BS ISO 18172-2 pdf download Gas cylinders — Refillable welded stainless steel cylinders — Part 2: Test pressure greater than 6 MPa 4 Materials and heat treatment 4.1 General 4.1.1 Materials of shells and end pressings shall be stainless steels in a condition suitable for pressing or drawing and welding, and shall conform to ISO 9328-7. 4.1.2 Grades of steel...