aggieengineerrmb
Mechanical
We are considering modifying one of our standard, API 6D flanged floating ball valves for use in a cryogenic application with the potential for temperatures as low as -150F. It's a shutdown valve going in front of a relief valve. Normal operating temperature is literally ambient, however in the event the relief valve blows, it's possible that the valve might see -150F. The valve is always open, and would only be closed if there is an event. This valve does not have extended bonnets, and customer understands that the valve might ice over and he would not be able to operate it until it warms up.
Our normal low temperature for this particular valve has historically been -50F due to the limitations of the o-rings used to seal the stem and between the body and the adapters. I can see no reason that we should not be able to rate this valve down to -150F for this service if we replace the o-rings with special spring energized PTFE lip seals. The materials for the body/adapter/ball are 316SS and the seats are Devlon, which both appear to easily handle these temperatures.
Does anyone know of something I might be overlooking that would cause problems?
Our normal low temperature for this particular valve has historically been -50F due to the limitations of the o-rings used to seal the stem and between the body and the adapters. I can see no reason that we should not be able to rate this valve down to -150F for this service if we replace the o-rings with special spring energized PTFE lip seals. The materials for the body/adapter/ball are 316SS and the seats are Devlon, which both appear to easily handle these temperatures.
Does anyone know of something I might be overlooking that would cause problems?
