Particular attention is drawn to so

Particular attention is drawn to some relevant factors as follows: a) if a major rupture of the valve should occur at some stage during application of pressure, considerable energy will be released; hence no personnel should be in the immediate vicinity during pressure raising (for example a given volume of air contains 200 times the amount of energy that a similar volume of water contains, when both are at the same pressure); b) the risk of brittle failure under test conditions shall have been critically assessed at the design stage and the choice of materials for valves that are to be pneumatically tested shall be such as to avoid the risk of brittle failure during test. This necessitates provision of an adequate margin between the transition temperature of all parts and the metal temperature during testing; c) attention is drawn to the fact that if there is a reduction in gas pressure between the high-pressure storage and the valve under test, the temperature will decrease. Valves undergoing pneumatic test should not be approached for close inspection until after the pressure increase has been completed. No valve undergoing pneumatic test shall be subject to any form of shock loading. Precautions shall be taken against pressures generated in excess of test pressure. 6.5 Adjustment of set or cold differential test pressure Each safety valve shall be adjusted to its designated set or cold differential test pressure. Before adjusting a safety valve to the set or, if applicable, cold differential test pressure using air or other gas as the test medium, it shall previously be subjected to a hydrostatic test (see 6.3). 6.6 Seat leakage test The seat leakage test of a safety valve shall be carried out after adjustment of the set or cold differential test pressure. The test procedure and leakage rate shall be agreed between the manufacturer and the purchaser. NOTE For example, API 527 can be used. 7 Type testing 7.1 General 7.1.1 Application The operating and flow characteristics of safety valves shall be determined by type tests in conformity with this clause. — This clause applies to the types of safety devices defined in 3.1.