This part of ISO 15439 specifies the general properties of polyamide (PA) 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 15439 specifies a calculation and design scheme on which the maximum operating pressure (MOP) of piping systems is based.