This part of ISO 9809 specifies minimum requirements for the material, design, construction and workmanship, manufacturing processes, examination and testing at time of manufacture for - refillable seamless steel gas cylinders and tubes - of water capacities up to and including 450 l - for compressed, liquefied and dissolved gases. - quenched and tempered steel cylinders and tubes with an actual tensile strength Rma e" 1 100 MPa. It is not applicable to: - cylinders and tubes with Rma, max > 1 300 MPa for diameters > 140 mm and guaranteed wall thicknesses a2 e" 12 mm and - cylinders and tubes with Rma, max > 1 400 MPa for diameters d" 140 mm and guaranteed wall thicknesses a2 e" 6 mm, because beyond these limits, additional requirements can apply.