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

[BlackSmoke]

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.

 

[StoneCold]

BlackSmoke
I was interested to hear what others had to say on this issue.
I work at a small chemical plant. I can tell you what we are doing, I won't go so far as to say it is right, but it is what we do.
1. Heat exchangers. If there is a blocked in case or fire case we have relief valves on the shell (utility) side. The process/ tube side relief is done through piping back to the reactor.

1.b. All our reactors have rupture disks to protect the ASME vessel and Relief valves on the jackets to protect against thermal expansion over pressure.

2. I have walked through a few newer designs (a 2000 design) Not every little thing had a relief. For instance I never saw a small filter with a relief valve. They get beat up too easy and are too large for the pieces of equipment for it to work out. I think these are still being balanced financially as a risk/reward isssue.

3. I have never seen a relief valve installed where there was no identifiable case. It might be a huge strech. For instance we have them on our compressed air tanks even though the compressor will not go higher than the ASME rating of the tanks and there is no fire case.

4. What I have seen is the use of one relief valve to serve as relief for an entire system, assuming there are no valves blocking the line.

Like I said, I don't know if what we do is right but hopefully someone wiser will chime in.

Regards
StoneCold