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GB/T 20671.4-2026Classification system and test methods for nonmetallic gasket materials — Part 4: Test method for sealability of gasket materials (English PDF)

非金属垫片材料分类体系及试验方法　第4部分：垫片材料密封性试验方法

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Issued by

SAMR; SAC

Level / Type

National · Recommended

Issue date

July 30, 2026

Implementation date

February 1, 2027

Scope

GB/T 20671.4-2026 is the English-translated version of 非金属垫片材料分类体系及试验方法　第4部分：垫片材料密封性试验方法.

GB/T 20671.4-2026 is the Chinese standard "Classification system and test methods for nonmetallic gasket materials — Part 4: Test method for sealability of gasket materials".

Its scope clause reads: This document provides an overview of the method for determining the sealing performance of non-metallic gasket materials at room temperature, including test equipment, test samples, and equipment debugging.

Sample preparation, equipment calibration, test procedures, result calculation, and test report. This document applies to determining the sealing performance of non-metallic gasket materials under different loads.

Test Method A is applicable to liquid leakage rate measurement. Test method B is applicable to the measurement of leakage rates for both liquid and gaseous media. Its clauses include terms and definitions; method overview; test equipment.

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Document preview — GB/T 20671.4-2026

National Standard of the People's Republic of China

ICS: 23.100.60
Classification: Q 61
Replacing: GB/T 20671.4-2006

Issued by: State Administration for Market Regulation; Standardization Administration of the PRC

Foreword
1 Scope
2 Edition and transition
3 Classification and status
4 Structure of the document
5 The English edition

1 Scope

This document provides an overview of the method for determining the sealing performance of non-metallic gasket materials at room temperature, including test equipment, test samples, and equipment debugging.

Sample preparation, equipment calibration, test procedures, result calculation, and test report.

This document applies to determining the sealing performance of non-metallic gasket materials under different loads. Test Method A is applicable to liquid leakage rate measurement.

Test method B is applicable to the measurement of leakage rates for both liquid and gaseous media.

2 Normative references

The contents of the following documents, through normative references within the text, constitute essential provisions of this document. Dated citations are listed below.

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 20671.1-2020 Classification System and Test Methods for Non-metallic Gasket Materials Part 1.Classification System for Non-metallic Gasket Materials

GB/T 20671.3-2020 Classification System and Test Methods for Non-metallic Gasket Materials Part 3.Test Methods for Liquid Resistance of Gasket Materials

3 Terms and Definitions

This document does not contain any terms or definitions that need to be defined.

4 Method Overview

4.1

The specimen is placed in the middle of the rigid flange. After applying the specified load to the flange, the test medium is introduced into the middle of the annular gasket and the specified pressure is reached.

For liquid sealing performance tests (Test Methods A and B), it is recommended to use the test liquid specified in Appendix A of GB/T 20671.3-2020.

The leakage rate is measured by the change in the horizontal level of the liquid inside a graduated glass tube fixed in a sealing performance testing device. (Gas Seal)

The performance test (Test Method B) uses nitrogen as the medium, and its leakage rate is measured by the change in the horizontal plane of the pressure gauge in the sealing performance test equipment.

The schematic diagram of the test apparatus for test method A is shown in Figure 1.

4.2

The results of the sealing performance test are expressed as the leakage rate, which is the volume (mL) of leakage per hour of the sample under the specified test conditions.

5 Test Equipment

5.1

Test Method A

5.1.1 Compressed air source and regulator

Provide compressed air and control the pressure between 0 kPa and 101.4 kPa using a suitable regulator.

5.1.2 Pressure measuring device

a pressure gauge or pressure meter with a pressure reading of 101.4 kPa and an accuracy of 0.5 kPa.

......
This preview omits tables, figures, formulas and parts of the technical clauses. The complete document — 15 pages — is available in the English PDF.

Referenced standards

Cited by

Editions of GB/T 20671.4

Edition	Title	Revision	Status
GB/T 20671.4-2026	Classification system and test methods for nonmetallic gasket materials — Part 4: Test method for sealability of gasket materials	current edition	Current
GB/T 20671.4-2006	Classification system and test methods for nonmetallic gasket materials — Part 4: Test method for sealability of gasket materials	previous edition	In force until 1 February 2027

This page sells the current edition, GB/T 20671.4-2026. Earlier editions are listed for reference only.

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