BS EN 13322-1:2003 – Transportable gas cylinders — Refillable welded steel gas cylinders — Design and construction — Part 1: Carbon steel
4 Materials and heat treatment
4.1 General
4.1.1 Materials supplied for shells and end pressing shall conform to EN 10120, or EN 10028-1 and EN 10028-3,or EN 10028-1 and EN 10028-5.
4.1.2 Materials supplied for bungs shall conform to EN 10083-1 + A1.
4.1.3 Grades of steel used for the manufacture shall be compatible with the intended gas service (e.g. corrosive gases, embrittling gases) in accordance with EN ISO 11114-1.
4.1.4 All parts welded to the cylinder shall be made of compatible material with respect to the weldability.
4.1.5 The welding consumables shall be such that they are capable of giving consistent welds with minimum tensile strength at least equal to that specified for the parent material in the finished cylinder.
4.1.6 The manufacturer shall obtain and provide certificates of the ladle analysis of the steel supplied for the construction of the pressure retaining parts of the cylinder.
4.1.7 The manufacturer shall be able to guarantee cylinder steel casting traceability for each cylinder.
4.1.8 Cylinders for acetylene service shall be manufactured with materials compatible with the manufacturing process of the porous mass, or an internal coating shall be applied.
4.2 Heat treatment
Cylinders shall be delivered in either the normalised or the stress-relieved condition. The cylinder manufacturer shall certify that the cylinders have been heat-treated after completion of all welding and shall certify the process of heat treatment applied. Localised heat treatment of cylinders is not permitted, nor in the case of repaired cylinders.
The actual temperature of heat treatment to which a type of steel is subjected for a given tensile strength shall not deviate by more than 30 °C from the temperature specified by the manufacturer for the cylinder type.
5 Design
5.1 General requirements
5.1.1 The calculation of the wall thickness of the pressure parts shall be related to the yield stress of the parent material.
5.1.2 For calculation purposes, the value of the yield stress R e is limited to a maximum of 0,85 R g .
5.1.3 The internal pressure upon which the calculation of gas cylinders is based shall be the test pressure p h .
5.1.4 A fully dimensioned drawing including the specification of the material shall be produced.
5.1.5 Cylinders for acetylene service shall be designed to allow for a test pressure of at least 60 bar.
5.1.6 Cylinders for acetylene service shall be designed and manufactured to ensure that conditions are safe for the eventual filling of the porous mass, e.g. preventing sharp edges and voids.
BS EN 13322-1:2003 – Transportable gas cylinders — Refillable welded steel gas cylinders — Design and construction — Part 1: Carbon steel