Weld calculations for studded flange on circular cover

[timsch]

I have a 40" blind flange, 3" thick that will have a 5.5" diameter hole bored offcenter, with a 4" studded flange welded over that hole with a 3/4" inner fillet and a 9/16" outer fillet securing the studded flange. Design conditions are 150psi internal pressure & 320F, all materials 316L.

I have been tasked with performing weld calculations. I am referring to UG-37,-40,-41 & UW-15,-16 and following L-7.4 as the closest example I could find.

I was able to find some information on a studded flange for this calculation in Fig. UG-40(a-1), but I am uncertain about certain values to use for calculations, specifically values for A_2 shown in Fig. UG-37.1.

Per UG-40(a-1), t_n=0. For A_2 = 5*(t_n-t_rn)*f_r2*t, I will wind up with a negative number if I have any value for t_rn. If I just consider the cross sectional area of the studded flange itself, based on the hatched section of Fig UG-37.1, I come up with around 50 in^2, but this is not how the area is calculated per formulas for A_2.

What am I missing?

Thanks,
Tim


EDIT: To answer my own question, I am (was) missing UG-37(b)(2), and I've been barking up the wrong tree. UG-39 does not mention weld reinforcement. I just need to find the section in the code that covers weld calculations for my application

 

[timsch]

UW-16(a)(2) refers to calculations required in UW-15. UW-15(a) refers to UG-41 calculations, which puts me back where I was when I posted above, needing to find A_2.

So, again, what am I missing?

 

[SnTMan]

What you're missing is that A2 is excess area in the nozzle wall available for reinforcement. No wall (tn = 0), no A2 (A2 = 0). Likewise ignore A3, A41 & A43, they're not there. Use A1, A5 and A42.

Your weld strength paths should look something like the attached.

Regards,

Mike

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

 

[timsch]

Thanks for the response, Mike. I was going down that path when I posted right after the 1st (deleted post), but started 2nd guessing myself.

I've attached a drawing of my flange assembly, since it differs slightly from your attachment.

If I use A1, A5, & A42, it appears that I miss out on one of my welds. Is that not so?

 

[SnTMan]

timsch, my mistake, A43 should not be ignored. Inward weld is there.

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

 

[timsch]

The weld path calculations confuse me. Looking at Fig. UG-41(b), W1-1 accounts for A41 & A42, whereas the line 1-1 only goes through one weld. W2-2 accounts for A41 only, yet the 2-2 line goes through only one weld as well.

 

[SnTMan]

timsch, I'd use weld paths as follows: W = (A - A1) * Sv as shown, Fig UG-41.1(b)
W1-1 = (A5 + A42) * Sv, A2 & A41 = zero.
W2-2 = (A42 + A43) * Sv, A2 = zero.

I'll admit, UG-41 is not my best thing

Regards,

Mike

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

 

[timsch]

Thanks again for the input, Mike. I'll look at it with a fresh mind this weekend.