minimum size of reinforcing pads on pipe connections

[socrate1980]

good morning

what is the minimum size of reinforcing pads?

so I need reinforcing pad not to withstand pressure at intersections but to lower SIF of the intersection.

(low pressure big bore pipes with thickness just bit above 100 times pipe diameter, 15 mm thk 1320 mm DIA)

it is also a crowded pipe collector full of branches.

I would usually put external radius of pad equal to diameter of branch but space is not enough.

thank you for any suggestion.

 

[LittleInch]

What code?

Branch reinforcement size is detailed in ASME B31.3 AND B31.4

Or use "weldolets?"

So you have pipes within 1D of each other?

Might need a special strip of extra material in that case. so like curved cricket bat.

Drawings help immensely.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[mk3223]

May refer to B31.3 Section 304.3.3 for the reinforcement requirement of the welded connections.
Depending on the branch size, typical weldolet and sockolet fittings may be adequate for the piping branches construction.

 

[KevinNZ]

As you say the pad is not required for pressure and you only want to reduce the SIF. Refer to B31J calculations and see where changing the dimensions as the desired. effect. FEA (NozzlePro) can look more options.

 

[socrate1980]

good morning guys

thank already you for replies

pipe is big bore 52" and connections are 32" very near to each other (something like 300 mm external side to external side).

I can choose thickness between 10 and 15 mm even if minimum thickness is just 1 mm beacause pipes go to very low pressure (1,5 time atmospheric).

weldolets are too long to order and i dont even know if there are on 32" size.

thank you all still, much appreciated.

for stress analysis i am using B31.1 but I am not compelled by client (whatever is technically justifiable is ok for my client).

thank you

 

[LittleInch]

What sort of connection are you looking at? got a drawing of the connection?

So full thickness weld for a contoured 32" pipe or a stab in fillet weld?
All the B31 codes do similar branch connection designs.

At that size and thickness and proximity of one to the next I would be amazed if your header didn't start to bend and bow like a banana.

If you want more strength to the weld then I would just weld on a curved plate ID the same as the OD which covered the whole length of these massive branches. but suspect you'll need to do some FEA to show if it works or not and that reference by Kevin NZ looks good.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[Piper Mike]

Socrate1980

Your design sounds like mechanical reinforcement for a stub-on branch connection.
A donut ring pad should suffice your needs, start with 4" wide and see.
The B31.3 guideline for the pad and weld profile is easy to calc out by hand if your not on a network. You can play with thickness and weld size.

Good luck
Mike