GB/T 7306.1-2000 PDF English
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| GB/T 7306.1-2000 | English | 70 |
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Pipe threads with 55 degree thread angle where pressure-tight joints are made on the threads. Part 1: Parallel internal and taper external threads
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| GB/T 7306-1987 | English | 279 |
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Pipe threads where pressure-tight joints are made on the threads
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GB/T 7306.1-2000: PDF in English (GBT 7306.1-2000) GB/T 7306.1-2000
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 21.040.30
J 04
eqv ISO 7-1:1994
Pipe threads with 55 degree thread angle where
pressure-tight joints are made on the threads -
Part 1: Parallel internal and taper external threads
ISSUED ON: JULY 24, 2000
IMPLEMENTED ON: DECEMBER 01, 2000
Issued by: State Bureau of Quality and Technical Supervision
Table of Contents
Foreword ... 3
ISO foreword ... 4
1 Scope ... 5
2 Reference ... 5
3 Definitions and codes ... 5
4 Design profile ... 6
5 Basic dimensions ... 8
6 Chamfer ... 8
7 Tolerances ... 9
8 Thread length ... 9
9 Designation ... 10
Pipe threads with 55 degree thread angle where
pressure-tight joints are made on the threads -
Part 1: Parallel internal and taper external threads
1 Scope
This Standard specifies profile, dimensions, tolerances and designation of
parallel internal and taper external threads with 55 degree thread angle where
pressure-tight joints are made on the threads.
This Standard applies to threaded connection of pipes, valves, fittings, cocks
and other pipeline accessories.
It is permissible to add an appropriate sealing medium to thread pairs, such as
apply tape, sealant on the thread surface, etc.
2 Reference
The following standards contain provisions which, through reference in this
Standard, constitute provisions of this Standard. At the time of publication, the
editions indicated are valid. All standards are subject to revision. The parties
who are using this Standard shall explore the possibility of using the latest
version of the following standards.
GB/T 14791-1993 The terms of screw threads (neq ISO 5408:1983)
3 Definitions and codes
3.1 Definitions
In addition to the following two terms, other terms of threads used in the
standard are in accordance with GB/T 14791.
3.1.1 reference plane
When the thread is inspected, visible surface that is referenced when reading
the inspection value (position deviation of the gauge plane). For internal threads
it is the outer end face, for external threads it is the small end face.
3.1.2 accommodation length
Axial distance from the outer end face of the internal thread to the first obstacle
that prevents the external thread from being screwed in.
3.2 Codes
D - major diameter of the internal thread at the gauge plane;
d - major diameter (gauge diameter) of the external thread at the gauge plane;
D2 - pitch diameter of the internal thread at the gauge plane;
d2 - pitch diameter of the external thread at the gauge plane;
D1 - minor diameter of the internal thread at the gauge plane;
d1 - minor diameter of the external thread at the gauge plane;
n - number of threads contained in an axial length of 25.4 mm;
P - pitch;
H - fundamental triangle height;
h - thread height;
r - radius of rounded crests and the roots;
T1 - tolerance on the gauge length (gauge plane position) of an external thread;
T2 - tolerance on the gauge plane position of an internal thread.
4 Design profile
4.1 The design profile of parallel internal threads shall comply with the
requirements of Figure 1. The flank angles of the left and right flanks are equal.
The relevant dimensions are calculated according to the following formula:
NOTE: The angle and the axial length of the chamfer of the outer end face of internal threads
will affect the inspection result of the taper thread plug gauge on parallel internal threads.
7 Tolerances
7.1 The limit deviation (±T1/2) of the gauge length of taper external threads shall
comply with the provisions of columns 9 and 10 of Table 1.
7.2 The limit deviation of each diameter of parallel internal threads shall comply
with the provisions of columns 18 and 19 of Table 1.
8 Thread length
8.1 The useful thread length of taper external threads shall not be less than the
sum of the actual value of the gauge length and the fitting allowance.
Corresponding to the three conditions of the maximum, basic and minimum
dimensions of the gauge length, columns 16, 15 and 17 of Table 1 respectively
give the minimum useful thread length required for the corresponding condition.
8.2 When the rear end of parallel internal threads does not adopt the retracting
structure, the minimum useful thread length shall be able to accommodate the
taper external thread having the length specified in column 16 of Table 1. When
the rear end of parallel internal threads adopts the retracting structure, the
accommodation length shall be able to accommodate the taper external thread
having the length specified in column 16 of Table 1, and the minimum useful
thread length shall not be less than 80 % of the length specified in column 17
of Table 1, see Figure 4.
......
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.
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