Design Strength, Fd as per UW-20.2 (b) for partial strength weld 1

[cak4Engg]

Dear All,

I was trying to understand the code requirement for a welded tube to tube sheet joint.
Then I stumbled upon a term in UW-20.2 (b), "design strength for partial strength joint".

As per my limited code knowledge, code does not specifically say how to calculate this term.
Code says

​

"design strength is based on the mechanical
and thermal axial tube loads (in either direction) that
are determined from the actual design conditions."

Now Can somebody explain how the value of Design Strength (Fd) is calculated for partial strength weld?
A sample calculation would be very appreciated.

I have also looked into PTB-4 hoping that I would find some guidance, but in PTB-4, Example 4.20.2  says

"Design Strength, Fd: Based on anticipated mechanical and thermal axial tube loads"

Again, I am not able to find any reference on how to "anticipate".

Thanking you all in advance for the support.

 

[SnTMan]

cak4Engg, one way: Part UHX calculations contain calculated tube-tubesheet joint loads for some kinds of shell & tube heat exchangers.

Otherwise, one must determine these loads as per the language you quoted by various methods. Can be messy.

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[cak4Engg]

Dear Mike,

Thanks for the response..
Request you to share any such methods if available...

 

[SnTMan]

cak4Engg, I have no formal methods available. Simple cases might consider hydrostatic loads, and / or thermal expansion / contraction, or combinations thereof. Devil is in the details.

Or arbitrarily select some fraction of the tube strength.

The problem with sloppy work is that the supply FAR EXCEEDS the demand