Respect to valve that are used in offshore oil and gas industry. A perticular manufacturer supply us valves complying all the testing and specification requirement. But it is observed the all those valves start passing within a very short span of time. Therefore, I would like to know what are the things that is required to review during finalisation of purchase specification. ANSI B16.104 is obsolete and withdrawn. See FCI 70-2 for Control Valve Seat Leakage. This is much greater leakage than required by API STD 598. It is common for new valves to meet the zero bubble requirement in API STD 598 when new. Sand was already mentioned. The nasty rusty hydrostatic testing fluid is often left in the lines for a prolonged period leaving scale and such in the seats. Such practices cause the valves to leak even during the initial startup. Some attempts to fix the problem include adjusting the limit stops to get a fresh piece of the seat into service in addition to the lubrication tricks.

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