GB/T 7306.1-2000 in English

《GB/T 7306.1-200055°密封管螺纹 第1部分:圆柱内螺纹与圆锥外螺纹》由TC108（全国螺纹标准化技术委员会）归口，主管部门为国家标准化管理委员会。
本标准规定了牙型角为55°、螺纹副本身具有密封性的圆柱内螺纹和圆锥外螺纹的牙型、尺寸、公差和标记。本标准适用于管子、阀门、管接头、旋塞及其他管路附件的螺纹联结。

1 Scope

This standard specifies the requirements for thread form, dimensions, tolerances and designation for parallel internal and taper external threads with 55° thread form angle for pairs on which pressure-tight joints are made.
This standard is applicable to the threaded jointing for pipes, valves, fittings, plugs and other pipeline equipment.
An appropriate jointing medium is allowed to be used on the thread pair, e.g. threaded surface wrapped in tape and coated with sealant.

2 Normative References

The following standards contain provisions which, through reference in this test, constitute provisions of this standard. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this standard are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below.
GB/T 14791-1993 The Terms of Screw Threads (neq ISO 5408:1983)

3 Definitions and Symbols

3.1 Definitions
All the thread terms used in this standard, other than the following two terms, comply with GB/T 14791.

Foreword i
ISO Foreword ii
1 Scope
2 Normative References
3 Definitions and Symbols
4 Thread Form Design
5 Basic Dimensions
6 Chamfers
7 Tolerances
8 Thread Lengths
9 Designation