appendix 13 issue 1

[Tj01]

Hi,
I am currently verifying design of HE based on Appendix 13 and 13-14(external pressure check) I have literally problem to understand terms used in this appendix. The HE cross section is same as figure 8. And i am very much confused with the terms like "inside length of long side of rectangular vessel" and many other. Can any one help me to understand the terms with pictures??? I am more looking for dimensional related terms...Thanks in advance....

 

[gr2vessels]

Imagine a long box with 6 sides;- the box is made of plate with a given thickness. The box has inside dimensions and outside dimensions, taking the thickness in account.
The box has an outside length and an inside length, by substracting the end plates thickness from the outside dimension. Assuming the cross section is not square, then you will have one side of the cross section longer than the other one. Conversely, the longer side will have an outside dimension and an inside dimension, also the shortest side will have an inside and an outside dimension.
Phew..! Now it's getting complicated, if considering the internal and/or external radius of the sides joint. I'll get back with this next week, I have to recover over the weekend...
Cheers,
gr2vessels

 

[BigTank]

I was confused at first by the terminology surrounding 'box headers' as we call them in our shop.

Just to add to gr2's description: The sketches given in those appendices are the cross-section of the header of the exchanger, taken in the plane perpendicular to the tubesheet and/or plugsheet (the side across from the tubesheet-it doesn't always have plugs in it).

The endplates will be those plates parallel to the plane of viewing for these cross-sections. That is, of the 6 plates that would make up a rectangular box header, the end plates are usually the smallest in dimension (and thus thinnest).

The code's use of long and short side plates as a nomenclature can be misleading. This is a poor choice of words in my opinion. Sometimes the cross section can reverse this, and the long-side plates are 'shorter' in the dimension of concern than the short-side plates, reversing the long and short sides in reality relative to their nomenclature.

My eyes have gone crossed...am I helping or hurting?

Just remember what it is that you're trying to calculate: bending stress and corner stress. Remember the reality of what the pressure will do when looking at the stress equation you are considering. This might expose some of the motivation of this part of the code and clear up your confusion.

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