The thread is inch. Inch pipe thread: general information 1 2 in. female thread

reservoirs 15.06.2019
reservoirs

Inch thread is used primarily to create pipe connections: it is applied both to the pipes themselves and to 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 settings

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 tops of the threaded ridges located on opposite sides pipes;
  • 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 important requirement will not be observed, 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 at 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 metric and various varieties 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- comb, caliber, 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, the parameters of the internal thread of which exactly correspond to the requirements given by GOST.
  • Bolt, parameters external thread to 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 hand

Threading with hand tool, which is used as a tap (for internal) or a die (for external), is performed in several steps.

  1. 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).
  2. The die is put on the end of the pipe, and the tap is inserted into the inside of the latter.
  3. The tool used is screwed into the pipe or screwed onto its end by rotating the knob or die holder.
  4. To make the result cleaner and more accurate, you can repeat the cutting procedure several times.

Thread cutting lathe

Mechanically, pipe threads are cut according to the following algorithm:

  1. The pipe being processed is clamped in the machine chuck, on the support of which the thread-cutting tool is fixed.
  2. At the end of the pipe, using a cutter, they chamfer, after which they adjust the speed of movement of the caliper.
  3. 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 a lathe only on tubular products whose thickness and rigidity allow this. Making pipe inch threads mechanically allows you to get a high-quality result, but the use of such technology requires the turner to have appropriate qualifications and the presence of 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.

Threaded fasteners have been known since antiquity. Scientists still find the remains of parts that look like modern screws and nuts. But carving was most widespread during the industrial revolution of the 18th century. Initially, the spread of a detachable threaded connection was hindered by the lack of standardization, which made it impossible to ensure the interchangeability of products. The talented English engineer Charles Whitworth solved this problem. He developed a unified system of sizes and designations, using the English inch for this. This is how the inch thread was born. And all sizes are listed in the table according to GOST.

Options

An inch thread is a detachable connection of a triangular profile, the angle of the vertices of which is 55 degrees. Its unit of measure is inches. It should be noted right away that in Russia the use of inch threads in the design of new products is prohibited. Its use is permitted only in the case of the manufacture of spare parts of equipment for which an inch thread has already been made. In addition, it is allowed to use this thread as a pipe connection and in the manufacture of sealing hydraulic elements.

Inch, like any other, is characterized by the following main parameters:

  • Outer diameter - the distance between the tops of the turns located on opposite sides of the thread. The larger the value of this parameter, the greater the axial load the thread can withstand. The reverse side of the coin is the deterioration of tightness associated with the accumulation of errors in threading.
  • Nominal (average) diameter - a circle inscribed in the thread profile, the diameter of which depends on the pitch, and occupies an intermediate position between the inner and outer diameters. This setting in normal conditions difficult to measure, and there is a reference table for threads to determine it.
  • Inner diameter - the diameter of a circle inscribed along the troughs of the thread profile.
  • Pitch - the distance between adjacent scallops of a threaded connection. This parameter is measured in the number of threads per inch. The pitch characterizes the value and distribution of stress between the turns of inch threads. Designers in their practice increase the pitch when large mechanical loads are applied to the thread. If the thread is subject to requirements for maintaining tightness, then the pitch is reduced.
  • Helix angle - the angle between the sides of the profile of the turns. Initially, its value for all types of inch threads was 55 degrees. But now more and more there are inch threads with a profile angle of 60 degrees.

Varieties of inch threads

There are many types of threaded connections, the dimensions of which are inches, but among them in Russia the following main types are distinguished:

  • Pipe cylindrical
  • Pipe conical

Each category has its own characteristics. Cylindrical pipe thread is regulated by GOST 6357-81. Thread sizes are standardized and listed in a special table. These inch threads are primarily characterized by a finer pitch, which means fewer threads per inch.

Table. Pipe cylindrical thread. GOST 6357-81.

Thread designation Number of steps z on a length of 25.4 mm Step P Thread diameter Profile working height H 1 Cornering radius R H H/6
1st row 2nd row outer d = D average d 2 \u003d D 2 internal d 1 = D 1
1/16"
1/8" 		- 28 0,907 7,723 7,142 6,561 0,580777 0,124557 0,871165 0,145194
9,728 9,147 8,566
1/4"
3/8" 		- 19 1,337 13,157 12,301 11,445 0,856117 0,183603 1,284176 0,214029
16,662 15,806 14,950
1/2"
5/8"		 14 1,814 20,955 19,793 18,631 1,161553 0,249115 1,742331 0,290389
22,911 21,749 20,587
26,441 25,279 24,117
30,201 29,039 27,877
1" 1 1/8"

1 3/4"

11 2,309 33,249 31,770 30,291 1,478515 0,317093 2,217774 0,369629
37,897 36,418 34,939
41,910 40,431 38,952
44,323 42,844 41,365
47,803 46,324 44,845
53,746 52,267 50,788
59,614 58,135 56,656
2 1/2"

3 1/2"

2 1/4"

3 3/4"

65,710 64,231 62,752
75,184 73,705 72,226
81,534 80,055 78,576
87,884 86,405 84,926
93,980 92,501 91,022
100,330 98,851 97.372
106,680 105,201 103,722
4" 4 1/2"

5 1/2"

113,030 111,551 110.072
125,730 124,251 122,772
138,430 136,951 135,472
151,130 149,651 148,172
163,830 162,351 160,872
When choosing thread sizes, the 1st row should be preferred to the 2nd.

Its second difference is a more rounded profile. It contributes to a tighter contact of the turns to each other, which reduces the likelihood of leakage when transporting fluid through this threaded connection.

Cylindrical pipe threading is performed on pipes whose diameter does not exceed 6 units of an inch. Pipes larger than this size require the use of high-precision equipment, which increases production costs. In this case, it is more efficient, both from a technological and financial point of view, to fix pipes by welding.

Pipe conical thread is represented by GOST 6211-81. Dimension table, tolerance limits and load values ​​are described in this standard. By the type of profile of the turns, the conical thread is similar to the inch thread, but it has 2 rather important differences.

Pipe taper thread. GOST 6211-81.

Thread size designation Step P Number of steps per length
25.4mm 		H H1 C R Thread diameters in the base plane Thread length
d=D d2 = D2 d1 = D1 l 1 l 2
1/16" 0,907 28 0,870935 0,580777 0,145079 0,124511 7,723 7,142 6,561 6,5 4,0
1/8" 9,728 9,147 8,566
1/4" 1,337 19 1,283837 0,856117 0,213860 0,183541 13,157 12,301 11,445 9,7 6,0
3/8" 16,662 15,806 14,950 10,1 6,4
1/2" 1,814 14 1,741870 1,161553 0,290158 0,249022 20,955 19,793 18,631 13,2 8,2
3/4" 26,441 25,279 24,117 14,5 9,5
1" 2,309 11 2,217187 1,478515 0,369336 0,316975 33,249 31,770 30,291 16,8 10,4
1 1/4" 41,910 40,431 38,952 19,1 12,7
1 1/2" 47,803 46,324 44,845
2" 59,614 58,135 56,656 23,4 15,9
2 1/2" 75,184 73,705 72,226 26,7 17,5
3" 87,884 86,405 84,926 29,8 20,6
3 1/2" 100,330 98,851 97,372 31,4 22,2
4" 113,030 111,551 110,072 35,8 25,4
5" 138,430 136,951 135,472 40,1 28,6
6" 163,830 162,351 160,872

First of all, it is that there are two types of profile angles: 55 and 60 degrees. The second difference is that the thread is cut along a cone, due to which the conical threads have such a quality as self-sealing (a table with taper values ​​\u200b\u200bis indicated in the reference literature). Therefore, fastenings with the help of them do not require the use of additional sealing elements: linen thread, yarn with red lead, etc.

Marking and accuracy classes

There are 3 thread accuracy classes: the first (the roughest), the second and the third (the most accurate). The choice of one or another class depends on 2 factors: the dimensions of the thread diameter taken from the table, the fluid pressure in the pipeline. The higher the thread class, the more fluid pressure it can withstand.

Dimensions are checked for compliance with a certain accuracy class using special gauges. This method allows you to most reliably determine the compliance of the thread with the required dimensions, but it is more laborious. This method is effective in the conditions of multi-batch production of parts that require the presence high precision. When the series is not so large and there are no increased requirements for accuracy, the dimensions of the threads are controlled as follows:

  • The dimensions of the outer diameter are measured using a caliper, micrometer and other mechanical measuring instruments. Then the readings are compared with the reference table.
  • Pitch sizes are determined by applying special combs, such as an inch thread gauge. Then the resulting number of threads per inch is correlated with the value of the inch thread size table. The easiest way to measure the thread pitch is to take a ruler, mark 25.4 millimeters on it and count how many turns are included in this segment. We note right away that this method is the most rough and is not suitable for measuring threads with the third and second accuracy classes.

Inch thread designation in technical documentation let's look at an example:

The letter "G" means that the pipe thread is cylindrical. Conical pipe according to Russian standards is denoted by the letter "K".

The number "2" indicates the size of the outer diameter. The unit of measure is inches. Thread sizes and their options are fully regulated by GOSTs and are listed in special tables.

The letters "LH" indicate that the thread has a left-hand screw direction. The absence of this designation indicates the right direction.

The number "2" characterizes the accuracy class. The table of deviation limits is indicated in GOST. The number "40" is a size that characterizes the screwing length.

Thread making

To obtain an inch cut, 2 main methods are used:

  • knurling;
  • Slicing.

Knurled ones are made using special thread-rolling rollers, the profile of which follows the contour of the thread. The workpiece is placed between the rollers, and the threads are rolled to the required dimensions.

Threads made by this method have higher mechanical characteristics due to a smoother distribution of stress waves between the turns. Also, knurling has a high productivity, which allowed it to find extensive use in mass production.

The disadvantage of the rolling method is the complexity of manufacturing rollers. Their accuracy should be high level. Otherwise, it is very difficult to guarantee the required thread sizes. The second point is the material of the commercials. It must have improved mechanical properties. Usually, high-alloy stamped steels are used for this. All this makes the knurling method very costly from a financial point of view.

Cut threads are easier to manufacture, but mechanical properties, especially in terms of endurance limit, are noticeably inferior to knurled ones. This is due to the presence of sharper profile edges and, accordingly, a higher value of the stress coefficient.

The product is cut in two ways:

  • Manually.
  • Using a lathe.

For manual cutting, a tap is used (for the inner river) and a die (for the outer). The pipe is clamped. One of the indicated types of improvised tools is put on and screwed onto its end, depending on the type of thread. Perform cutting. This process is repeated to improve purity and accuracy.

On a lathe, the algorithm of actions is quite similar. Only the pipes are clamped not in a vice, but in the chuck of the machine. Next, the cutter is brought in, the threaded feed is turned on and the machine begins the manufacturing process. This method is more efficient than manual cutting, but requires a certain qualification from the turner.

Pipe thread cylindrical, G (BSPP)

Pipe cylindrical thread used in cylindrical threaded connections, as well as in connections of an internal cylindrical thread with an external conical thread according to GOST 6211-81. based on carving BSW(English) British Standard Whitworth, common inch pipe threads, also known as Whitworth threads) and is compatible with B.S.P.(English) british standard pipe thread) and denoted BSPP.

  • GOST 6357-81. Basic norms of interchangeability. The thread is pipe cylindrical.
  • ISO R228
  • EN 10226
  • DIN 259
  • BS2779
  • JIS B 0202

Thread parameters

Inch thread with a profile angle at the top of 55 °, the theoretical profile height H = 0.960491P.

Cut into pipes up to size 6", pipes over 6" are welded.

Symbol according to GOST 6357-81: letter G, the numerical value of the nominal diameter of the pipe in inches , the accuracy class of the average diameter ( BUT, AT), and letters LH for left hand thread. For example, a thread with a nominal diameter of 1 1/8, accuracy class BUT- designated as: G 1 1/8-A.

According to GOST 6357-81 Cylindrical pipe thread. Basic standards of interchangeability There are four values ​​for the thread pitch of a cylindrical pipe.

Table 2. Cylindrical pipe thread size designation (G), pitches and nominal values ​​​​of the outer, middle and inner thread diameters, mm
Thread size designation P step Thread diameters
Row 1 Row 2 d=D d2=D2 d1=D1
1/16" 0,907 7,723 7,142 6,561
1/8" 9,728 9,147 8,566
1/4" 1,337 13,157 12,301 11,445
3/8" 16,662 15,806 14,950
1/2" 1,814 20,955 19,793 18,631
5/8" 22,911 21,749 20,587
3/4" 26,441 25,279 24,117
7/8" 30,201 29.0З9 27,877
1" 2,309 33,249 31,770 30,291
1⅛" 37,897 36,418 34,939
1¼" 41,910 40,431 38,952
1⅜" 44,323 42,844 41,365
1½" 47,803 46,324 44,845
1¾" 53,746 52,267 50,788
2" 59,614 58,135 56,656
2¼" 65,710 64,231
2½" 75,184 73,705 72,226
2¾" 81,534 80,055 78,576
3" 87,884 86,405 84,926
3¼" 93,980 92,501 91,022
3½" 100,330 98,851 97,372
3¾" 106,680 105,201 103,722
4" 113,030 111,551 110,072
4½" 125,730 124,251 122,772
5" 138,430 136,951 135,472
5½" 151,130 148,651 148,172
6" 163,830 162,351 160,872
where d is the outer diameter of the outer thread (pipe); D - outer diameter of the internal thread (coupling); D 1 - internal diameter of the internal thread; d 1 - inner diameter of the external thread; D 2 - the average diameter of the internal thread; d 2 - the average diameter of the external thread. When choosing a size pipe thread first row should be preferred second.

The designation of the thread size corresponds to the inner diameter of the pipe according to one of the standards (en: Nominal Pipe Size).

Conical pipe thread, R (BSPT)

Pipe conical thread used in conical threaded connections, as well as in connections with an external conical thread from an internal cylindrical thread according to GOST 6357-81. based on carving BSW(English) British Standard Whitworth) and thread compatible B.S.P.(English) british standard pipe tapered thread ), called BSPT(seal is achieved by crushing the thread at the place of the threaded connection when the fitting is screwed in).

  • GOST 6211-81. Basic norms of interchangeability. The thread is pipe conical.
  • ISO R7
  • DIN 2999
  • BS21
  • JIS B 0203

Thread parameters

Inch thread with taper 1:16 (taper angle φ=3°34’48"). Profile angle at apex 55°.

Symbol: letter R for external thread and Rc for internal thread (GOST 6211-81. Basic standards of interchangeability. Conical pipe thread.), numerical value of the nominal thread diameter in inches (inch), letters LH for left-hand thread. For example, a thread with a nominal diameter of 1 1/4 is designated as R 1 1/4.

Thread size designation, pitches and nominal values ​​of the outer, middle and inner diameters of the pipe conical thread (R), mm
Size designation
carving		 Step P Thread length
working Outer
d=D		 Average
d2=D2		 Interior
d1=D1
1/16" 0,907 6,5 4,0 7,723 7,142 6,561
1/8" 6,5 4,0 9,728 9,147 8,566
1/4" 1,337 9,7 6,0 13,157 12,301 11,445
3/8" 10,1 6,4 16,662 15,806 14,950
1/2" 1,814 13,2 8,2 20,955 19,793 18,631
3/4" 14,5 9,5 26,441 25,279 24,117
1" 2,309 16,8 10,4 33,249 31,770 30,291
1¼" 19,1 12,7 41,910 40,431 38,952
1½" 19,1 12,7 47,803 46,324 44,845
2" 23,4 15,9 59,614 58,135 56,565
2½" 26,7 17,5 75,184 73,705 72,226
3" 29,8 20,6 87,884 86,405 84,926
3½" 31,4 22,2 100,330 98,851 97,372
4" 35,8 25,4 113,030 111,551 110,072
5" 40,1 28,6 138,430 136,951 135,472
6" 40,1 28,6 163,830 162,351 160,872

Round thread for sanitary fittings, Kr

Round thread for sanitary fittings. The thread is used for spindles, valves, faucets, toilet and water taps.

Thread NPSM (National pipe thread)

Thread inch pipe cylindrical (eng. NPSM) - American thread standard according to ANSI /ASME B1.20.1. The standard provides thread sizes from 1/16" to 24" for ANSI/ASME B36.10M , BS 1600 , BS EN 10255 and ISO 65 pipe.

Thread size designation NP, pitches and nominal values ​​of outer, middle and inner thread diameters, mm
Size designation
carving		 Threads per inch Thread length Thread diameter in base plane
working From the end of the pipe to the main plane Outer
d=D		 Average
d2=D2		 Interior
d1=D1
1/16" 27 6,5 4,064 7,895 7,142 6,389
1/8" 7,0 4,572 10,272 9,519 8,766
1/4" 18 9,5 5,080 13,572 12,443 11,314
3/8" 10,5 6,096 17,055 15,926 14,797
1/2" 14 13,5 8,128 21,223 19,772 18,321
3/4" 14,0 8,611 26,568 25,117 23,666
1" 11½ 17,5 10,160 33,228 31,461 29,694
1¼" 18,0 10,668 41,985 40,218 38,451
1½" 18,5 10,668 48,054 46,287 44,520
2" 19,0 11,074 60,092 58,325 56,558
2½" 8 72,699
3" 88,608
3½" 101,316
4" 113,973
5" 141,300
6" 168,275
8" 219,075
10" 273,050
12" 323,850

Thread NPT (National pipe thread)

Thread inch conical pipe (eng. NPT) - American standard for threads with a taper of 1:16 (taper angle φ \u003d 3 ° 34’48 ") or cylindrical (eng. NPS) thread on ANSI/ASME B1.20.1. Thread NPT corresponds to GOST 6111-52. The thread is conical inch with a profile angle of 60 degrees. There is also an NPTF thread - sealing occurs due to thread crushing. The standard provides thread sizes from 1/16" to 24" for pipes according to standards ANSI/ASME B36.10M, BS 1600, BS EN 10255 and ISO 65.

The profile angle at the top is 60°, the theoretical profile height is Н=0.866025Р.

NPT thread size designation, pitches and nominal values ​​of outer, middle and inner thread diameters, mm
Size designation
carving		 Threads per inch Thread length Thread diameter in base plane
working From the end of the pipe to the main plane Outer
d=D		 Average
d2=D2		 Interior
d1=D1
1/16" 27 6,5 4,064 7,895 7,142 6,389
1/8" 7,0 4,572 10,272 9,519 8,766
1/4" 18 9,5 5,080 13,572 12,443 11,314
3/8" 10,5 6,096 17,055 15,926 14,797
1/2" 14 13,5 8,128 21,223 19,772 18,321
3/4" 14,0 8,611 26,568 25,117 23,666
1" 11½ 17,5 10,160 33,228 31,461 29,694
1¼" 18,0 10,668 41,985 40,218 38,451
1½" 18,5 10,668 48,054 46,287 44,520
2" 19,0 11,074 60,092 58,325 56,558
2½" 8 72,699
3" 88,608
3½" 101,316
4" 113,973
5" 141,300
6" 168,275
8" 219,075
10" 273,050
12" 323,850

Notes

see also

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
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

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


Size conversion tables: simple and fast

The process of selecting the required cross-sectional dimensions of threads, cables and pipes is often time consuming. In addition to the fact that it is necessary to choose the appropriate dimensions, 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 required dimensions sections.

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 optimal sizes cross-sections of wires 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 units of pressure, therefore, you will be able to choose the right refrigeration equipment, taking into account the individual conditions of placement and modes of operation of the units.

In this article, I want to not only give dry facts about the dimensions of an inch pipe thread with references to standards and GOSTs, but also bring to the reader an interesting fact about the features of the designation of the latter.

So, who has already encountered pipe threads more than once was surprised at the discrepancy between the outer diameter of the thread and its designation. For example, a 1/2 inch thread has an outer diameter of 20.95 mm, although logically with metric threads it should be 12.7 mm. The thing is that in inch threads they actually indicate the through hole of the pipe, and not the outer diameter of the thread. At the same time, adding the pipe wall to the size of the hole, we get an overestimated outer diameter, which we are used to in the designations of metric threads. Conventionally, the so-called pipe inch is 33.249 mm, that is, 25.4 + 3.92 + 3.92 (where 25.4 is the passage, 3.92 is the pipe wall). The pipe walls are taken based on the working pressure for the thread. Depending on the pipe diameter, they also increase accordingly, since a pipe with a larger diameter must have thicker walls than a pipe with a smaller dimater for the same working pressure.

Pipe threads are divided into the following:

Cylindrical pipe thread

This is an inch thread based on the BSW (British Standard Whitworth) thread and corresponds to the BSP (British standard pipe thread) thread, has four pitch values ​​of 28,19,14,11 threads per inch. It is cut on pipes up to size 6", pipes over 6" are welded.

The profile angle at the top is 55°, the theoretical profile height is Н=0.960491Р.

Standards:
GOST 6357-81: Basic norms of interchangeability.
The thread is pipe cylindrical. ISO R228, EN 10226, DIN 259, BS 2779, JIS B 0202.

Symbol: the letter G, the numerical value of the nominal diameter of the pipe in inches (inch), the accuracy class of the average diameter (A, B), and the letters LH for left-hand threads. For example, a thread with a nominal diameter of 1 1/4", accuracy class A - is designated as G1 1/4-A. Again, we recall that it should be borne in mind that the nominal thread size corresponds to the pipe clearance in inches. The outer diameter of the pipe is in some proportion with this size and more, respectively, by the thickness of the pipe walls.

Cylindrical pipe thread size designation (G), pitches and nominal values ​​of outer, middle and inner thread diameters, mm

Thread size designationP stepThread diameters
Row 1Row 2d=Dd2=D2d1=D1
1/16" 0,907 7,723 7,142 6,561
1/8" 9,728 9,147 8,566
1/4" 1,337 13,157 12,301 11,445
3/8" 16,662 15,806 14,950
1/2" 1,814 20,955 19,793 18,631
5/8" 22,911 21,749 20,587
3/4" 26,441 25,279 24,117
7/8" 30,201 29.0З9 27,877
1" 2,309 33,249 31,770 30,291
1⅛" 37,897 36,418 34,939
1¼" 41,910 40,431 38,952
1⅜" 44,323 42,844 41,365
1½" 47,803 46,324 44,845
1¾" 53,746 52,267 50,788
2" 59,614 58,135 56,656
2¼" 65,710 64,231 62,762
2½" 75,184 73,705 72,226
2¾" 81,534 80,055 78,576
3" 87,884 86,405 84,926
3¼" 93,980 92,501 91,022
3½" 100,330 98,851 97,372
3¾" 106,680 105,201 103,722
4" 113,030 111,551 110,072
4½" 125,730 124,251 122,772
5" 138,430 136,951 135,472
5½" 151,130 148,651 148,172
6" 163,830 162,351 160,872

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