PSV's and Applicability of 2010 ASME Sec VIII Div 1 to Heat Exchangers 1

[BlackSmoke]

Reposting after I got no responses over at the chemical engineering section, looks like a way better match here.

There's been a lot of debate among my colleagues and clients regarding the interpretation of the ASME code for pressure vessels and heat exchangers. Unfortunately, much of our experience base is dated, and we may not have kept up with the changing times.

We are the technology licensors, so we ultimately do not bear responsibility for deciding whether vessels must be code-stamped. However, we attempt to specify and illustrate the equipment per ASME standards as a general guideline.

Chemical process industry heat exchangers should fall under the pressure vessel code and we have been specifying them as such. Due to this, as it appears to be stated in the 2010 ASME Section VIII Div 1 standard, pressure-reliving devices must be supplied for all equipment, regardless of size and regardless of whether an overpressure case can be identified.

1) Does this mean that all code-stamped exchangers must be fitted with relief valves on both sides? Even small ones fabricated from standard pipe?
2) Are other designers/operators out there actually putting this into practice? Have you seen this at operating plants?
3) Are they providing nominally sized valves where there is no identifiable overpressure case?
4) Are even very small "vessels" equipped with PSV's? i.e. a small filter housing, which we've previously considered part of the piping system, and probably fabricated from standard pipe.

Thanks in advance for any guidance on these issues.

 

[metengr]

This information is addressed in the Introduction of ASME B&PV Code, Section VIII, Div 1. Obtain a copy and carefully review it.

 

[BlackSmoke]

I took another read through the introduction. One might argue that the filter housings I am interested in could be classified as "strainers" as part of the piping system, though if anyone has a differing experience I'd like to know. This probably comes down to local regs at site, and whether the vessel is code stamped or "constructed to code."

My reading the code also seems to suggest that anything called a heat exchanger falls under these codes and must be protected by a PRV, according to the intro and UG-125. However, if the exchanger is fabricated from standard pipe, is it part of the piping system? Thus, my question still stands:
Have people seen PRV's used to protect both sides of heat exchangers fabricated from standard pipe in the field? (for exchangers larger than the 150 mm ID excluded from the code)

Further, it is still not clear to me that I need to protect the vessel if there is no overpressure scenario identified. (i.e. all source pressures are protected with PSV's at or below setpoint, and material cannot change phase due to blocked in fire.) An engineer at a company reviewing our work has asserted that code requires PRV's on all coded vessels, regardless of if there is a case or not.

Thanks for the initial recommendation.

 

[SnTMan]

BlackSmoke, see UG-125. This paragraph permits, among other things, pressure relief devices (if required) to be installed at locations other than on the vessel. See also UG-140.

Regards,

Mike

 

[metengr]

BlackSmoke;
First and foremost, local Jurisdictional rules or regulations must be evaluated to determine if the object is exempt from regulation. This review is separate and must be performed. If the local regulations default back to B&PV Code, you follow the Introduction/Scope of the Code to determine if the object falls under code rules for fabrication, PRV devices and stamping.

My interpretation of code space - pipe conveys fluids and is not a heat exchanger. Piping can be used as a subcomponent in a heat exchanger, but by itself, it is not a heat exchanger.

 

[MJCronin]

I believe that this is an important topic and could be clarified with a some example configurations.

Perhaps some example configurations where the API rules for HX shell protection from tube rupture would also be useful.

This is an excellent thread with some fine participants !!