GB 5135.11-2025Automatic sprinkler systems - Part 11: Grooved pipe couplings and fittings (English PDF)

Foreword

GB 5135.11-2025 was issued on 31 October 2025 by the State Administration for Market Regulation and the Standardization Administration of the People's Republic of China, and comes into force on 1 November 2026. It carries no /T in its designation: it is a mandatory national standard.

This document was drafted in accordance with the rules given in GB/T 1.1-2020 Directives for standardization - Part 1: Rules for the structure and drafting of standardizing documents.

This document is Part 11 of GB 5135 Automatic sprinkler systems. The following parts of GB 5135 have been published: Part 1: Sprinklers; Part 2: Wet alarm valves, retarding chambers and water motor alarms; Part 3: Water spray nozzles; Part 4: Dry pipe valves; Part 5: Deluge valves; Part 6: General valves; Part 7: Water flow indicators; Part 8: Accelerators; Part 9: Early suppression fast response (ESFR) sprinklers; Part 10: Pressure switches; Part 11: Grooved pipe couplings and fittings; Part 13: Water curtain nozzles; Part 14: Pre-action installations; Part 15: Residential sprinklers; Part 16: Flexible sprinkler hoses; Part 17: Pressure reducing valves; Part 18: Pipe hangers and supports for fire protection; Part 19: Plastic pipes and fittings; Part 20: Coated steel pipes; Part 21: End test water installations; Part 22: Specific application sprinklers.

This document replaces GB 5135.11-2006 Automatic sprinkler systems - Part 11: Grooved pipe couplings and fittings. Compared with GB 5135.11-2006, apart from structural adjustments and editorial changes, the main technical changes are as follows: a) the requirements for appearance have been changed (see 5.1.1; 6.1.1 of the 2006 edition); b) the requirements for nominal diameter and groove dimensions have been changed (see 5.2.2 and 5.2.3; 6.1.3 and 6.2.2 of the 2006 edition); c) requirements for characteristic parameters, flange dimensions and thread dimensions have been added (see 5.2.5 to 5.2.7); d) the requirements for housing materials have been changed (see 5.3; 6.3 of the 2006 edition); e) the requirements for fasteners have been changed (see 5.4; 6.4 of the 2006 edition); f) the requirements for some performance parameters of the rubber gasket material have been changed (see 5.5; 6.5 of the 2006 edition); g) the range of the bending moment has been changed (see 5.10; 6.10 of the 2006 edition); h) the requirement for leakage performance without gasket has been deleted (see 6.15 of the 2006 edition); i) the requirements for fire resistance have been changed (see 5.17; 6.18 of the 2006 edition); j) a requirement for the equivalent length of mechanical tee products has been added (see 5.18).

Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. The issuing body of this document shall not be held responsible for identifying any or all such patent rights.

This document was proposed by and is under the jurisdiction of the National Fire and Rescue Administration.

The previous edition of this document and of the document it replaces: first published in 2006 as GB 5135.11-2006; this is the first revision.

Introduction

The automatic sprinkler system is a widely used fixed fire protection installation. It consists of components such as sprinklers, alarm valve sets and water flow alarm devices (water flow indicators or pressure switches), together with pipes, valves and water supply facilities, and discharges water automatically to extinguish a fire when one breaks out. Each component is linked to the others and plays its own part in the system, while also having an independent specific function.

GB 5135 Automatic sprinkler systems is divided according to the function of the components of the system. It covers components such as sprinklers, alarm valve sets and water flow alarm devices as well as related products such as pipes and valves, and forms a fairly complete system of standards, intended to provide a basis for design, production, inspection and certification and acceptance for manufacturers, construction units and the bodies and departments concerned. GB 5135 is intended to consist of 21 parts.

Each part states its purpose. Part 11: Grooved pipe couplings and fittings aims to specify the classification, requirements, test methods and inspection rules of the grooved pipe couplings and grooved fittings of automatic sprinkler systems, so that the products connect the water supply pipework of the system reliably. The other parts do the same for their products: for example Part 1 ensures that sprinklers operate by themselves within the intended temperature range and discharge water in the designed pattern and quantity; Part 7 ensures that vane-type water flow indicators output a signal as water flows in a wet system; Part 18 ensures that pipe hangers and supports hold the fire protection pipework firmly; Part 20 improves the corrosion resistance of epoxy-lined coated steel pipes and extends their service life; and Part 23, for sprinklers for glazing separation, ensures that the product cools and protects the glazed elements of a building.

1 Scope

China's mandatory national standard for the grooved couplings and fittings that join the pipework of automatic sprinkler systems. A grooved joint is made by rolling, cutting or casting a ring groove near the end of each pipe or fitting, laying a rubber gasket over the two ends and clamping them with a split housing whose keys sit in the grooves; it goes together with a spanner, with no welding and no threading on site, which is why it has become the usual way of assembling sprinkler mains and risers. But in a fire system the joint is not an ordinary plumbing detail: it has to stay tight under the rated working pressure for years without being used, hold the pipe together under water hammer and vibration, and keep its seal when the gasket is exposed to heat, and a rigid joint and a flexible joint are meant to behave differently when the pipe moves. The standard defines the terms, classifies the products and fixes how their model numbers are formed, sets the requirements for appearance, product parameters, housing, fasteners and gasket, and for vacuum, gas and water tightness, strength, bending moment, deflection, low and high temperature, water impact, vibration, fire resistance and equivalent length, and describes the matching test methods, the inspection rules, marking, instructions for use, packaging, transport and storage. It is used by manufacturers, by certification and testing bodies and by the designers and contractors who specify and accept sprinkler installations. This 2025 edition replaces GB 5135.11-2006 and comes into force on 1 November 2026.

This document defines the terms and definitions of grooved pipe couplings and fittings for automatic sprinkler systems, specifies their classification and model designation, requirements, inspection rules, marking, instructions for use, packaging, transport and storage, and describes the corresponding test methods.

This document applies to the design, production and inspection of grooved pipe couplings and fittings in automatic sprinkler systems.

2 Normative references

The contents of the following documents constitute indispensable provisions of this document through normative references in the text. For dated references, only the edition corresponding to that date applies to this document. For undated references, the latest edition (including all amendments) applies to this document.

GB/T 191 Packaging - Pictorial marking for handling of goods.

GB/T 228.1 Metallic materials - Tensile testing - Part 1: Method of test at room temperature.

GB/T 528 Rubber, vulcanized or thermoplastic - Determination of tensile stress-strain properties.

GB/T 531 (all parts) Rubber, vulcanized or thermoplastic - Determination of indentation hardness.

GB/T 1690 Rubber, vulcanized or thermoplastic - Determination of the effect of liquids.

GB/T 2828.1 Sampling procedures for inspection by attributes - Part 1: Sampling schemes indexed by acceptance quality limit (AQL) for lot-by-lot inspection.

GB/T 3098.1 Mechanical properties of fasteners - Bolts, screws and studs.

GB/T 3098.2 Mechanical properties of fasteners - Nuts.

GB/T 3181 Colour standard for paint films.

GB/T 3512 Rubber, vulcanized or thermoplastic - Accelerated ageing and heat resistance tests in hot air.

GB 5135.1 Automatic sprinkler systems - Part 1: Sprinklers.

GB/T 7306 (all parts) 55 degree sealing pipe threads.

GB/T 7759 (all parts) Rubber, vulcanized or thermoplastic - Determination of compression set.

GB/T 9124.1 Steel pipe flanges - Part 1: PN designated.

GB/T 17241.1 Cast iron pipe flanges - Part 1: PN designated.

3 Terms and definitions

The following terms and definitions apply to this document.

3.1 grooved pipe couplings and fittings - the general term for grooved pipe couplings and grooved fittings.

3.2 grooved pipe couplings - assemblies used to connect grooved pipes or fittings quickly.

3.3 grooved fittings - the general term for the elbows, tees, crosses, reducers and similar fittings, and derived fittings, used in a grooved piping system, whose ends are machined with a ring groove to match the pipe.

3.4 rigid coupling joint - a split clamp at which no relative angular displacement or axial displacement of the adjacent pipe ends is permitted.

3.5 flexible coupling joint - a flexible split clamp at which a certain relative angular displacement of the adjacent pipe ends, and the corresponding axial movement, are permitted (the permitted angular displacement depends on the pipe diameter), but no axial linear displacement is permitted.

3.6 gasket - a rubber sealing ring that uses pressure to improve the tightness of the system, that is, a ring in which additional pressure produces an additional contact force between the ring and the sealing surface.

3.7 rated working pressure - the maximum working pressure permitted for grooved pipe couplings and fittings in service.