External Pressure Stiffner Ring

[leon_har_dt]

Dear All,
i hope you are doing Ok,
one constructive and code question.
Can be a stiffner ring be attached by welding above a groove shell joint? (as mention in the image)


I read UG-30, and it doesn't mention or doesn't restrict to do it
Why to do it? I'm validating a design of a HX with a reducer cone. for 1-8 the ring has to be situated within a calculated distance.

I'll appreciate any answer

Thanks!

L.

 

[Trestala]

It is not advisable. You can just increase the conical thickness or apply a thicker knuckle transition.
Are you applying PWHT on the equipment and what is the material?

 

[r6155]

RT 100% the butt weld and 100% PT the fillet weld.
More information is required to confirm the above: general dimensions, service, material, design pressure / temperature.

 

[leon_har_dt]

Thanks a lot for your answer.
Yeah, i thought about knuckle but i face manufacturing limitations from were we cosntruct.
Nice to here r6155, fortunately this is a 100% RT equipment.

It's seemed odd to me and didnt find any code discrepancy so I preferred to ask

Thanks a lot again.

L.

 

[jt1234]

Yes it is acceptable. There is no restriction any attachment can not be welded on top of weld. It is just personal preference not to do that as afraid of not able to NDE the butt weld or higher stress riser in the welding zone. But nothing wrong.

 

[SD12]

Dear All,
i hope you are doing Ok,
one constructive and code question.
Can be a stiffner ring be attached by welding above a groove shell joint? (as mention in the image)
View attachment 14493

I read UG-30, and it doesn't mention or doesn't restrict to do it
Why to do it? I'm validating a design of a HX with a reducer cone. for 1-8 the ring has to be situated within a calculated distance.

I'll appreciate any answer

Thanks!

L.

Hello.

You should never weld anything on the governing welds. There must be a distance between the center line of the butt weld and the next structural element (nozzle, ring, stiffener and so on).

 

[jt1234]

Disagreed, It is just personal preference either by personal preferred "distance", or written in specific company's vessel spec talking about how far away, 2", 3", 2t, 3t, etc., no universal guideline. There is no prohibit to not welding attachment on top of weld. Period.

 

[SD12]

Disagreed, It is just personal preference either by personal preferred "distance", or written in specific company's vessel spec talking about how far away, 2", 3", 2t, 3t, etc., no universal guideline. There is no prohibit to not welding attachment on top of weld. Period.

Well, if fatigue is the issue, you shouldn't weld anything on top of the governing weld. Such complex weldment detail creates stress discontinuities that is difficult to analyse.

 

[CuMo]

It is very rare that the code calculations for the stiffening ring position line perfectly with what you can do in reality.
My approach would be to overdesign the size of the stiffening ring and place it as close as possible to where it needs to be.

 

[r6155]

Be careful
(OP) only refers to external pressure. E=1 without RT.
100% RT does not guarantee the absence of leaks.
100% RT does not replace leak testing.