Conditions from which the cryogenic design is required
Conditions from which the cryogenic design is required
(OP)
Hello everybody,
I just wonder if there is good practices (standards...etc) to determine the need of cryogenic design on gate/globe/ball manual valves, especially when the "cryogenic" conditions appears only during transient or accidental cases?
My project is a piping system with a electrical heating device with manual valves upstream the heater:
- In normal operation, the temperature upstream the heater is +0°C -> cryogenic design is not required for valves for this case
- During transient cases (heater start-up), temperature of fluid upstream the heater can decrease under -70°C during a very short duration (30sec - 1min)
Piping design codes say generally that only long-period (en 13480) or normal operation cases (b31.3) have to be considered for the rating of the valves selection. If I follow this recommendation I don't need cryogenic design on the valves.
Do you have an experience or a standard to share to help me for this subject?
Thank You
F67
I just wonder if there is good practices (standards...etc) to determine the need of cryogenic design on gate/globe/ball manual valves, especially when the "cryogenic" conditions appears only during transient or accidental cases?
My project is a piping system with a electrical heating device with manual valves upstream the heater:
- In normal operation, the temperature upstream the heater is +0°C -> cryogenic design is not required for valves for this case
- During transient cases (heater start-up), temperature of fluid upstream the heater can decrease under -70°C during a very short duration (30sec - 1min)
Piping design codes say generally that only long-period (en 13480) or normal operation cases (b31.3) have to be considered for the rating of the valves selection. If I follow this recommendation I don't need cryogenic design on the valves.
Do you have an experience or a standard to share to help me for this subject?
Thank You
F67
Talk To Other Members
RE: Conditions from which the cryogenic design is required
In cases where something can go wrong you should always ask yourself following questions:
What are the worst possible consequences?
What is the cost of the consequences in money / health / life ?
Who bears the responsibillity and the cost?
For mechanical systems 'just a tiny bit of overexposure ' will usually require an upgrade to correct level of construction class. As an example only a small portion of a pressure/temperature curve above allowed level will require use of the higher, correct pressure class.
RE: Conditions from which the cryogenic design is required