ISO 9809-2:2019

This document 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 with water capacities up to and including 450 l.
it is applicable to cylinders and tubes for compressed, liquefied and dissolved gases and for quenched and tempered steel cylinders and tubes with an actual tensile strength Rma ≥ 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 a′ ≥ 12 mm and for cylinders and tubes with Rma, max > 1 400 MPa for diameters ≤140 mm and guaranteed wall thicknesses a′ ≥ 6 mm because, beyond these limits, additional requirements can apply.