Finned Tubes per SB359

[Tomtation]

Dear Fellow Members

I am trying to determine why both SB359 and SB75 are listed in Section IIA. Per UG-8(b), I can make integrally finned tubes using any material listed in Section IIA. The allowable stress values for SB359-H55 is substantially lower than SB75-H55. Does anyone know the reason for the difference?

Thanks

 

[GenB]

finned tube mfr? 'sorry I ask
what do you know about cupronickel HW boiler tubes?
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