Electric Immerison Heater (Appendix 41)

[SG12345]

I have a question regarding the Appendix 41 analysis in ASME Section VIII, Div.1. I recently ran an analysis for a 8" 300# B16.5 SA 105 heater flange with holes drilled in it. I wanted to find out what the MAWP of the heater flange was going to be. It turns out that the MAWP of the heater flange based on the Appendix 41 analysis is higher than that of a 8" 300# B16.5 pristine (no element holes) blind flange. The allowable stress per Appendix 41 for bending is 2xS which would appear to explain why the heater flange can surpass the B16.5 pressure rating. Does the analysis of Appendix 41 supersede B16.5 pressure ratings? I think the answer s yes. Just wondering if anyone else has run into this issue.

 

[jamesl]

It is pretty clear in 41-6.4 that B16.5 pressure temperature rating does not apply if calculation is done per Appendix 41. Note Div1 code use 1.5S as bending allowable in UG-34, too.

 

[SG12345]

Thanks Jamesl. I suspected this as well.