GB/T 7307-2001Pipe threads with 55-degree thread angle where pressure-tight joints are not made on the threads (English PDF)

1.1994 are. this Standard does not recommend pressure-tight pipe thread pairs (G/R)

or pressure-tight pipe thread pairs (Rp/G) composed of pressure-tight threads or non-

pressure-tight threads. The relevant content in the ISO standard is set up for the

customary practices of individual European countries, and there is virtually no mixed

pairing of pressure-tight threads or non-pressure-tight threads in other countries.

Compared with GB/T 7307-1987, the main modifications of this standard are as follows.

- DELETE class D internal threads;

- SIMPLIFY the designation method of thread pairs.

From the date of implementation, this Standard replaces GB/T 7307-1987.

This Standard is proposed by State Machinery Industry Bureau.

This Standard is under the jurisdiction of National Technical Committee on Threads of

Standardization Administration of China.

Mechanical Science Research Institute is responsible for the drafting of This Standard,

Jiangsu Zhuze Machinery Plant participates in the drafting of this Standard.

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

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 228-1 was prepared by Technical Committee ISO/TC 5,

Ferrous metal pipes and metallic fittings, Subcommittee SC 5, Threaded or plain end

butt-welding fittings, threads, gauging of threads.

This third edition cancels and replaces the second edition (ISO 228-1.1982), which

has been technically revised.

ISO 228 consists of the following parts, under the general title Pipe threads where

pressure-tight joints are not 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 228 is for information only.

Pipe threads with 55 degree thread angle where

pressure-tight joints are not made on the threads

3.1 Definitions

The terms of screw threads in this Standard comply with the specifications of GB/T

14791.

3.2 Symbols

D - Major diameter of the internal thread;

r - Radius of rounded crests and roots of the thread.

5.1 The basic dimensions of threads' major diameter, pitch diameter and minor

diameter are calculated according to the following equations.

5.5 For the bottom diameter of internal and external threads, the tolerance class is not

specified.

5.6 Within the tolerance zone of the top diameter, the rounded crests are allowed to

be flattened.

5.7 The basic dimensions and the tolerances of cylindrical pipe threads shall comply

with the specifications of Table 1.

6.1 The designation of cylindrical pipe threads shall consist of the thread description

code, the dimension code and the tolerance class code.

6.2 For left-hand threads, the tolerance class code of external threads or the dimension

code of internal threads shall be followed by "LH".

......