my manager has told that code stress ratio always greater in expansion case than sustain case. is it possible when pressure is high, temperature is low condition. can you help me, please?
is there any base for that?

Maybe he meant the allowable stress is always greater for expansion than sustained. That is true, but the statement you quote is of course rubbish.

In feed water line for boilers having 100bar press, temp.100c is possible case for code stress ratio higher in sus than exp. right?

There is any number of scenarios where the sustained stress ratio will exceed the expansion stress ratio .... And vice versa. They are only numbers ...What is the problem with this ?

can you illustrate some examples for me, please?

Good grief. Think of a very flexible, very high pressure pipe system. The sustained stress could be easily more than the expansion stress.

thank you my friend, but my colleagues doesnot accept this, even my manager too, how can i convince them?
any reference? please.

What I have said is that it is POSSIBLE for SUS to exceed EXP stresses.

Take a hot, straight pipe, anchored at one end with decent teflon type supports. Just guide the other end. May be an expansion bellows there for example.

Now pump it up to some pressure near its max allowable.

There is practically no thermal stress ... it's just a straight pipe expanding freely. The sustained stress due to pressure will be close to allowable. Q.E.D.

If your colleagues and your manager still cannot understand this, I suggest they open their eyes and get some basic engineering education sorted out for the entire office.

THANK YOU FOR YOUR VALUABLE SUGGESTION, MY FRIEND.
CAN YOU ASSIST WHICH BOOK IS GOOD FOR KNOWLEDGE IN STRESS ANALYSIS.

Try the 'Search' facility.