GB/T 18052-2025Methods of gauging and inspection of casing, tubing and line pipe threads (English PDF)

Foreword

This document complies with the provisions of GB/T 1.1-2020 "Standardization Work Guidelines Part

1.Structure and Drafting Rules of Standardization Documents". Drafting. This document supersedes GB/T 18052-2000 "Measurement and Inspection Methods for Casing, Tubing and Line Pipe Threads", and is consistent with GB/T 18052- Compared to.2000, aside from structural adjustments and editorial changes, the main technical changes are as follows:

a) The scope has been revised, and inspection methods for special threads on tubing and casing have been added (see Chapter 1, Chapter 1 of the.2000 edition);

b) Added terms and definitions such as "special thread," "ovalness," "sealing surface," "thread thickness," and "burr" (see 3.1);

c) The terms and definitions such as "internal thread," "external thread," "thread root," "thread crest," and "lead" have been deleted (see section

3.1 of the.2000 edition);

d) The terms and definitions for thread crest height, incomplete thread, and thread angle have been changed (see 3.1,.2000 edition 3.1);

e) Symbols such as A, L4, and P1 have been added (see 3.2);

f) Added abbreviations such as OM, PTL, and VTI (see 3.3);

g) The direct-connection thread (integral connection) has been removed (see

4.4 in the.2000 edition);

h) Increased requirements for inspection personnel (see Chapter 5);

i) The criteria for rejection due to incomplete 360° circumferential chamfering have been changed (see 7.4.4.1,

5.2.8.1 of the.2000 version);

1 Scope

GB/T 18052-2025 is the Chinese national standard covering measuring an oilfield tubular thread - the standoff against the gauge, the lead, taper and thread height, the instruments and their calibration, and the acceptance, on a joint that has to seal against gas pressure thousands of metres down. At 42,000 words. It replaces GB/T 18052-2000, a standard twenty-five years old. In force from 1 May 2026. Issued on 5 October 2025, it has been in force since 1 May 2026, replacing GB/T 18052-2000.

This document describes the appearance and dimensions of round threaded sleeves and tubing, trapezoidal threaded sleeves, special threaded sleeves and tubing, and line pipe threads. Methods for measuring and inspecting individual parameters such as inch, tightness, and thread. This document applies to the measurement and inspection of casing, tubing, and pipeline threads.

2 Normative references

The contents of the following documents, through normative references within the text, constitute essential provisions of this document. Dated citations are not included. For references to documents, only the version corresponding to that date applies to this document; for undated references, the latest version (including all amendments) applies. This document.

GB/T 9253 Machining, Measurement and Inspection of Casing, Tubing and Line Threads in the Oil and Gas Industry

GB/T 14791 Thread Terminology

JJF1063 Oil Thread Single Parameter Checker

JJF1108 Calibration Specification for Petroleum Thread Working Gauges SY/T 6445 Terminology for Common Defects in Oil Pipes

3 Terms, definitions, symbols and abbreviations

3.1 Terms and Definitions The following terms and definitions apply to this document.

3.1.1 tooth top height addendum The radial distance between the crest of a threaded tooth and its mid-diameter. [Source: GB/T 14791-2013, 4.15]

3.1.2 tooth height of thread The radial distance between the crest and the root of a threaded tooth. [Source: GB/T 14791-2013, 4.14]

3.1.3 Thread profile The thread profile shape over a pitch length in the axial plane.

3.1.4 black-crested threads Incomplete threads are formed due to the original rolled surface not being removed. [Source: GB/T 9253-2022, 3.1.4]