Plate & Frame Heat Exchanger TWO rules of thumb

[Iomcube]

I read somewhere that for P&F HX there were two limits (that now I cannot recall). The limits were something like

1] Rate of change of temperature should be less than x degC/min (It mentioned that same HX is sometimes used to heat or cool process fluid so a delay must be incorporated in control logic to execute a delay of say 120sec before changing cooling<>heating mode)

2] Rate of change of pressure should be less than y bar/min (Because I cannot find the source now; it mentioned that because of low holdup volume valve closures should be steady & water hammers should be avoided)

API reference / or any other source will be highly appreciated

 

[Iomcube]

Anyone can shed some light here?

 

[georgeverghese]

Derivation of the permissible ramp rates for P/T in pressure vessels is discussed in some appendix of the ASME Section 8 - see if you can get help from an experienced mechanical engineer for these thermal fatigue concerns.

 

[georgeverghese]

You may get more responses to this on E-tips if you were to repost in Mechanical Engineering - Boiler / Pressure Vessel Engineering, and retitle this as thermal fatigue guidelines for heat exchangers or similar.