Hi All,
Manual depressurization line around PSV has an isolation valve [ball valve] and a globe valve downstream of this. Shell DEP suggests that minimum distance between this two valve to be minimum 600 mm.
Reason is not clearly mentioned for this. It looks during manual depressurization through this globe valve [ especially for high pressure system] downstream of this valve will see lower temperature. This cold temperature will cool down metallic pipe and via conduction cold temperature will flow backward and manual operation of isolation valve will be problematic due to frosting/freezing of air.
In another scenario, if we need to install a RO in addition to globe valve then what would be the best location of this RO ?
(1)downstream of globe valve as distance between globe valve and upstream isolation valve will be 600 mm minimum.
(2)RO just after ball type isolation valve. Distance between ball and globe valve will be 600 mm.
Please share your opinion.
Regards,