ISO 14531-3:2010 specifies the physical properties and mechanical-performance requirements for full-end-load-resistant mechanical fittings for use in the connection of crosslinked polyethylene (PE‑X) pipes conforming to ISO 14531‑1 and in the construction of transition assemblies for joining PE‑X pipes to metal pipes having plain spigot, screw thread, compression socket and flange terminations. In addition, it lays down dimensional requirements and specifies some general material properties (including chemical resistance) together with a classification scheme for PE‑X fitting materials produced in the form of pipe. ISO 14531-3:2010, when used in conjunction with the other parts of ISO 14531, provides the basis for the design, manufacture and installation of PE‑X piping systems (PE‑X pipes, PE‑X fusion fittings and mechanical fittings) for the supply of category D and category E hydrocarbon-based fuels.