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GB/T 48040-2026Glass-reinforced thermosetting plastics (GRP) pipes - Determination of initial ring stiffness (English PDF)

玻璃纤维增强热固性塑料（GRP）管材初始环刚度的测定

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Issued by

State Administration for Market Regulation

Level / Type

National · Recommended

Issue date

July 30, 2026

Implementation date

February 1, 2027

Scope

GB/T 48040-2026 is the English-translated version of 玻璃纤维增强热固性塑料（GRP）管材初始环刚度的测定.

GB/T 48040-2026 is a Chinese national standard on determining the initial ring stiffness of glass-reinforced thermosetting plastics (GRP) pipes. It is equivalent to ISO 7685:2026 and adds provisions for the preload of pipes whose nominal diameters fall outside two ranges.

The standard describes a test method for initial ring stiffness and presents two methods, a constant load method and a constant deformation method. They are equally effective within the specified deformation range and apply to GRP pipes of any diameter.

Its terms include compressive load, radial deflection, relative vertical deflection and mean diameter. ISO 3126 is its normative reference. Issued on 30 July 2026 and applicable from 1 February 2027.

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Document preview — GB/T 48040-2026

National Standard of the People's Republic of China

ICS: 83.140.30
Classification: G 33

Issued by: State Administration for Market Regulation

Foreword
1 Scope
2 Normative references
3 Terms and Definitions

Foreword

This document conforms to GB/T 1.1-2020 "Standardization Work Guidelines Part 1: Structure and Drafting Rules of Standardization Documents".

This document is equivalent to ISO 7685:2026 "Glass fiber reinforced thermosetting plastic (GRP) pipes - Determination of initial ring stiffness".

The following minimal editorial changes have been made to this document.

--Added provisions for preload of pipes with nominal diameters not within the ranges of a) and b) (see note 8.2).

1 Scope

This document describes a test method for the initial ring stiffness of glass fiber reinforced thermosetting plastic (GRP) pipes. Two methods are presented in this document.

The methods (constant load method and constant deformation method) are equally effective within the specified deformation range and are applicable to GRPs of any diameter.

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 to this document.

ISO 3126 Determination of dimensions for plastic components in plastic piping systems (Plastics piping systems - Plastics components - Note: GB/T 8806-2008 Determination of dimensions of plastic components in plastic piping systems (ISO 3126:2005, IDT)

3 Terms and Definitions

The following terms and definitions apply to this document.

3.1 Compressive load

A load applied to a pipe that causes radial deformation of the pipe.

Note: The unit is Newton (N).

3.2 Radial deflection

The change in diameter in the direction perpendicular to the horizontal position of the pipe under radial compressive load (3.1).

Note: The unit is meters (m).

3.3 Relative vertical deflection

y dm The ratio of the radial deformation y (3.2) of the pipe to the mean diameter dm (3.4).

3.4 Mean diameter

The diameter of the circle corresponding to the center of the pipe wall cross-section.

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This preview omits tables, figures, formulas and parts of the technical clauses. The complete document — 7 pages — is available in the English PDF.

Referenced standards

Normative references

ISO 3126

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