Pressure Test on Air Fan Coolers

[leont]

An Air Fan Cooler has a design pressure of 80 psig, however data issued by process engineering indicates its operating max pressure is 8 psig.

The test pressure should be 1.5*(PD) and it seems to be very big as compared to operating pressure. What is the reason Air Fan Cooler are manufactured for high pressure.

API 661 talks about minimum tube wall thicknesses. Could it be one of the reasons or your experience and knowledge can add something else ?

Regards

 

[SNORGY]

I don't know, but I view it the other way; I think the 80 psig is *right* and the 8 psig seems *wrong*.

I am not aware of too many air coolers that flow much of anything at 8 psi...

What's the service?

Regards,

SNORGY.

 

[gr2vessels]

The Air Cooled Heat Exchangers are considered pressure equipment subject of relevant code and regulations;- the ASME VIII minimum design pressure is 15 psi, hence 8 psi is outside the code jurisdiction.
However, the question you are asking should be addressed to your process engineer, who might have established the 80 psi design pressure for his/her's particular reasons. Alternatively, if you have specified for your air cooler only the operating pressure, it is quite possible that the Vendor has selected an existing cooler designed to the 80 psi, because this was the lowest design pressure available.
Cheers,
gr2vessels

 

[speco]

leont,

I think you and gr2vessels are basically right. The minimum material thicknesses for tubes and header plates, as required by API-661 would easily allow you to use 80 PSIG as the design pressure without any additional cost. It usually pays to stamp the exchanger with the highest design pressure you can, given the actual thicknesses and dimensions of its components. This could save the expense of a re-rate later, should it be needed.

Regards, Speco (

http://www.stoneprocess.com)

 

[leont]

Thank you gr2vessels, speco.

Something like that I have gotten from other text books and co-worker experiences.
Each manufacturer has its own standard and those ones are offer to the clients, who are willing to get them.

Again, thank you so much.