This International Standard specifies two alternative methods for determining the long-term hydrostatic strength of multilayer pipes: a calculation method applicable to multilayer P pipes (all polymer layers) and a test method applicable to both multilayer P and multilayer M pipes (polymer and metal layers). This International Standard is not applicable to pipes consisting of one polymeric stress-designed layer or having an outside polymeric layer that is not stress-designed. Those types of multilayer pipe are covered by the International Standards referenced in Clause 2.