6 Production testing 6.1 Purpose Th

6 Production testing 6.1 Purpose The purpose of these tests is to ensure that all safety valves meet the requirements for which they have been designed without exhibiting any form of leakage from pressure-retaining components or joints. 6.2 General It is permissible to adopt an alternative test of equal validity (e.g. proof of design tests associated with statistical sampling) to the hydrostatic test for valve shells with: — threaded ends; and — a maximum inlet diameter of 32 mm; and — a ratio of bursting pressure to design pressure of at least 8; and — a design pressure equal to or less than 40 bar; and — for use with non-hazardous fluids; and also for valves as above but with: — a design pressure greater than 40 bar; and — a ratio of bursting pressure to design pressure of at least 10; and — material which is either wrought or forged. All temporary pipes and connections and blanking devices shall be adequate to safely withstand the test pressure. Any temporary welded-on attachments shall be carefully removed and the resulting weld scars shall be ground flush with the parent material. After grinding, all such scars shall be inspected by using magnetic particle or fluid penetrant techniques. 6.3 Hydrostatic testing 6.3.1 Application The portion of the valve from the inlet to the seat shall be tested to a pressure 1,5 times the manufacturer’s stated maximum pressure for which the safety valve is designed. The shell on the discharge side of the seat shall be tested to 1,5 times the manufacturer’s stated maximum back pressure for which the valve is designed. This pressure can be lower than that given by the outlet flange rating.