If Plant is designed for supposed 40 years, then how to calculate the Stress range Reduction factor.

ASME 31.3 give equation to calulate "f" based on NO. of Cycle. (eqn. 1c)

But In my project , we know only Life of Plant .

One suggestion, we design the plant considering 20yrs of life (i.e. one cycle per day) with this we can go ahead for 40 yrs as no of cycle= 14000-15000. This needed to be discussed with client before finalizing the calculations.
(Presuming that this is not a power plant since; for power plant the start-up & shutdown time is much longer than that for a process plant).

Any comments are welcome.


Regards,
R.K.

Addition to that, in 2002 code of B 31.3 the relation were provided for no of life cycle and stress range reduction factor, but its been replaced with a graph from 2006 edition.
So you can go with still conservative approch of using the values as 0.8

PS : -finalizing anything, kindly discuss with clinet and take proper approval.

Regards,
R.K.

Thanks RK for your valuable suggestion.