Testing 25 bars pressure at 250C? 5

[amockalypsenow]

Howdy all,

I trying to proof test a prototype pipe flange cap that will be mounted to a 300 series 3" vessel that is designed to a limit of 25 bar and 250c.

The pressure is a no-brainer, but I wonder if there is a way to safely test the temp concurrently. I am in communication with my local (so cal) hydrotest providers but none I have contacted really have this experience.

The vessel is designed to contain oil.

Anybody have experience with this?

Thanks in advance,

Cameron

 

[racookpe1978]

Well, as the doctor once said, we have some good news, and some bad news.

The good news is you are testing for oil as the contained fluid (not water - with its high expansion as the water tries to become steam at that pressure-temperature - made even more dangerous as it flashes to saturated steam if a leak/fracture were to develop during the test.

the bad news, however, is that oil (any hydrocarbon) will be dangerously flammable/explosive after leaking at that high a pressure-temperature into the atmosphere.

I do not recall the chapter and verse of the requirement, but I believe you test to the pressure required for the 1.3 x MAWP requirement corrected for the room temperature of the test - testing with a non-flamable liquid that is safe for the process. (That the test fluid will not contaminate the tank and piping if the test fluid cannot be cleaned completely after the test.)

Note that a typical metal loses strength as it heats towards 250 deg C, so the 1.3 MAWP test pressure at room temperature is further from the failure point of the metal 25 deg C than it is at 250 C.

 

[TGS4]

Test it at rink temperature. Ratio the pressure by the allowable stress at room temperature to the allowable stress at your elevated temperature. UG-99 stuff.

 

[GenB]

The material is already proven to hold the temp at certain pressure. A hydrostatic test will be for safety

 

[r6155]

Pressure test is the way to simulate design pressure and temperature to verify the work made during fabrication

Regards
r6155

 

[pdiculous963]

He's trying to proof test, not hydrotest. Read UG-101. Basically you perform the proof test at room temperature and compute the MAWP at room temperature. Then you multiply the MAWP at room temperature by the ratio of allowable stress at design temperature to that at room temperature to determine the final MAWP at the design temp.

 

[EdStainless]

If you want to burst one, you could look at a PAO synthetic oil.
they have very high flash points (over 500F) and handle well.
Just by some pure 8cSt PAO (unblended with no additives).

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P.E. Metallurgy, Plymouth Tube