9Cr-1Mo material creep VS mechanical properties

[hcjulien]

I have a heater tube made from A200 T9 (9Cr-1Mo) operating at 500 PSIG and 725F. In is working life, several times (Qty: 10) the tube has reached 1000F at the same pressure. Today I have to evaluate if a localized thin area is acceptable to operate for the next two years.

Supposing that we will not reach a temperature more than 800F in the next two years, can I suppose the same mechanical properties (yield and ultimate strength) as described in ASTM A200 or the creep damage has reduced the mechanical properties of my T9 alloy?

Thanks in advance,

hcjulien

 

[stanweld]

I suspect that any localized thinning was not due to Creep but more likely due to corrsion. How long has the tube been in service and what was the service? I would suspect in crude oil having appreciable sulfur.

 

[metengr]

The mechanical properties should be near the same as specified, based on the conditions you stated above. What I would suggest is to use API 579 to evaluate the effects of locally thinned areas (LTA).