Hi to all readers,
If Code Compliance for Design case is 98% then in What Time period for Design temperature and Design Pressure can hold the pipe line stable with out serious damage to line.
actually when pipe line goes Design conditions Operation guys in plant control the valve percentage of opening and closing, So When our Design code stress is at 98% then we can assume in an Hour or less there will not be any problem, as they are tunning down the valve to operating condition.
So, my question is even at 98% code stress line will be safe for 1 hour or more/less.

Thank you for replying.

Runner,

I pressumed that you are using code ASME B31.3.

If code compliance for design case is 98% throught the operation of system , then there is no problem.further to this As per ASME B31.3 section 302.2.4 says,subjected to owner approval it is permissible to exceed allowable stress for pressure design at the temperature of increased condition by not more than
(a) 33% for no more than 10 h at any one time and no more than 100 h/y, or
(b) 20% for no more than 50 h at any one time and no more than 500 h/y
The effects of such variations shall be determined by the designer to be safe over the service life of the piping system by methods acceptable to the owner. (See Appendix V.)

However it is adavisable to maintain some buffer to allowables.

Regards

hi JaganNarayan,

Yes, I am following ASME B31.3 in my Steam Header System, Your information is very valuable, I have read 302.2.4 full content from ASME 31.3.

Thank you soo much for your quick reply.