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GB/T 21873-2025: Rubber seals - Joint rings for water supply, drainage and sewerage pipelines - Specification for materials
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Std ID	Version	USD	Buy	Deliver [PDF] in	Title (Description)
GB/T 21873-2025	English	439	Add to Cart	4 days [Need to translate]	Rubber seals - Joint rings for water supply, drainage and sewerage pipelines - Specification for materials
GB/T 21873-2008	English	299	Add to Cart	3 days [Need to translate]	Rubber seals -- Joint rings for water supply, drainage and sewerage pipelines -- Specification for materials

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GB/T 21873-2025: Rubber seals - Joint rings for water supply, drainage and sewerage pipelines - Specification for materials

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ICS 83.140.50;91.140.60;91.140.80 CCSG43 National Standards of the People's Republic of China Replaces GB/T 21873-2008 Rubber seals for water supply, drainage pipes and sewage pipe interfaces Sealing ring material specifications (ISO 4633.2023, MOD) Published on 2025-10-31 Implemented on May 1, 2026 State Administration for Market Regulation The State Administration for Standardization issued a statement.

Table of contents

Preface III 1.Scope 1 2 Normative References 1 3.Terms and Definitions 2 4.Classification 2 5 Requirements 3 5.1 General Rules 3 5.2 Impact on water quality 4 5.3 Resistance to microorganisms 4 5.4 Dimensional Tolerances 4 5.5 Defects and Imperfections 4 5.6 Hardness 4 5.7 Tensile strength and elongation at break 4 5.8 Compression permanent deformation in air 5 5.9 Accelerated aging in hot air 5 5.10 Compression stress relaxation 5 5.11 Volume change after water immersion 5 5.12 Ozone Resistance 5 5.13 Overlapping of the ends of pre-vulcanized rubber profiles 5

6 Optional Requirements

6.1 Optional Performance Requirements 6 6.2 -25℃ low temperature performance 6 6.3 Volume change after oil immersion 7 6.4 Lifespan Estimation 7 7.Sample and Test Temperature 7.1 Specimen Preparation 7.2 Test temperature 8 8.Quality Assurance 9.Storage 8. 10 Markings 8 11.Signs and Labels 8 Appendix A (Informative) Changes in structural numbering between this document and ISO 4633.2023 9 Appendix B (Normative) Determination of Joint Strength 11 B.1 Overview 11 B.2 Sample 11 B.3 Test Procedure 11 Appendix C (Informative) Explanation of the lifespan calculation in section 6.4 12 Appendix D (Informative) Quality Assurance 13 Appendix E (Informative) Storage Guidelines for Sealing Rings 14 Reference 15

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 replaces GB/T 21873-2008 "Rubber Seals - Material Specifications for Interface Sealing Rings for Water Supply, Drainage Pipes and Sewage Pipes". Compared with GB/T 21873-2008, the main technical changes in the "Standard" are as follows, apart from structural adjustments and editorial modifications. a) Supplementary information on hardness grades has been added (see Table 1); b) Added seal application types WA, WC, and WG (see Chapter 4); c) The specific requirements for "microbial resistance" have been changed (see 5.3,.2008 version 4.1.3); d) Added "Optional Performance Requirements" and "Life Calculation (LT Type)" to the "Optional Requirements" section (see 6.1, 6.4); e) Added information about "testing the life of the seal" to the seal marking label [see Chapter 11h]. This document is modified to adopt ISO 4633.2023 "Rubber seals - Specification for interface sealing rings for water supply, drainage and sewage pipes". Compared with ISO 4633.2023, this document has undergone many structural adjustments. A comparison table of the structural numbering changes between the two documents can be found here. Appendix A. The technical differences between this document and ISO 4633.2023, and the reasons therefor, are as follows. ---The normative reference HG/T 4301-2012 has been added, specifying the requirements for "microbial resistance," namely, "test methods and..." The requirement that "the material should comply with the relevant national standards" should be changed to "the anti-mildew performance of the material should comply with Table 2, 9.3 of HG/T 4301-2012". The requirements for mildew resistance level not exceeding Grade 1 and the requirements of other relevant national standards (see 5.3) should be met to adapt to my country's technical conditions; ---ISO 3302-1 (see 5.4) has been replaced with the normatively referenced GB/T 3672.1 to adapt to my country's technical conditions; ---ISO 7743 has been replaced with normative reference GB/T 7757, and the references have been changed to normative references (see 5.5) to suit [the requirements]. Based on my country's technological conditions; ---ISO 9691.1992 (see 5.5) has been replaced with the normatively referenced GB/T 17604-1998 to adapt to my country's technical conditions; ---ISO 48-2 (see 5.6) has been replaced with the normatively referenced GB/T 6031 to adapt to my country's technical conditions; ---ISO 37 (see 5.7) has been replaced with the normatively referenced GB/T 528 to adapt to my country's technical conditions; ---ISO 2285.2019 has been replaced with GB/T 42279-2022, which is a normative reference, and the reference reference has been changed to a normative reference. (See 5.8.2) to adapt to my country's technological conditions; ---ISO 815-1.2019 (see 5.8.2, 6.4.3) has been replaced with the normatively referenced GB/T 7759.1-2015 to adapt to my country's national standards. Technical conditions; ---ISO 815-2 has been replaced with the normatively referenced GB/T 7759.2 (see 5.8.3 and Table 4) to adapt to my country's technical conditions; ---ISO 188.2023 (see 5.9) has been replaced with the normatively referenced GB/T 3512-2014 to adapt to my country's technical conditions; ---ISO 6914.2021 has been replaced with GB/T 9871-2008, which is a normative reference, and the reference references have been changed to normative references. (See 5.10) to adapt to my country's technological conditions; ---ISO 3384-1.2019 (see 5.10, 6.4.2) has been replaced with the normatively referenced GB/T 1685-2008 to adapt to my country's technical standards. Technical conditions; ---ISO 1431-1 (see 5.12) has been replaced with the normatively referenced GB/T 7762 to adapt to my country's technical conditions; ---A footnote has been added to the table, stating that "the hardness change value under the condition of -25℃ and 168h can be replaced by ShoreA after consultation with the customer." (See Table 4) to adapt to my country's technological conditions; ---ISO 3387 has been replaced with the normatively referenced GB/T 12832 (see 6.2 and Table 4) to adapt to my country's technical conditions; ---ISO 1817 has been replaced with the normatively referenced GB/T 1690 (see 6.3 and Table 4) to adapt to my country's technical conditions; ---ISO 11346 has been replaced with the normatively referenced GB/T 20028 (see 6.4 and Table 4) to adapt to my country's technical conditions; ---ISO 23529 (see 7.1) has been replaced with the normatively referenced GB/T 2941 to adapt to my country's technical conditions. The following editorial changes have been made to this document. ---Ozone concentration has been changed from "pphm" to "10⁻⁸", and the note has been deleted (see 5.12); ---The test rate for the strength of the sealing ring or the joint of the sample is changed from "(8.3±0.8)mm/s" to "(500±50)mm/min" (see B.3). Please note that some content in this document may involve patents. The issuing organization of this document assumes no responsibility for identifying patents. This document was proposed by the China Petroleum and Chemical Industry Federation. This document is under the jurisdiction of the National Technical Committee on Standardization of Rubber and Rubber Products (SAC/TC35). The main drafting units of this document are. Ma'anshan Hongli Rubber Products Co., Ltd., Xinxing Ductile Iron Pipes Co., Ltd., and Tianjin Jihua Rubber Products Co., Ltd. Product Co., Ltd., Jihua Rubber Industry Co., Ltd., Sichuan Daohong New Material Co., Ltd., Northwest Rubber & Plastics Research and Design Institute Co., Ltd. Company, Guoming Cast Pipe Co., Ltd., Shandong Guoming Water Conveying Fittings & Rubber Products Co., Ltd., Anhui Lujiang Huayi Rubber Products Co., Ltd. Company, Hebei Youlian Rubber Products Co., Ltd., Tieling Wuxing Sealing Research Institute Co., Ltd., Rifeng Enterprise (Foshan) Co., Ltd., Sichuan Jiasite Rubber Co., Ltd., Lianyungang Zhongfu Lianzhong Composite Materials Group Co., Ltd., Zhenjiang Shuanglong Sealing Materials Co., Ltd., Hubei Feige Technology Co., Ltd. Technology Co., Ltd., Hebei Huagen Technology Co., Ltd., Xingtai Rubber Factory, Xiamen Maifeng Sealing Parts Co., Ltd., Shanghai Yitong Technology Co., Ltd. Limited Liability Company, Hebei Quannai Rubber & Plastic Products Co., Ltd., Liaoning Honghai Xinxin Sealing Technology Co., Ltd., and Yuyao Zhenda Plastics Co., Ltd. The main drafters of this document are. Gao Shangjun, Shu Benqin, Wang Enqing, Qu Xiangjiang, Zhou Jiangfan, Zhou Wugang, Wei Hao, Wang Hao, Zhao Yingxin, and Ge Hongbing. Han Ping, Shi Zheng, Lin Xiyong, Yan Lin, Xu Huaming, Wei Wei, Wang Fei, Li Yang, Jin Jianguo, Zheng Huaan, Jiang Zhouming, Ma Liwen, Sun Bo, Gan Naicong, Huang Lianggen Wang Ying, Chen Yong, Xu Xiaohui, Liu Changsen, Li Hui, Ge Zifan, Li Zhiyou, Yin Wenhua, Li Chao, Zhang Fang, Liu Yuke, Li Jinjie, Ge Haijian Guo Junsheng. This document was first published in.2008, and this is its first revision. Rubber seals for water supply, drainage pipes and sewage pipe interfaces Sealing ring material specifications Warning. Users of this document must be familiar with standard laboratory procedures. This document is not intended to address all safety concerns associated with its use. All issues (if any). Users are responsible for taking appropriate safety and health precautions.

1 Scope

This document specifies the material requirements for vulcanized rubber seals used in the following pipelines. a) Cold drinking water (below 50℃) supply pipelines; b) Drainage, sewage and rainwater pipes (continuous flowing water not exceeding 45°C and intermittent flowing water not exceeding 95°C). The markings for various sealing rings specified in this document are determined based on the type, application, and requirements of the sealing ring. This document also specifies the general requirements for finished sealing rings. The performance of pipe joints is related to the properties of the sealing ring material and the geometry of the sealing ring. Regarding the design of the form and interface, relevant product standards also specify additional requirements for specific application scenarios. This document is intended to address these requirements where appropriate. Use with product standards that specify interface performance requirements. This document applies to cast iron pipes, steel pipes, ceramic pipes, cement pipes, reinforced concrete pipes, plastic pipes, and glass fiber reinforced plastic pipes. Sealing rings for all pipe interfaces, including material pipes. This document applies to the elastomeric portion of composite or non-composite rubber seals. It is applicable to materials with a hardness of 76 IRDH~95. Composite sealing rings between IRHDs are only suitable when the rubber directly participates in the sealing or when long-term sealing stability is required. Tensile elongation at break and compression permanent rate are also important considerations. Deformation and stress relaxation requirements. This document also applies to interface seals that use closed-cell foamed rubber material as part of the sealing ring.

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 528 Determination of tensile stress-strain properties of vulcanized rubber or thermoplastic rubber (GB/T 528-2009, ISO 37. 2005, IDT) GB/T 1685-2008 Determination of compressive stress relaxation in vulcanized or thermoplastic rubber at room temperature and high temperature (ISO 3384. 2005, MOD) GB/T 1690 Test methods for resistance to liquids of vulcanized or thermoplastic rubber (GB/T 1690-2010, ISO 1817.2005) MOD) GB/T 2941 General procedures for specimen preparation and conditioning in physical testing of rubber (GB/T 2941-2025, ISO 23529. 2016, IDT) GB/T 3512-2014 Accelerated aging and heat resistance test of vulcanized rubber or thermoplastic rubber in hot air (ISO 188.2011, IDT) GB/T 3672.1 Tolerances for rubber products – Part 1.Dimensional tolerances (GB/T 3672.1-2025, ISO 3302-1. 2014, IDT) ...