Low temperature issue
Low temperature issue
(OP)
Friends,
We've a scenario in one of our gas plants: A106B 14" piping sch 80, WT 0.75" (no PWHT) is installed for design pressure 15MPa. Normal operating 3.5MPa, max pressure the system will see is 10MPa. As per curve B, the min temp it can go is -10degC without impact test. In winter months, the pipe can see temp below -15degC becoz of some J-T effect across the throttling valve. Is this permissible to operate below -10deg without impact test. Can we apply temp reduction factor in Fig 323.2.2B?
We've a scenario in one of our gas plants: A106B 14" piping sch 80, WT 0.75" (no PWHT) is installed for design pressure 15MPa. Normal operating 3.5MPa, max pressure the system will see is 10MPa. As per curve B, the min temp it can go is -10degC without impact test. In winter months, the pipe can see temp below -15degC becoz of some J-T effect across the throttling valve. Is this permissible to operate below -10deg without impact test. Can we apply temp reduction factor in Fig 323.2.2B?





RE: Low temperature issue
From "BigInch's Extremely simple theory of everything."
RE: Low temperature issue
Steve Jones
Materials & Corrosion Engineer
http://www.linkedin.com/pub/8/83b/b04
RE: Low temperature issue
RE: Low temperature issue
Regards,
SNORGY.
RE: Low temperature issue
Stress is not evaluated in the corroded state? Forces and moments would be higher, but resulting stresses would be lower. I'd have to take issue with that procedure.
From "BigInch's Extremely simple theory of everything."
RE: Low temperature issue
Maybe I was ambiguous, but what I meant to say is that by my interpretation, you assume strong uncorroded pipe to compute the forces and moments, and then take those forces and moments to evaluate the stress levels in corroded pipe. So thick wall pipe force divided by thin wall pipe area makes for higher stress. By my interpretation of 323.2.2 anyway.
Regards,
SNORGY.
RE: Low temperature issue
From "BigInch's Extremely simple theory of everything."