ASME Section VIII Appendix 9 Clarification

[Jordan123]

I'm trying to check some type 4 jacketed vessel with closure bars calculations (f-1 attached to shell, g-3 attached to jacket).
I'm not clear on some of the values in the formula for calculating jacket space, j, given in (c)5 of Mandatory Appendix 9. The definition of symbols given don't make it clear to me.
1) Is S the maximum allowable stress for the jacket or shell?
2) Are tj and ts the true norminal thickness of the jacket and shell or the nominal thickness minus the corrosion allowances?

 

[MitchYurko]

Jordan,

j is the jacket inside radius minus the shell outside radius. These are shown in the Fig. 9-5 sketches as Rj and Rs respectively.

1) S is the max allowable stress per Sec. II part D for the jacket material.

2) I'm assuming tj and ts are the nominal thicknesses without the corrosion allowance. Someone either verify this or correct me.

Hope this helps!

Sincerely,

Mitch Yurkovich

 

[prex]

1)As we are determining the thickness of the closure bar here, S is clearly the allowable stress of the closure bar.
2)t[sub]j[/sub] and t[sub]s[/sub] are actual thicknesses as per code, therefore they are in the corroded state; BTW all other dimensions (R[sub]j[/sub]) should also be in the corroded state. I don't think that in the new state the formula for j would give a lower value, but, if that was the case, you could safely use this lower value, that shouldn't make a sensible difference.
And notice that the so calculated j is a maximum allowable, you should use the actual value when calculating t[sub]rc[/sub]

prex

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[Jordan123]

Thanks so much for your help prex; exactly the clarification I was looking for.