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Creep temperature without pressure

Creep temperature without pressure

Creep temperature without pressure

Hello all, i have a question for the members of this forum :
we have on site a fuel gas engine who's exhaust gas temperature is around 600 degrees Celsius . These gases pass at atmospheric pressure throw a carbon pipe ( SA-106 Gr.B ) before being cooled .As per ASME B31.3 creep range for this material starts at 375 degrees Celsius .
We have raised concerns to the manufacturer of the skid that the pipe will go into creep , however the manufacturer is arguing that because no pressure goes throw that pipe ASME B31.3 is not applicable and thus it will be no problem if the pipe goes into creep range.
I tried to search in B31.3 but i have found no definitive answer whether creep is dependent on pressure or not.
Please help clarify if the manufacturer is right or we are.( with a quote from any standard is better :) ).
Thank you.

RE: Creep temperature without pressure


These gases pass at atmospheric pressure throw a carbon pipe ( SA-106 Gr.B ) before being cooled
Is this the exhaust pipe and vent the gas to atmospheric?
Otherwise, it should have some pressure to push the gas through the pipe to the cooler(?). Is it correct?
Instead of A106-B, can it be replaced with a SS pipe?

RE: Creep temperature without pressure

Creep deformation requires stress over time at temperature. Although there is may be no pressure, there is still stress due to self-weight. Nevertheless, that may be within acceptable limits.

At that temperature, though, there are other metallurgical phenomenon taking place. Consult a metallurgist.

What are the consequences if this component suffered a catastrophic failure?

RE: Creep temperature without pressure

Self-weight (as pointed out above) adds to the constant vibration forces on that pipe.

Any exhaust pipe is supported at only one end - the outlet is "pointed out towards the sky" (almost be definition) so the pipe outlet forces always act against the middle of the pipe (which is never straight) and so is never firmly supported at both ends.

Only you can determine how far the pipe will droop until it is no longer usable, hits insulation or other engine parts, hits the hole in the sheetmetal around the engine and enclosure, rusts out the sheetmetal from heat and constant vibration, melts the insulation or rubber around the exhaust, or just looks sloppy in the customer's plant.

RE: Creep temperature without pressure

Thank you all for your answers .
A clarification is in order here : this is the path of the gases : fuel gas engine - flexible connection - housing of the flame arrestor - pipe ( this is the pipe in question ) between the housing of the flame arrestor and an heat exchanger that cools the gasses -cooler - catalyst - exhaust.
The pipe is connected to both ends : 1 to the housing of the flame arrestor , 2 to the cooler .

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