This part of ISO 17467 specifies the general properties of unplasticized polyamide (PA-U) compounds for the manufacturing of pipes, fittings and valves made from such compounds, intended to be buried and used for the supply of gaseous fuels for maximum operating pressure up to and including 4 bar. It also specifies the test parameters for the test methods to which it refers. This part of ISO 17467 specifies a calculation and design scheme on which the maximum operating pressure (MOP) of piping systems is based.