Half-pipe jacket

[PVinspector]

Installing a Code (U stamped) half-pipe jacket on the outside of a vessel. What part of Section VIII-1 determines the weld along the two sides of the half-pipe? Can it be fillet only, or does it need to be beveled? There are lots of sections that could apply, Appendix EE is there too.

Anybody familiar with the half pipe jacket constructin to Code?

 

[JohnBreen]

Title Background of the half-pipe jacket rules in Section VIII, Division 1

Author Jawad, M.H. (Nooter Corp., St. Louis, MO (United States))

Publication Date 1994 Aug 01

Other Number(s) ISSN0094-9930; CODEN: JPVTAS
Resource Type Journal Article
Resource Relation Journal of Pressure Vessel Technology ; Vol/Issue: 116:3
Subject 420200 -- Engineering-- Facilities, Equipment, & Techniques; JACKETS-- DESIGN;PIPES-- JACKETS;

Description/Abstract Rules for the design of half-pipe jackets were developed by the ASME Subgroup on Design of Section VIII. This article gives the background information for the derivation and various assumptions made in developing the rules.

 

[JohnBreen]

The Code says fillet weld.

cstools.asme.org/csconnect/pdf/R6636.pdf

 

[PVinspector]

Thanks John, that was very helpful.

 

[doct9960]

PVinspector,

What's the fluid in the jacket? Will the jacket be in cyclic service? If in cyclic service, I would follow the nonmandatory guidance in Appendix EE...through-thickness weld plus fillet weld.

Also have a look at this thread292-12586 for more discussions on half pipe jacket welding.

 

[PVinspector]

Don't know any of the service particulars, I just told him I would try to find the proper Code rules. I will pass it on and he can decide. 3" stainless sch. 10 half pipe my guess is it will end up fillet only. I think it is 100 psi MAWP.

 

[MJCronin]

My two cents....

My experience with fabricators has been that the purchaser can specify either fillet welds or full-penetration welds with fillet backing.

The cost difference is typically large, and it is very difficult to perform "full penn" welds on smaller half-pipe configurations (~2"NPS and smaller)

I have found the kind and knowledgable people at ROBEN MFG to be a worthwhile asset and have discussed this very issue with them......

http://www.robenmfg.com/projects_halfpipe.html

-MJC

 

[vesselfab]

What Mr. Cronin said

Full penetration welding is very difficult with a tight pitch between pipes.

This is why we have not built one of these in 20 years.