how to measure high temperature creep

[Steven23144]

As a vessel was requested to be designed in according with ASME Section VIII Div.2 or API 579, the design temperature is 560 degree C, operating temperature is 530~550 degree C and the design pressure 3.8 bar. the used material is SA-387-22
we would like to know how to measure high temperature creep may be incorporate in calculation.

Thanks a lot

Steven

 

[racookpe1978]

You can't "measure" high temperature creep ..... until it occurs.

You could scribe two marks a specific difference apart (10 feet = 120.000 inches for example, 2 meters = 2000.0 mm apart, or whatever) then measure the scribed distance at every outage.

 

[metengr]

You can determine the approximate creep rupture life at the stated design conditions by calculation using well known parametric equations, like the Larson Miller parameter or Monkman-Grant.

 

[racookpe1978]

You can determine the approximate creep rupture life at the stated design conditions by calculation using well known parametric equations, like the Larson Miller parameter or Monkman-Grant.

Concur. Before long-term operation at high temps, you can only "anticipate" the effect of creep using those estimates.

 

[EdStainless]

In some alloys you can see the effect of creep in the microstructure.
So plans are made to remove samples (cut plugs) out at various intervals in order to see if the actual creep damage is similar to what was predicted.
Creep goes through stages, and you need to know before you reach the final stage, because that is always failure.
All devices designed to operate in the creep limited regime have a finite service life.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

 

[metengr]

There are advanced NDT techniques, like linear and annular phased array UT in conjunction with surface replication, in lieu of taking samples, which results in time consuming and costly weld repairs.