This part of ISO 18172 specifies minimum requirements concerning material, design, construction and workmanship, manufacturing processes and testing of refillable transportable welded stainless steel gas cylinders, of water capacities from 0,5 l up to and including 150 l, for compressed and liquefied gases. This part of ISO 18172 is applicable only to cylinders manufactured from stainless steels with a maximum tensile strength of less than 1 100 MPa and a test pressure above 6 MPa (60 bar).