Isolation procedures question
Isolation procedures question
(OP)
I am trying to find some isolation procedures for using double block and bleed valves, when/where to use them and procedures for PSV isolation, when/where. I really would just like to be pointed in the right direction for some reading material. I have already tryed to go through ASME and CSA code, but it is not of to much help. If there are any good write ups on double block and bleed procedures and PSV isolation procedures I would really appreciate it.
Thanks!
Thanks!





RE: Isolation procedures question
Cheers,
gr2vessels
RE: Isolation procedures question
RE: Isolation procedures question
http://www.standard.no/PageFiles/1134/P-001e5.pdf
Best regards
Morten
RE: Isolation procedures question
RE: Isolation procedures question
http://siri.uvm.edu/ppt/powerpt.html
http://siri.uvm.edu/ppt/lockout/index.htm
RE: Isolation procedures question
RE: Isolation procedures question
Correct the DBB is to provide positive isolation. The full intent is for positive and verifiable isolation. First block valve provides isolation, bleed is the point where isolation is verified (first valve is holding), second isolation is braces for the belt, if the first valve fails the energy source (pressure, chemical, electrical etc) is bled off through the bleed while the second valve holds.
For references try OHS authorities or pressure vessel inspection procedures.
Mark Hutton
RE: Isolation procedures question
Definitely operationally Positive Isolation is the main duty of Double Block& Bleed system.
At times it's supplemented with sealing Or Chain-Lock system
Hope this helps
Best Regards
Qalander(Chem)
RE: Isolation procedures question
"The safe isolation of plant and equipment"
Oil Industry Advisory Committee, HSE Books 1997
For PSV, if there are 2 PSV's and one is 100% spare, the spare one shall be locked closed in order to avoid error in leaving the spare operating (this would result in chattering of PSV's).
RE: Isolation procedures question
These use a matrix that shows pressure, flammability, temperature etc and reads out a standard based on the criteria. For example a 6" oil line may require a higher level of isolation than a 48" water line