ASME HX - Tubesheet to Shell Weld

[129PAR]

What ASME weld designation would you give the attached weld detail? I have been seeing this type of weld detail often, but cannot find an applicable weld detail in ASME Section VIII. Would this detail fall under UW-13.2 (d)? Thanks for your time.

 

[marty007]

I would say no as the dimension tp is not followed. I do not see this as being an acceptable weld detail.

 

[SnTMan]

I suppose it is possible tp could be considered as inside the shell from the weld to the nearest tubesheet face. But. It is a poor detail.

Regards,

Mike

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

 

[marty007]

If a plate is being used for the tubesheet, then I would ask how the joint is going to meet paragrph UG-93(d)(3). Specifically, how is the peripheral edge of the flat plate going to be reexamined by magnetic particle or liquid penetrant method when it is covered by a shell?

 

[TJOrlowski]

We've seen vessels sent in for rebuild that have integral tubesheets attached in this manner (usually the vessel originates from Europe).

As others have pointed out, it is an inferior joint. We always end up replacing the tubesheet and matching it to the shell OD.

-TJ Orlowski

 

[Afox88]

It is very hard to tell from the picture if it is there, but I have seen welds such as this with a "lantern" ring in the weld such as the attached picture. It is very common for all-welded (non-removable bundle) hairpins exchangers.

 

[SnTMan]

Afox88, new one on me. What is the purposae of the ring?

Regards,

Mike

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

 

[Afox88]

When assembling all-welded hairpin exchangers, most of the time you assemble the bundle fully outside of the shell. When you insert the bundle, the tubesheet has to go through the shell so it must be obviously be smaller in diameter than shell id. You then use the ring to comply with UW-13.2(d) with the thickness and width of the ring being 'tp' and 'a', respectively. I am not sure if it is a valid weld without the ring, but I have not seen this configuration without the ring before.