Pipe thread. Pipe Thread Sizes

Site arrangement 17.06.2019
Site arrangement

Parameters such as the quality of the pipe thread, its compliance with the axis of the pipe play a key role in the installation of plumbing and heating systems. In some cases, do-it-yourself cutting with a die is used. It must be said that this work difficult, inefficient and time consuming. It is better to cut with a cutter using a lathe.

General thread information

Pipe threads are protrusions and cavities with the same section, evenly spaced on a cylindrical or conical surface (for example, nuts, screws, bolts). They are located along a helix with the same pitch.

In everyday life, parts with a cylindrical thread are usually used. However, there are other types as well. There are two defining parameters for metric threads: pitch and diameter. An inch thread is so named because its defining characteristics are the diameter, expressed in inches or fractions of an inch. Also an important parameter in this case is the number of turns located on the length of an inch. The size in inches indicates the clearance in the element, while the outer diameter of the part is large.

Pipe thread table according to GOST

Important: One inch equals 2.54 cm. There is also another unit of measurement - a pipe inch. It is equal to 33, 249 mm. What is this inch unit of measurement? They brought it out like this: a value characterizing the thickness of both walls of the pipe was added to the value in inches.

There are two types of pipes, the parameter for the classification of which is the pipe inch:

  • Product with an outer diameter of 33, 249 mm;
  • Product with an outer diameter of 21.25 mm.

An inch thread is a set of parameters necessary for connecting pipes, fittings and other parts. From metric, among other things, it differs in such features as:

  • Pointed ridges-hollows;
  • Rounded hilltops.

Dimensions

AT living conditions most often you can find pipes with the following parameters and dimensions determined by GOST:

  • Thread 14 threads per 1 inch. In this case, the pitch is 1.814 mm. The diameter can be ½ or ¾;
  • 11 threads per 1 inch. In this case, the pitch is 2.309 mm. The diameter can be 1, 1 ¼, 1 1/2, 2.

Inch threads are made only on pipelines whose dimensions do not exceed 6″. If the parameters of the pipe are greater, it is mounted in the system by means of welding work. Its designations according to GOST: G (the value of the passage of elements, indicated in inches), A, B (the degree of accuracy of diameters).

The selection of inch threaded pipes requires knowledge of many parameters. For this purpose, there are a number of tables that list all the important values. There are tables from which you can find out the steps and their relationship with threads per inch. So you can quickly and easily get acquainted with all necessary information. You can find all the necessary tables on our website. They will help not only amateurs, but also professionals in working with pipes.

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 Options

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 ​​\u200b\u200bof external, medium and inner diameters threads, 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 - outside diameter internal thread(couplings); 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 pipe thread size 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 Options

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

MAIN PARAMETERS OF INCH THREADS
(standards BSW (Ww), BSF, UNC, UNF)

The tops and bottoms of the profile of an inch thread, similarly to a metric thread, are flat cut. The pitch of an inch thread is determined by the number of threads (turns) per 1 inch, but it has a 55° point angle (Whitworth thread - British BSW (Ww) and BSF), a 60° point angle (American UNC and UNF standard ).

The outside diameter of the thread is measured in inches 1" = 25.4 mm- dash (") symbol inches. An inch thread is characterized by the number of threads per inch. According to American standards, inch threads are made with coarse (UNC) and fine (UNF) pitch.
NPSM- American standard for inch cylindrical pipe threads.
NPT- American standard for inch conical threads.

Standards:

ASME/ANSI B1.1– 2003 Unified Inch Screw Threads, UN & UNR Thread Form
ASME/ANSI B1.10M– 2004 Unified Miniature Screw Threads
ASME/ANSI B1.15– 1995 Unified Inch Screw Threads, UNJ Thread Form

AMERICAN INCH THREAD

The main parameters of the inch thread:

d(D)- the outer diameter of the thread, respectively, of the bolt and nut;
dp (Dp)- the average thread diameter of the bolt and nut, respectively;
d i (D i)- the inner diameter of the thread, respectively, of the bolt and nut;
n is the number of threads per inch.

American Coarse Pitch Thread - UNS

Thread sizes, inches (mm)

D

Dp

D i

Thread sizes, inches (mm)

D

Dp

D i

№1 (1,8542)

№2 (2,1844)

1 (25,4)

№3 (2,5146)

1 1/8 (28,58)

№4 (2,8448)

1 1/4 (31,75)

№5 (3,1750)

1 3/8 (34,925)

№6 (3,5052)

1 1/2 (38,10)

№8 (4,1656)

1 3/4 (44,45)

№10 (4,8260)

№12 (5,4864)

2 (50,8)

2 1/4 (57,15)

1/4 (6,3500)

2 1/2 (63,5)

5/16 (7,9375)

2 3/4 (69,85)

3/8 (9,5250)

7/16 (11,1125)

3 (76,2)

1/2 (12,700)

3 1/4 (82,55)

9/16 (14,2875)

3 1/2 (88,9)

5/8 (15,8750)

3 3/4 (95,25)

3/4 (19,0500)

4 (101,6)

7/8 (22,2250)

American Fine Pitch Thread - UNF

Thread sizes, inches (mm)

D

Dp

D i

Thread sizes, inches (mm)

D

Dp

D i

№0 (1,524)

3/8 (9,525)

№1 (1,8542)

7/16 (11,1125)

№2 (2,1844)

1/2 (12,700)

№3 (2,5146)

9/16 (14,2875)

№4 (2,8448)

5/8 (15,875)

№5 (3,1750)

3/4 (19,050)

№6 (3,5052)

7/8 (22,225)

№8 (4,1656)

№10 (4,8260)

1 (25,4)

№12 (5,4864)

1 1/8 (28,58)

1 1/4 (31,75)

1/4 (6,350)

1 3/8 (34,925)

5/16 (7,9375)

1 1/2 (38,10)

American Extra Fine Pitch Thread - UNEF

Thread sizes, inches (mm)

D

Dp

D i

Thread sizes, inches (mm)

D

Dp

D i

№12 (5,4864)

1 (25,4)

1/4 (6,350)

1 1/16 (26,987)

5/16 (7,9375)

1 1/8 (28,58)

3/8 (9,525)

1 3/16 (30,162)

7/16 (11,1125)

1 1/4 (31,75)

1/2 (12,700)

1 5/16 (33,337)

9/16 (14,2875)

1 3/8 (34,925)

5/8 (15,875)

1 7/16 (36,512)

11/16 (17,462)

1 1/2 (38,10)

3/4 (19,050)

1 9/16 (39,687)

13/16 (20,637)

1 5/8 (41,27)

7/8 (22,225)

1 11/16 (42,86)

15/16 (23,812)

Thread sizes are the outside diameter of the thread expressed in fractional inch. One of the main characteristics of an inch screw thread is the number of threads per inch of thread length (n). The number of turns and the thread pitch P are related by:

American standards provide for two forms of thread:

Thread with a flat cavity, which is indicated by the letters UN;
- a thread with a radius cavity, which is indicated by the letters UNR.

The standard defines three classes of thread accuracy. These classes are designated as 1A, 2A, 3A, 1B, 2B, 3B. Accuracy classes 1A, 2A, 3A refer to external threads; accuracy classes 1B, 2B, 3B refer to internal threads. Accuracy class 1A, 1B is the coarsest and is used in cases where quick and easy assembly is required, even with partially dirty and dented threads. Accuracy class 2A, 2B is the most common and is used for general purpose threads. Accuracy class 3A, 3B imposes the most stringent requirements on threads and is used in cases where it is required to ensure a minimum clearance in a threaded connection.

Thread designation. Recorded first nominal size, then the number of threads per inch of thread, the thread group symbols, and the accuracy class symbol. The letters LH at the end of the entry indicate the left-hand thread. The nominal size is the outer diameter, defined as a fractional size or thread number, or their decimal equivalent.
For example: 1/4 - 20UNS - 2A or 0.250 - 20UNC - 2A

BRITISH STANDARD INCH THREADS
(BSW(Ww) and BSF)

Symbol carving B.S.P.
the size
in		 thread pitch largest diameter smallest diameter A/F
mm		 length
mm		 pipes tap hole diameter
(for drill) mm
in
(TPI)		 mm mm in mm in DN
mm		 OD
mm		 OD
in		 thickness
mm		 BSP.PL
(RP)		 BSP.F
(G)
-1 1 / 16 28 0,907 7,723 0,304 6,561 0,2583 4±0.9 6,60 6,80
-2 1 / 8 28 0,907 9,728 0,383 8,565 0,3372 15 4±0.9 6 10,2 0,40 2 8,60 8,80
-4 1 / 4 19 1,337 13,157 0,518 11,445 0,4506 19 6±1.3 8 13,5 0,53 2,3 11,50 11,80
-6 3 / 8 19 1,337 16,662 0,656 14,950 0,5886 22/23 6.4±1.3 10 17,2 0,68 2,3 15,00 15,25
-8 1 / 2 14 1,814 20,955 0,825 18,633 0,7336 27 8.2±1.8 15 21,3 0,84 2,6 18,75 19,00
-10 5 / 8 14 1,814 22,911 0,902 20,589 0,8106 16 2,6 - 21,00
-12 3 / 4 14 1,814 26,441 1,041 24,120 0,9496 32 9.5±1.8 20 26,9 1,06 2,6 24,25 24,50
-16 1 11 2,309 33,249 1,309 30,292 1,1926 43 10.4±2.3 25 33,7 1,33 3,2 30,40 30,75
-20 1 1 / 4 11 2,309 41,910 1,650 38,953 1,5336 53 12.7±2.3 32 42,4 1,67 3,2 39,00 39,50
-24 1 1 / 2 11 2,309 47,803 1,882 44,846 1,7656 57 12.7±2.3 40 48,3 1,90 3,2 45,00 45,00
-32 2 11 2,309 59,614 2,347 56,657 2,2306 70 15.9±2.3 50 60,3 2,37 3,6 56,75 57,00
-40 2 1 / 2 11 2,309 75,184 2,960 72,227 2,8436 17.5±3.5 65 76,1 3,00 3,6
-48 3 11 2,309 87,884 3,460 84,927 3,3436 20.6±3.5 80 88,9 3,50 4
-64 4 11 2,309 113,030 4,450 110,073 4,3336 25.5±3.5 100 114,3 4,50 4,5
-80 5 11 2,309 138,430 5,450 135,472 5,3335 28.6±3.5 125 139,7 5,50 5
-96 6 11 2,309 163,830 6,450 160,872 6,3335 28.6±3.5 150 165,1 6,50 5

Related Documents:

GOST 3469-91: Microscopes. Thread for lenses. Dimensions
GOST 4608-81: Metric thread. Interference landings
GOST 5359-77: Ocular thread for optical devices. Profile and dimensions
GOST 6042-83: Round Edison thread. Profiles, dimensions and limit dimensions
GOST 6111-52: Conical inch thread with a profile angle of 60 degrees
GOST 6211-81: Conical pipe thread
GOST 6357-81: Cylindrical pipe thread
GOST 8762-75: Round thread with a diameter of 40 mm for gas masks and calibers for it. Main dimensions
GOST 9000-81: Metric thread for diameters less than 1 mm. Tolerances
GOST 9484-81: Trapezoidal thread. Profiles
GOST 9562-81: Trapezoidal single thread. Tolerances
GOST 9909-81: Conical thread of valves and cylinders for gases
GOST 10177-82: Thrust thread. Profile and main dimensions
GOST 11708-82: Thread. Terms and Definitions
GOST 11709-81: Metric thread for plastic parts
GOST 13535-87: Reinforced thrust thread 45 degrees
GOST 13536-68: Round thread for sanitary fittings. Profile, basic dimensions, tolerances
GOST 16093-2004: Metric thread. Tolerances. Landings with clearance
GOST 16967-81: Metric thread for instrumentation. Diameters and steps
GOST 24737-81: Trapezoidal single thread. Main dimensions
GOST 24739-81: Multi-start trapezoidal thread
GOST 25096-82: Thrust thread. Tolerances
GOST 25229-82: Metric conical thread
GOST 28487-90: Tapered tool joint thread for drill string elements. Profile. Dimensions. Tolerances

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 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

We recommend reading