This document specifies the requirements of fitness for purpose of assembled polyethylene (PE) piping systems in the field of the supply of gaseous fuels.

It specifies the requirements for electrofusion, socket fusion, butt fusion and mechanical joints.

It specifies the method of preparation of test piece joints and the tests to be carried out on these joints for assessing the fitness for purpose of the system under normal and extreme conditions.

It specifies the test parameters for the test methods referred to in this document.

This document is intended to be used only by the product manufacturer and test laboratories to assess the performance of components in accordance with ISO 4437-2, ISO 4437-3 and ISO 4437-4 when joined together under normal and extreme conditions in accordance with this document. It is not intended for on-site testing of pipe systems.

In conjunction with ISO 4437-1, ISO 4437-2, ISO 4437-3 and ISO 4437-4, this document is applicable to PE pipes, fittings and valves, their joints, and joints with components of PE and other materials intended to be used under the following conditions:
a) a maximum operating pressure (MOP), up to and including 10 bar1), at a reference temperature of 20 °C for design purposes;
b) an operating temperature between −20 °C and 40 °C.

For operating temperatures between 20 °C and 40 °C, derating coefficients are defined in Annex A.

The ISO 4437 series covers a range of MOPs and gives requirements concerning colours.