B75/B359 C12200 Finned Tube
B75/B359 C12200 Finned Tube
(OP)
A manufacturer says his finned tube is "produced in alloy C12200 to meet mechanical, chemical, and testing requirements of ASTM B75/B359".
If I want to do Sect VIII Div 1 UG-28 calculations for this tube, do I use the External Pressure Chart NFC-1 or NFC-7 in Sect II Part D? (I am referring to lines 4 & 5 on page 186 of the 2008a addenda of Sect II, Part D.)
Thanks,
Rick
If I want to do Sect VIII Div 1 UG-28 calculations for this tube, do I use the External Pressure Chart NFC-1 or NFC-7 in Sect II Part D? (I am referring to lines 4 & 5 on page 186 of the 2008a addenda of Sect II, Part D.)
Thanks,
Rick





RE: B75/B359 C12200 Finned Tube
Cheers,
gr2vessels
RE: B75/B359 C12200 Finned Tube
I guess what your manufacturer is saying is that he can provide you with 2 classes of finned tubes:
1. tubes with integral fins that meets the requirements of ASTM B359;
2. tubes with non-integral fins where the tubes meet the requirements of ASTM B75.
(If the finned tubes are for ASME VIII-1 construction, the material designation should be ASME SB-359 or SB-75)
For SB-359 Alloy C12200 Temper H55 or O61, use External Pressure Chart NFC-1.
For SB-75 Alloy C12200 Temper O50, use External Pressure Chart NFC-7. If the Temper is H55 or H80, use NFC-6.
(My above reply is based on the 2007 Edition of ASME II Part. I still don't have a copy of the 2008 Addenda. Check your 2008 Addenda and see what it says there.)
RE: B75/B359 C12200 Finned Tube
This is consistent with the guidance provided by the folks who certify our facility. Namely, the UG-27 & UG-28 calculations were developed for simple cylindrical bodies under pressure. Once you start adding fins (which I suppose can either be stiffeners or stress-concentrators) the calculation results lose accuracy, and actual test results become the more reliable method for finding allowable pressure.
All of this is quite interesting, and I am grateful to those who help enlighten me to the many intricacies of the code.
Rick