enginerd74
Mechanical
- Oct 17, 2007
- 5
A few questions for the group. Thanks for any time you may be able to spend on them.
I have a piping system that was designed and registered using ASA B31.3, with Chemico design specifications. The service conditions are:
-10" Sch40S A358 TP304 c/w TP316 300# flanges
~25000scfm NOx
-510C
-110psig
Questions:
1. Am I obligated to replace and rebuild lines to the standard of the day, or can I use the newest ASME codes? How might I find a copy of the codes that may have been used in 1966.
2. I am wondering how best to specify an equivelent material. Digging into what is available, I am finding it difficult to find standard grade 304 that is not dual certified (low carbon), and am worried about thermal fatigue, creep and any other (?) high temperature failures that may occur with replacement of the dual grade. My question is, would it be prudent to specify 304H as an alternative to add higher resistance to high temperature failures, and comply better with the original intention of the straight TP304 grade specification?
3. Would the A358 standard (no sub class specified) of 1966 be similar to todays Section II A358 specification?
4. I would also like to investigate the possible change from A358 to A312 seamless designation. I would conduct any pressure calculations required to ensure that we meet code. Any warning bells with a switch from the original specification?
5. The original design calls for mixing b/w 304 and 316 pipe and flanges for differing pipe diameters. Would this have been for economical, material availabilty or other reasons of the day? I will begin researching if 316 flanges would have higher strength at the higher temperatures to match design conditions.
Thanks for the time.
I have a piping system that was designed and registered using ASA B31.3, with Chemico design specifications. The service conditions are:
-10" Sch40S A358 TP304 c/w TP316 300# flanges
~25000scfm NOx
-510C
-110psig
Questions:
1. Am I obligated to replace and rebuild lines to the standard of the day, or can I use the newest ASME codes? How might I find a copy of the codes that may have been used in 1966.
2. I am wondering how best to specify an equivelent material. Digging into what is available, I am finding it difficult to find standard grade 304 that is not dual certified (low carbon), and am worried about thermal fatigue, creep and any other (?) high temperature failures that may occur with replacement of the dual grade. My question is, would it be prudent to specify 304H as an alternative to add higher resistance to high temperature failures, and comply better with the original intention of the straight TP304 grade specification?
3. Would the A358 standard (no sub class specified) of 1966 be similar to todays Section II A358 specification?
4. I would also like to investigate the possible change from A358 to A312 seamless designation. I would conduct any pressure calculations required to ensure that we meet code. Any warning bells with a switch from the original specification?
5. The original design calls for mixing b/w 304 and 316 pipe and flanges for differing pipe diameters. Would this have been for economical, material availabilty or other reasons of the day? I will begin researching if 316 flanges would have higher strength at the higher temperatures to match design conditions.
Thanks for the time.
I can say that the code issues are set by your local authorities having jurisdiction or the laws of your state/province (you didn't say where you were located). They will tell you. In Kalifornia, it is Title 8 and the CBC. Your (or the owner's) insurance carrier will also have something to say about this. If they are self-insured, then you look at the law (which the insurance carrier does as a minimum case anyway).