Sawsan311
Chemical
- Jun 21, 2019
- 303
Dear All,
I need your views on the following: some design guidelines consider specific remote contingency scenarios where they state that since they are possible but remote, the accumulation to be considered when designing the PSV is the corrected hydrotest pressure in place of the code allowable accumulations, for example, tube rupture, gas blowby with bypass valve in open position, failure of operator response, blocked outlet due to check valve failure. On the other hand, API 521 didn't directly state the accumulation to be considered for such remote but possible scenarios and instead only uses the corrected hydrotest pressure as an upper limit for accepting the use of administrative controls without a PSV or as a criteria for addition risk mitigation.
My question is: if we following the aforementioned design guideline, would we be violating ASME SEC VIII code UG-125 which clearly states the allowable accumulation of 10%, 16% and 21% when a PRD is installed. I could deduce from API 521 7th edition language that it has recently updated its write-up to ensure no violation of the UG-125. Even UG-133 addresses the heat transfer equipment which requires the overpressure protection in accordance with the allowable accumulation.
Appreciate your views.
I need your views on the following: some design guidelines consider specific remote contingency scenarios where they state that since they are possible but remote, the accumulation to be considered when designing the PSV is the corrected hydrotest pressure in place of the code allowable accumulations, for example, tube rupture, gas blowby with bypass valve in open position, failure of operator response, blocked outlet due to check valve failure. On the other hand, API 521 didn't directly state the accumulation to be considered for such remote but possible scenarios and instead only uses the corrected hydrotest pressure as an upper limit for accepting the use of administrative controls without a PSV or as a criteria for addition risk mitigation.
My question is: if we following the aforementioned design guideline, would we be violating ASME SEC VIII code UG-125 which clearly states the allowable accumulation of 10%, 16% and 21% when a PRD is installed. I could deduce from API 521 7th edition language that it has recently updated its write-up to ensure no violation of the UG-125. Even UG-133 addresses the heat transfer equipment which requires the overpressure protection in accordance with the allowable accumulation.
Appreciate your views.
