Flange Max Test Pressure

[merton]

When we get into the 2500# ANSI stuff I'm having a couple problems figuring out the max test pressures on the 2500# Flanges. What we're looking at is an customer spec flange (ASME 2500 RTJ, ASTM A 350 LF2 CL-1, ASME B 16.36). Now in all technicality we classify it as a Z662 flange, but our customers's spec is based off of B31.3. And that is where I guess we are having problems. Neither Z245.12 or B31.3 are very clear on the pressure test when you get up to these pressures. Some sources I have found say we can test them to 1.25 times the flange rating, which is 41,370 kPa for Z662, but I have been unable to explicitly find that anywhere. The reason that this does not make sense is that as far as the maximum operating pressure goes our pipe is the limiting factor, not the flanges. But, with the maximum strength test pressure it seems to be the flanges that are the limiting factor and we're having a tough time swallowing that. Doesn't seem to make sense. Any light you could help shed on that would be helpful.

 

[deanc]

Try these folks.

http://www.carbertesting.com/CompanyOverview.html

http://www.prci.com/

http://www.pipingdesigners.com/index.htm

 

[unclesyd]

Is it the flange proper or the gasket seating stress that is your limiting factor?

In our process where we use Class 2500 flanges (Group 1.1) it is always the gasket seating that would be the limiting factor. We test at 3700 psig to 3900 psig depending on size. As I recall the design pressure is around 2500 psig at 600F.


I also don't understand the necessity of testing the flange at the maximum allowable pressure as the system design conditions should dictate the test pressure.

 

[unclesyd]

I forgot to state the allowable pressure at ambient for the Class 2500 (Group 1.1). It is 6170 psig. The max test pressure at the same conditions is 9275 psig which is a 1.5 multiplier.

 

[BigInch]

No sense testing to max flange test pressure if the connecting pipe blows in the process. Test the flanges only to the test pressure required to operate the completed system at its design pressure.

http://virtualpipeline.spaces.msn.com