Heat Exchanger Ruling for 2/3 rule eliminate PRV?
Heat Exchanger Ruling for 2/3 rule eliminate PRV?
(OP)
I have a heat exchanger with 1050psi feedwater into the tubes with a 1050MAP rating. The shell is heated with 215psi Steam and has a 700 MAP. Am I required to protect the shell with a Pressure Relief Device as per ASME VIII-div.1 UG-133 (d). Heat exchangers shall be protected with a pressure relief device. I hear some type of ruling is out there for a 2/3 rule that eliminates the PRV for the shell?





RE: Heat Exchanger Ruling for 2/3 rule eliminate PRV?
RE: Heat Exchanger Ruling for 2/3 rule eliminate PRV?
The 2/3's rule would also have to extend to all of equipment/piping on the low pressure side, not just the exchanger shell. Samuelliu is correct about accounting for flashing. There may be additional transient pressure (water hammer) type concerns if the low pressure were liquid full but with steam on the shell this may not be an issue.
http://www.api.org/techinq/PRS/521/521_inquiries.htm#top