HEAT EXCHANGER RELIEF VALVE - API 521 6th edition

[macabihaifa]

Hello,
According to API 521 a relief valve is not required in the case of tube rupture if the design pressure of the low side pressure is 10/13 of the high pressure design pressure.
For example: if the high pressure side design pressure is 26 barg we set the design pressure of the low side pressure to 26*10/13=20 barg ( since the test pressure of the low side will be 20*1.3=26 barg which is equal to the design pressure of the high pressure side so no hazard will occur in the scenario of tube rupture).
All this preview was for my asked clarification where is detailed (may be with a numerical example) in API 521 6th edition 2014?

regards,
roker

 

[georgeverghese]

Yes, your assessment is correct. But you still need to account for this tube rupture relief at some other LP side connected component ( some other vessel ? ) where the design pressure is less than 26barg. This also means the LP side exit isolation valves will have to be locked open and operated only under work permit. A PSHH on the the LP side should also auto close the HP side feed if this PSHH is triggered.