Vertical shell joint 5t offset

[kdgran]

Section 5.1.5.2 states an offset of 5t is required between adjacent shell courses. Does API allow this 5t offset requirement to be eliminated if the shell courses are shop welded.

We fabicate many SS vessels. We will purchase 48" wide sheets and shop weld the sheets together to create a 96" wide sheet for field installation. I had heard through the grapevine that API had modified this 5t requirement for certain thicknesses but I haven't been able to find anything to back up that claim.

 

[Duwe6]

Not that I know of. It isn't that much really: for T=1/4, 1-1/4" offset. for T=1/2, 2-1/2" offset. No reputable shop would want their vertical seams any closer togather than that. Usual offset is either 1-2 ft, or staggered by half the plate length.

You can always seam your sheets into 96" wide plates and then notch both ends about 6" to stagger your verts. You would only loose 6" per sheet length. Might make everybody happy.

 

[kdgran]

I spoke with a gentlemen on the API commitee and the section in question is S.4.11.3. This section was added on addendum 1 but left out of the latest addendum. This section lets users weld SS plates together in the shop and elliminate the offset requirement for the shop joints up to 1/2" thick.

 

[Soln]

I noticed that the section allowing shop welded 4 way seams disappeared- mistake? Or did API rethink allowing it?