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I am curious to read the input from others regarding the following issue. For years, I have used the design temperature in my pipe stress analysis models for calculating the wall thickness and for expansion stresses. In addition, I have had Notified Body's or third party reviewers check my...

I am just curious. From the notes in appendix A of b31.3 note 57 states "Conversion of carbides to graphite may occur after prolonged exposure to temperatures over 800 F." Why does Caesar II not give any type of warning or error if I am using A106B pipe with operating temperature at 900F?

I am taking another economical approach and not replying to this post further. For you can lead a horse to water , but you can't make the horse drink.

Again... b31.3 piping design is mostly for 175,200 hour design basis in the EPC-stage, take chafe or umbrage if you would like, but this is a fact. I am sure that you will agree the EPC company is not going to design for 50 years design life unless the client specifies to do this because it...

TGS4... I disagree with your thoughts. The allowable stress is used in the expansion stress range. Thermal ratcheting/shakedown occurs, but so does stress relaxation and the possible fact that appendix V could be valid in this situation in which the pipe network only is running at the maximum...

Well, I think I figured it out myself. You can put the model in Caesar and get all of the sustained load cases. Using appendix V instead of using B31.3 straight criteria allowed us to use a 6" schedule 160 pipe versus a 6" special mill run pipe with 0.913" wall thickness. Only one thing to...

If you have the theoretical friction coefficient in your piping analysis along with the appropriate design temperature and pressure and your only coming out to be at 93% of the allowable, I think the system will be fine. You are right, the construction tolerances, actual friction factors, etc...

I am currently trying to understand B31.3 Appendix V Allowable Variations in Elevated Temperature Service. I am hoping to gain some insight on the example given in this appendix. I understand everything until the point where the Stress due to sustained loads is calculated in accordance with...

I am trying to calculate what occasional load factor that I need to use for elevated temperature fluid service. B31.3 para 302.3.6 states that the occasional load factor as an alternative to using 1.33 times the basic allowable stress may be taken as the "strength reduction factor" multiplied...

Thanks you.. last question. Why does b31.1 give you percentages per bend thinning and b31.3 not give them as seen in table 102.4.5 of b31.1?

What basis are you using to state that the pipe is getting thinner faster than the allowed thickness changes?

Thanks for your reply.. " B31.3 is giving you the minimum thickness after bending." I agree to this statement fully. I just do not understand why you have to worry about the thinning from bending due to that as you bend the straight pipe you are exposing more area for the pressure force to act...

I was hoping to gain some insight regarding the following issue. In that calculation of minimum wall thickness per b31.3, I know that you can use the formula in section 304.1.1 for a straight pipe. My confusion comes in when you calculate the wall thickness for example a 6D pipe bend. I see...