jenalena
Petroleum
- Sep 8, 2009
- 1
I have six tanks that are manifolded together for a blanket gas / vapor recovery system. The tanks have various MAWP and MAWV ratings.
#1
When considering relief, should the relief valves for normal venting/vacuum and/or emergency venting be set for the tank with the lowest MAWP/MAWV, "the weakest link".
#2
When considering a tank with a frangible roof (per API 650), API 2000 allows you take credit for it, in lieu of an emergency relief valve/hatch. (Normal venting & vacuum still applies) My question is, in a system of tanks manifolded together, how do you assume/calculate the pressure that the tank with the frangible roof would accumulate in an emergency (fire)? The reason why I'm concerned is if the accumulated pressure is somewhere at 7 inches of water column (IWC), and a nearby manifolded tank has a MAWP of 2 IWC - couldn't I have an overpressure scenario for the lower MAWP tank?
#1
When considering relief, should the relief valves for normal venting/vacuum and/or emergency venting be set for the tank with the lowest MAWP/MAWV, "the weakest link".
#2
When considering a tank with a frangible roof (per API 650), API 2000 allows you take credit for it, in lieu of an emergency relief valve/hatch. (Normal venting & vacuum still applies) My question is, in a system of tanks manifolded together, how do you assume/calculate the pressure that the tank with the frangible roof would accumulate in an emergency (fire)? The reason why I'm concerned is if the accumulated pressure is somewhere at 7 inches of water column (IWC), and a nearby manifolded tank has a MAWP of 2 IWC - couldn't I have an overpressure scenario for the lower MAWP tank?
