 1 - 6 inches, the pitch is reduced to 2.309, forming 11 threads that do not affect the decrease or increase in 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). 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).
The 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 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.
Replacing steel pipes with polymer ones
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 1" pipe cross-section, 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 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 digital values. sections are 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, using the 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 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.
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?
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:
- 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).
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:
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.
- Rated value (Dn Dn,).
- external size.
The metric calculation system allows classifying structures into small ones - 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 inch - 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:
- pipeline 1/2 inch - 2.04 - 2.07 cm;
- 3/4 inches - 2.59 - 2.62 cm;
- 7/8 inch - 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:
Pipe diameter PP
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.
- Small - 0.5; one; 1.5; 2; 2.5; 3.2; 4; five; 6.3 and 7.5 cm is used for heating systems, drains and water supply in private buildings. An internal cross section of 3.2 cm is most popular in multi-storey buildings.
- Medium - 8; nine; 10; eleven; 12.5; 16; twenty; 25 and 31.5 cm is used for arranging plumbing and sewer systems, allowing you to change cast iron products with similar external parameters. Internal dimensions of 8, 9 and 10 cm are ideal for chemical environments.
- Large - 40 cm or more is used for arranging cold water supply and ventilation systems.
Pipes are marked in inches and mm. When choosing structures for the plumbing and heating systems, 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.
PP pipes cost:
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