aggieengineerrmb
Mechanical
- May 27, 2003
- 28
Does anyone know what the expectations are in the industry for sealing quarter-turn, trunnion mounted ball valves when using PEEK as the materail for the seat?
All the valves I am concerned with are API-6D complaint, and I know that this standard requires zero leakage between the ball and seat, with H20 or a gas like air or N2. We can achieve a reasonably reliable seal using H20 as the test media, but really struggle getting these valves to seal when a gas is used. The problems occur at both high and low pressure, but it is most difficult to achieve a seal at low pressures.
Are there manufacturers out there that can achieve a bubble tight seal reliably with PEEK seats in a gas test. My experience is we can sometimes achieve a seal, but cycle the valve 2-3 times is all it takes to get some minute scratches in the ball and/or seat and small leaks can occur. Are we chasing our tail trying to achieve a level of sealing that no one in the industry really expects or even requires?
All the valves I am concerned with are API-6D complaint, and I know that this standard requires zero leakage between the ball and seat, with H20 or a gas like air or N2. We can achieve a reasonably reliable seal using H20 as the test media, but really struggle getting these valves to seal when a gas is used. The problems occur at both high and low pressure, but it is most difficult to achieve a seal at low pressures.
Are there manufacturers out there that can achieve a bubble tight seal reliably with PEEK seats in a gas test. My experience is we can sometimes achieve a seal, but cycle the valve 2-3 times is all it takes to get some minute scratches in the ball and/or seat and small leaks can occur. Are we chasing our tail trying to achieve a level of sealing that no one in the industry really expects or even requires?
