Pipe cylindrical thread GOST 6357-81. Substantive provisions
GUEST 6357 from? 81 year extends its effect on the pipe thread, which is mainly used for joining fittings, pipes and fittings. Internal cylindrical and external conical threads can be connected, as well as its simply cylindrical shapes. The required dimensions are set in GOST, tolerances and profile parameters. The conical thread must meet the standard 6211.
Threads are often used to connect metal pipes, and it is necessary to cut it in strict accordance with GOST
Pipe thread profile
GUEST 6357- 81 the main parameters of the profile are regulated. The required dimensions in millimeters are given in the table.
Table 1
| step | The height of the output triangle | Number of steps in length 2,54 cm | Profile height (working), * 10-1 | Radius of rounding of a hollow and top of a carving, * 10-1 |
| 0,907 | 0,871165 | 28 | 5,80777 | 1,24557 |
| 1,337 | 1,284176 | 19 | 8,56117 | 1,83609 |
| 1,814 | 1,742331 | 14 | 11,61553 | 2,49115 |
| 2,309 | 2,217774 | 11 | 14,78515 | 3,17093 |
The value of the pitch of the tubular cylindrical thread (GUEST 6357) determined by the ratio 25,4 mm / number of steps. The result is rounded to the nearest thousandth and accepted as a starting point for calculating the basic parameters of the profile.
pay attention! The tops of external and internal threads with a flat cut are allowed, if the possibility of connection to the conical external thread on the document is excluded 6211.
Step is one of the defining parameters of pipe threading
Basic dimensions in millimeters, which are determined by GOST for pipe thread, are presented in the table 2. Symbols, respectively: a — 1/16, c — 1/4, e — 1/2, f — 3/4, g — 5/8 , h — 7/8, j — 1 1/4, d — 3/8, k — 1 1/8, m — 1 3/8, n — 1 3/4, l — 1 1/2, The - 2 1/2, q — 2 3/4, r — 3 1/4, s — 3 1/2, p — 2 1/4, t — 3 3/4, u - 4 1/2, v - 5 ?, b — 1/8.
Table 2
| Thread size | Step, * 10-1 | Thread diameter at, * 10 mm | |||
| I row | II row | equality external diameter external pipes and external diameter internal coupling |
equality secondary diameter internal and external carving |
equality inner diameter internal and external carving |
|
| a | 9,07 | 0,7723 | 0,7142 | 0,6561 | |
| b | 0,9728 | 0,9147 | 0,8566 | ||
| c | 13,37 | 1,3157 | 1,2301 | 1,1445 | |
| d | 1,6662 | 1,5806 | 1,4950 | ||
| e | 18,14 | 2,0955 | 1,9793 | 1,8631 | |
| f | g | 2,2911 | 2,1749 | 2,0587 | |
| 2,6441 | 2,5279 | 2,4117 | |||
| h | |||||
| 3,0201 | 2,9039 | 2,7877 | |||
| 1 | k | 23,09 | 3,3249 | 3,1770 | 3,0291 |
| 3,7897 | 3,6418 | 3,4939 | |||
| j | |||||
| 4,1910 | 4,0431 | 3,8952 | |||
| l | m | 4,4323 | 4,2844 | 4,1365 | |
| 4,7803 | 4,6324 | 4,4845 | |||
| n | |||||
| 5,3746 | 5,2267 | 5,0788 | |||
| 2 | p | 5,9614 | 5,8135 | 5,6656 | |
| 6,5710 | 6,4231 | 6,2752 | |||
| The | |||||
| 7,5184 | 7,3705 | 7,2226 | |||
| 3 | q | 8,1534 | 8,0055 | 7,8576 | |
| 8,7884 | 8,6405 | 8,4926 | |||
| r | |||||
| 9,3980 | 9,2501 | 9,1022 | |||
| s | t | 10,0330 | 9,8851 | 9,7372 | |
| 10,6680 | 10,5201 | 10,3722 | |||
| 4 | 11,3030 | 11,1551 | 11,0072 | ||
| 5 | u | 12,5730 | 12,4251 | 12,2772 | |
| 13,8430 | 13,6951 | 13,5472 | |||
| 6 | v | 15,1130 | 14,9651 | 14,8172 | |
| 16,3830 | 16,2351 | 16,0872 | |||
Tolerances and screwing length of inch pipe thread
GUEST 6357 sets tolerances (deviation), which may have an inch pipe thread. They are calculated from the nominal profile in the direction perpendicular to its axis.
The length of the screwing can be short, normal or long
Tolerances of threaded average diameter are characterized by division into two classes of accuracy: A and B. Appropriate values for inch pipe thread (GUEST 6357) given in the table (symbols as in the Table 1).
Table 3
| thread designation | Step, * 10 mm | Internal thread | external thread | ||||
| diameters | |||||||
| internal | average | average | external | ||||
| Tolerances, * 10 micron | |||||||
| For class A | For class B | For class A | For class B | ||||
| a | 0,0907 | 28,2 | 10,7 | 21,4 | 10,7 | 21,4 | 21,4 |
| b | |||||||
| c | 0,1337 | 44,5 | 12,5 | 25,0 | 12,5 | 25,0 | 25,0 |
| d | |||||||
| e — h | 0,1814 | 54,1 | 14,2 | 28,4 | 14,2 | 28,4 | 28,4 |
| 1, j - n, 2 | 0,2309 | 64,0 | 18,0 | 36,0 | 18,0 | 36,0 | 36,0 |
| 6, o - v, 5, 3,4 | 21,7 | 43,3 | 21,7 | 43,4 | 43,4 | ||
Numeric values for tolerances in the document 6357 (4) established empirically. Also in GOST the lengths of screwing are given, which are divided into 2 groups: long and normal. The corresponding values in millimeters are given in the table (symbols correspond to Table. 1).
Table 4
| thread designation | Step, * 10 | Normal screwing length | Long screwing length |
| a | 0,0907 | 4-12 | > 12 |
| b | |||
| c | 0,1337 | 5-16 | > 16 |
| d | |||
| e — h | 0,1814 | 7-22 | > 22 |
| 1, j, k, m | 0,2309 | 10-30 | > 30 |
| 2, l, n — q, 3 | 12-36 | > 36 | |
| 6, 4, r — v, 5 | 13-40 | > 40 |
The value of the length of screwing in GOST 6357 also determined empirically.
And for internal, and for external threads there are marginal deviations in parameters
Maximum deviations of the sizes according to GOST 6357-81
Pipe cylindrical thread is characterized by the following maximum deviations for the internal, as well as external threads, which are presented in the table (with symbols as in Table. 1).
Table 5
| thread designation | Step, * 10 mm | Internal thread | external thread | |||||||
| diameters | ||||||||||
| internal | average | average | external | |||||||
| Deviation, * 10 micron | ||||||||||
| Upper border | Upper border | lower limit | lower limit | |||||||
| For class A | For class B | For class A | For class B | |||||||
| a, b | 0,0907 | +28,2 | +10,7 | +21,4 | -10,7 | -21,4 | -21,4 | |||
| c, d | 0,1337 | +44,5 | +12,5 | +25,0 | -12,5 | -25,0 | -25,0 | |||
| e — h | 0,1814 | +54,1 | +14,2 | +28,4 | -14,2 | -28,4 | -28,4 | |||
| 1, j - n, 2 | 0,2309 | +64,0 | +18,0 | +36,0 | -18,0 | -36,0 | -36,0 | |||
| 6, o - v, 5, 3, 4
|
+21,7 | +43,4 | -21,7 | -43,4 | -43,4 | |||||
Some provisions of GOST 6211-81
Conical pipe thread according to GOST 6211 from? 81 year has a taper 1:16. In the document, as in the standard 6357 for cylindrical, her profile is given, tolerances and sizes.
pay attention! The conical pipe thread has dimensions, step and diameter (in the main plane) the same, as in the document 6357 from? 81 year.
The parameters of the conical thread are stipulated in the GOST document 6211
Its possible length with symbols of size as in Table. 1 is given in the table.
Table 6
| Thread size | Working length, * 102 mm | The length of the outer thread from the main plane to the end, * 10 mm |
| a | 0,065 | 0,40 |
| b | 0,065 | 0,40 |
| c | 0,097 | 0,60 |
| d | 0,101 | 0,64 |
| e | 0,132 | 0,82 |
| f | 0,145 | 0,95 |
| 1 | 0,168 | 1,04 |
| j | 0,191 | 1,27 |
| l | 0,191 | 1,59 |
| 2 | 0,234 | 1,75 |
| The | 0,267 | 2,06 |
| 3 | 0,298 | 2,06 |
| s | 0,314 | 2,22 |
| 4 | 0,358 | 2,54 |
| 5 | 0,401 | 2,86 |
| 6 | 0,401 | 2,86 |
Suppose you connect an external conical thread to a cylindrical internal one, having an accuracy class of A.
Denote tubular conical thread (GUEST 6211) letter R - for external, Rc - for internal, Rp - for the inner cylindrical. The left-hand thread is supplemented by the symbol LH.
GUEST 6211, and 6357, approved in? 81 year, determine the dimensional values for the pipe thread. Structurally, the documents are similar, however, the difference in forms affects the numerical values.
