This part of ISO 9809 specifies minimum requirements for the material, design, construction and workmanship, manufacturing processes, and tests at manufacture of refillable quenched and tempered seamless steel gas cylinders of water capacities from 0,5 l up to and including 150 l for compressed, liquefied and dissolved gases exposed to extreme world wide ambient temperatures (normally between −50 °C and +65 °C). This part of ISO 9809 is applicable to cylinders with a maximum tensile strength R_m of greater than or equal to 1100 MPa. It does not cover cylinders with R_mmax. > 1 300 MPa for diameters > 140 mm and guaranteed wall thicknesses (a′) ≥ 12 mm, and R_mmax ≥ 1400 MPa for diameters ≤ 140 mm and guaranteed wall thicknesses (a′) ≥ 6 mm, because beyond these limits additional requirements may apply.