This part of ISO 10838 specifies requirements and test methods for full-end-load-resistant mechanical pipe-jointing systems for connecting, to each other or to a fitting or as a lateral connection to a polyethylene main (branching or lateral connection), polyethylene (PE) pipes, conforming to ISO 4437, of nominal outside diameter smaller than or equal to 63 mm. In addition, it specifies certain general properties of the material from which these fittings are made. This part of ISO 10838 specifies dimensional requirements for, and the performance of, such assemblies. It is applicable to mechanical fittings with thermoplastics and/or reinforced-thermoplastics load-bearing components intended for use with PE pipes designed for the supply of gaseous fuels, to produce either permanent joints or joints which can be dismantled. If intended for assembly with a metal pipe or fitting, such connections may comprise compression joints or flanged or fused connections. This part of ISO 10838 is applicable only to mechanical fittings with normal operating-temperature limits between – 20 °C and +40 °C, unless otherwise agreed between the interested parties. It is the purpose of this part of ISO 10838 to provide performance requirements that will ensure that mechanical pipe-jointing systems will provide full sealing and full restraint of the PE piping so that the PE piping will yield rather than pull out of the mechanical joint when subjected to tensile forces or pressure.