Fillet Welding on shell of Propane/ Butane Spheres for Pipe supports

[JSarkar]

I am struggling on an unique situation.
There are spheres which are U stamped almost 30 years old, on which fillet welding needs to be performed to put reinforcement pads to take out some pipe supports later. My question is, has it been done anywhere in the world? I know as per ASME, it is allowed. However does anyone has prior experience on this?

Experts opinion please!!

 

[nickelkid]

If you are welding on the sphere you will need a R stamp. I am having trouble understanding the location of the weld...

 

[metengr]

There are two aspects to this activity. First is to make sure that a design review is performed to properly size and locate the pads using ASME Section VIII, Div 1 requirements. Second, I would agree that a repair organization in possession of a National Board R-Certificate is highly recommended or required (based on local Jurisdictional requirements) to perform this activity.

 

[JSarkar]

Thanks @nickelkid - the pads would be put non-PWHTed petals. won't be near to nozzles

Thanks @metengr - design review has been performed by doing FEA. On query to second, do you recommend to engage same organization who did the U-Stamp? Note that the storage spheres are 30 years old. However every 10 years inspections are performed and didnt reveal anything surprising. Everything is well within corrosion allowance.

Has it been performed this kind of activity anywhere in the world? I know there are plenty of columns, pressure vessels where such kind of revamp works are done. But I personally haven't heard of anything done on storage spheres. Therefore needed help from experts.

 

[metengr]

Yes, I have heard of weld repairs on storage vessels you described. I would use an organization in possession of an R Certificate. Having a U stamp is for new construction.

 

[chicopee]

Get a copy of a current National Board Inspection Code (NBIC) and the chapter that deals with repairs and alterations for guidance. I am not sure if the work that you are considering is regarded as repair or alteration so you will need to clarify with local jurisdiction inspector or the NBoB&PV Inspectors.

 

[JSarkar]

@metengr - Thanks..However my client is looking for references to build up case to management. Appreciate if you have any.

@chicopee - Thanks. As per my R-stamp inspectors, it would be called as alteration since its addition of Reinforcement Pads (and not any repair).

 

[chicopee]

Than as an alteration, you'll need a partial manufacturers data sheet filled out by a registered PE experienced in the ASME code and a signed copy sent to the NB as it already has the original copy. Follow the NBIC on alterations for further details.

 

[MJCronin]

Can you give us some sketches or photographs of what you propose to do ??

Do you plan on rounding the corners of the reinforcing pads that you plan to attach ?

MJCronin
Sr. Process Engineer

 

[JSarkar]

@chicopee - Thanks. protocol would be followed

@MJCronin - I have attached 3D model of some of the vessels. I think these kind of welding won't call for PWHT. [URL unfurl="true"]https://res.cloudinary.com/engineering-com/image/upload/v1458461257/tips/Light_Naphtha_qhbdvc.pdf[/url]

&

http://files.engineering.com/getfil...62-497b-bbc7-fa3660e25001&file=Butane_(N).pdf