Nozzle Pipe Cap to Reinforcement Plate to Nozzle Pipe UG-34 Clarification

[caper656]

Hey everyone,

My customer is requesting a specific Hydrotest Nozzle Pipe with PipeCap and reinforcement plate. They are specifying welding and material thickness inwhich I need to verify since this is an ASME pressure vessel. see below link for a visual.
Link

Nozzle Pipe Cap: SA234, 6" XH (0.438" wall thickness)
Pressure: 200 PSI for hydro of 1.3*200= 277 PSI
Nozzle Pipe: 4" 0.337" Sch 80 SA-106B Pipe
Reinforcement plate: 1/2"thk circular plate. OD: 7.25" that has a 4.5" ID to allow the pipe to slip in.
Weld joint per the customer's request is 1/4" Fillet weld for both joints

My main question is what is the best way to calculate the Fillet weld joint size of both the plate to pipe and the pipe cap to plate.
I was thinking, UG-34e for the plate to nozzle pipe but it shows a double weld in the figure.. wondering if I can just use 0.7ts or if i need to use 2 X 0.7ts for single outside fillet. what guidance can you guys provide? thanks!

The pipe cap thickness will be per ASME B16.5 or I can use thickness based on the nozzle pipe calculations.
The Nozzle Pipe would be per ASME UG-27c2 (required thickness would be 0.0299" thk)

For the plates thickness, i was thinking of UG-34 t=d*SQ(CP/SE) where C would be 0.6 since I have no NDE. Ive been told I can take assumption for 0.85 but i have yet to see where I could via ASME. Using C=0.6, i am only needing 0.296648" thick plate.

 

[SnTMan]

caper656, strictly speaking these temporaty closures are not subject to the usual Code rules that apply to the vessel itself. Therefore they only need be designed per good engineering practice. Welds can be sized per a strength-of-materials approach and a suitable allowable stress which may be as per Code allowable or somewhat higher even up to 90% yield if you wish.

Your description of weld details is not clear. I can see the ring being fillet welded to the pipe neck, but then a fillet weld of cap-to-ring is hard to picture. Groove weld maybe?

I don't see UG-34 as being particularily applicable. It's a ring, not a head (BTW I think you meant E = 0.6, not C. Doesn't apply in any case as it is a fillet weld, not a butt-weld). I'd design the ring for shear stress only, perhaps at the cap OD. (0.296648"? Really?)

Don't make it too hard.

Regards,

Mike









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

 

[caper656]

interesting perspective and i do remember using that that principle of temp fixtures on a different application. Thanks for the reminder Mike! after I make the "good practice" calculation, I will verify with the AI.

Weld Size:
Throat Size: x Cos 45deg = .25"thk X (0.707) = 0.177"
Effective Area: QTY Welds X Length X Throat = (1) x (circumference of 4.5"OD nozzle pipe) X (0.177) = 2x14.14x0.177= 2.50 in^2
Using ER70S-6 wire at 70,000psi, solve for F=OtA=(tensile strength of weld)*(Effective Area of weld) = 70,000*5= 175,000 lbf

Plate and Pipe Cap Thickness:
If I cant force UG-34 by calculating a flat head (assuming the pipe cap material area replaces/exceeds the missing ring material--more complex then it needs to be), then i would fall back on something simple like Circular Plate, uniform load, edges fixed equation...
Stress at the Edge

Om= 3pr^2/4t^2 = 1970psi and Max Displacement @ r=0 is pr^4/64D = 0.00024in​

what do you think?

(and correct, i meant E=0.6 per UW-12 as a single fillet without backing strip.

 

[SnTMan]

caper656, weld sizing looks on the right track, but I get 175,000 per each 1/4" fillet.

Not sure I buy the circular plate logic, but looking at shear thru the thickness of the plate at the nozzle OD gives much the same formulation as the weld sizing, without the throat dimension of course. Hard to formulate anything more exact without fab details, but for your pressure, 1/4" plate would be more than adequate.

Best of luck

Mike

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

 

[caper656]

I was assuming one continuous circular weld but I agree it would be very approximate without calculating the ID and OD of the weld at the pipe cap.

Are you using roark for the shear thru plate calculation at the pipe OD?

 

[SnTMan]

No. Shear area is just nozzles od x pl thickness

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

 

[SnTMan]

Unless load is offset somehow, can,t see bending being a consideration. Pls excuse, on mobile

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