ISO 21307:2009 establishes general principles for the process used in the construction and quality assessment of butt fusion joints incorporating fittings (ISO 8085-2) and pipes used in the construction of gas (ISO 4437) and water (ISO 4427) distribution systems, made from PE 80 and PE 100 materials having a melt flow rate at 190 °C/5 g of between 0,3 g/10 min and 1,7 g/10 min, with equipment which complies with ISO 12176-1 and installed in accordance with ISO/TS 10839.

Also specified are a number of proven butt fusion jointing procedures for pipes and fittings with a wall thickness up to and including 70 mm, the materials and components used, the fusion jointing procedure and equipment, and the quality assessment of the completed joint.