This part of ISO9809 specifies minimum requirements for the material, design, construction and workmanship, manufacturing processes, examination and testing at manufacture of refillable normalized or normalized and tempered seamless steel gas cylinders of water capacities from 0,5l up to and including 150l for compressed, liquefied and dissolved gases. NOTE1 If desired, cylinders of water capacity less than 0,5l can be manufactured and certified to be in compliance with this part of ISO9809 . NOTE2 For quenched and tempered steel cylinders with maximum tensile strength less than 1100MPa, see ISO9809‑1 . For quenched and tempered cylinders with maximum tensile strength≥1100MPa, see ISO9809‑2 .