UW-20 tube to tubesheet joint strength ASME VIII Div.1 Ed. 2023

[pvros]

Dear All,
with new code edition, tube to tubesheet joint requirements have been unformed between div.1 and div.2

I have couple of question on code interpretation. May you help me?

UW-20.1.1 (d) - for U tube is not necessary to calculate joint strength

UW-20.3.1 - "...These rules apply to welded only joints and welded and expanded joints in which the strength of the expansion is not considered..."

What is your interpretation? It means that every time I reduce tubesheet thickness considering the tubes expanded, I cannot use UW-20.3 to calculate the tube to tubesheet joint and i am forced to perform mechanical tests as per UW-20.4?
What is the reason in your opinion?
And why I can give credit to expansion to reduce tubesheet thickness for u-bend without any check/requirements (UW-20.1.1 (d)) and why not in this case?

Summarizing my interpretation of changes, in case of straight tube heat exchanger, if in calculation you consider the tubes expansion to decrease required tubesheet thickness, you shall ensure joint strength only as per UW-20.4.

 

[mehdiza]

Dear pvros,
I just received ASME 2023. It seems that for u-tube exchangers there are no link to Lmax (allowable load joint) in part 4-18 (replaced in liu of UHX in div. 1). So your calc. is not dependent to UW-20 (or actually to part 4-21).

In UW-20.3 it is clearly mentioned that it is for joints that "the strength of the expansion is not considered."- UW-20.3.1
So if in any way expansion of tubes contribute in strength of joint you can't consider this part.
And as I see in UW-20.4 generally you are not forced to perform test but by testing you may increase allowable loads for joints.