SCHEDULE 4Gas Containers

Part IISpecification for brass or bronze valves

Manufacture of valves

1.  The stamping or pressing from which a valve is manufactured shall be made from bars produced by (a) extrusion, (b) rolling, (c) forging, (d) extrusion and drawing, or (e) rolling and drawing.

Heat treatment

2.  Stamping or pressing shall be heat treated so as to produce an equiaxed microstructure in the material.

Freedom from defects

3.  Stampings, pressings and the bars from which they are made shall be free from cracks, laminations, hard spots, segregated materials and variations in composition.

Tensile test

4.  Tensile tests shall be made on samples of stampings and pressings taken at random from any consignment. The result of the tensile test shall conform to the following conditions—