Downstream pipe design conditions of a drain valve that is capped
Downstream pipe design conditions of a drain valve that is capped
(OP)
Shouldn't the pressure/temperature rating in the downstream piping stub of a normally closed isolation valve be the same as upstream of the valve?





RE: Downstream pipe design conditions of a drain valve that is capped
RE: Downstream pipe design conditions of a drain valve that is capped
Begs the question why this stub is there in the first place??
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RE: Downstream pipe design conditions of a drain valve that is capped
RE: Downstream pipe design conditions of a drain valve that is capped
Certainly the start of a drain line may see full pressure. But the discharge end may never get this high.
Generally we design drain lines for upstream pressure. We may reduce this for EQ design.
RE: Downstream pipe design conditions of a drain valve that is capped
I have seen capped valves used for vent and drains in steam power plants. These are required for venting and draining during hydro test. Once hydro test is complete those valves are cap welded. My only guess this is done just make sure that nobody should open those valves after hydro test, because of high pressure high temperature steam inside lines.
If in the future you need to conduct another hydro test (for instance, maintenance or replacement of the lines), they only need to cut one fillet weld to have vents and drains.
Regards,
Curtis