GB/T 7306.1-2000Pipe threads with 55 degree thread angle where pressure-tight joints are made on the threads. Part 1: Parallel internal and taper external threads (English PDF)

Foreword

International Standard ISO 7-1.1994 "Pipe threads where pressure-tight joints

are made on the threads - Part 1.Dimensions, tolerances and designation"

specifies two mating types of threads, namely. parallel internal threads and

taper external threads ("parallel/taper") and parallel internal threads and parallel

external threads ("taper/taper"). This Standard is equivalent to the technical

content of mating of parallel internal threads and taper external threads in ISO

7-1.1994.

This Standard replaces the technical content of mating of parallel internal

threads and taper external threads in GB/T 7306-1987 "Pipe threads where

pressure-tight joints are made on the threads".

Compared with GB/T 7306-1987, the main changes are as follows.

- DIVIDE the technical contents of "parallel/taper" and "taper/taper" mating

threads in the old standard INTO two new standards;

- In the new standard, the position of the gauge plane of the internal thread

is separated from its end face, and the gauge plane is located at half the

pitch within the end face;

- The new standard uses the thread feature codes R1 and R2 to clearly

distinguish the taper external threads used in the two mating types;

- SIMPLIFY the designation method for thread pairs.

This Standard replaces part of the content of GB/T 7306-1987 from the date of

implementation.

This Standard was proposed by National Machinery Industry Bureau.

This Standard is under the jurisdiction of National Technical Committee on

Threads of Standardization Administration of China.

Mechanical Science Research Institute of the Ministry of Machinery Industry is

responsible for the drafting of this Standard. Henan First Tools Factory, Jiangsu

Zhuqi Machinery Factory, Loctite (China) Co., Ltd., Xi'an Highway and

Transportation University participated in the drafting.

Main drafters of this Standard. Li Xiaobin, Zhao Jianmin, Zhang Jiansheng,

Tang Wei, Li Jiangsheng, Chai Zhixiang.

ISO foreword

ISO (the International Organization for Standardization) is a worldwide

federation of national standards bodies (ISO member bodies). The work of

preparing International Standards is normally carried out through ISO technical

committees. Each member body interested in a subject for which a technical

committee has been established has the right to be represented on that

committee. International organizations, governmental and non-governmental,

in liaison with ISO, also take part in the work.

ISO collaborates closely with the International Electrotechnical Commission

(IEC) on all matters of electrotechnical standardization.

Draft International Standards (DIS) adopted by the technical committees are

circulated to the member bodies for voting. Publication as an International

Standard requires approval by at least 75 % of the member bodies casting a

vote.

International Standard ISO 7-1 was prepared by Technical Committee ISO/TC5,

Ferrous metal pipes and metallic fittings. Subcommittee SC5, Threaded or plain

end butt-welding fittings, threads, gauging of threads.

This third edition cancels and replaces the second edition (ISO 7-1.1982),

which has been technically revised.

ISO 7 consists of the following parts, under the general title Pipe threads where

pressure-tight joints are made on the threads.

- Part 1.Dimensions, tolerances and designation

- Part 2.Verification by means of limit gauges

Annex A of Part 1 of ISO 7 is for information only.

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

4 Design profile

5 Basic dimensions

6 Chamfer

The axial length of the chamfer of the small end face of taper external threads

and the outer end face of parallel internal threads shall not exceed 1P.

7 Tolerances

8 Thread length

9 Designation