ASME VIII Div1.Cone/cylinder intersections
ASME VIII Div1.Cone/cylinder intersections
(OP)
Hi all,
I have a kettle type heat exhanger-TEMA AKL.The tubesheets are both fixed tubesheets.The tubesheets are welded directly to the conical part of the shell, using a hub of minimum dimensions(lets say 25 mm).Per ASME VIII, Div.1, Appendix 1, the small end of the cone (at the cone/tubesheet junction) needs to be reinforced.Assume that the limiting distance of reinforcement [sqrt(Rsts)] is GREATER than 25 mm.May I take into consideration the area available in the tubesheet hub in order to reinforce the junction (obviously also reducing the length available to 25 mm) OR should I ignore this area in the hub? The obvious answer is to ignore the area available in the hub as this would be the more conservative approach, however, the reason for asking the question is that ignoring the area in the hub necessitates a substantial increase in cone section thickness to reinforce the junction.The exchanger is stainless steel, so obviously there are also price implications involved.I'd appreciate any thoughts (based on Code/TEMA considerations).Please do not refer to ASME new Appendix UHX (the exchanger was designed to an earlier Code edition).
Thanks.
John
I have a kettle type heat exhanger-TEMA AKL.The tubesheets are both fixed tubesheets.The tubesheets are welded directly to the conical part of the shell, using a hub of minimum dimensions(lets say 25 mm).Per ASME VIII, Div.1, Appendix 1, the small end of the cone (at the cone/tubesheet junction) needs to be reinforced.Assume that the limiting distance of reinforcement [sqrt(Rsts)] is GREATER than 25 mm.May I take into consideration the area available in the tubesheet hub in order to reinforce the junction (obviously also reducing the length available to 25 mm) OR should I ignore this area in the hub? The obvious answer is to ignore the area available in the hub as this would be the more conservative approach, however, the reason for asking the question is that ignoring the area in the hub necessitates a substantial increase in cone section thickness to reinforce the junction.The exchanger is stainless steel, so obviously there are also price implications involved.I'd appreciate any thoughts (based on Code/TEMA considerations).Please do not refer to ASME new Appendix UHX (the exchanger was designed to an earlier Code edition).
Thanks.
John





RE: ASME VIII Div1.Cone/cylinder intersections
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RE: ASME VIII Div1.Cone/cylinder intersections
Steve Braune
Tank Industry Consultants
www.tankindustry.com
RE: ASME VIII Div1.Cone/cylinder intersections
you are quite correct, the reinforcement rules do indeed apply to the intersection of the cone / cylinder.However,
in my opinion, the "hub" would be considered a cylinder because at the junction,it would be subject to stress due to the internal pressure [no mention is made of a "minimum" cylinder length - except where the minimum reinforcement length is calculated as sqrt(Rs ts)] . Thus, I think that the Code Appendix 1 rules for reinforcement of the junction would apply.Comments please.
John