Requirements on Column w/Seal Welded Trays

[PVdesigner]

Would anyone please shed some light on minimum design considerations required on vessel with seal welded trays?
Situation: One of the tower has four (4) wash trays (bubble cap, classified as critical service trays, ) at the top section. To meet the leakage test requirement of 1” of water in 5 minutes during field testing of trays, as specified on specification, trays require seal welding of panel to support ring and also panel to panel per tray vendor, and I have never come across this situation before. If trays are seal welded to the support ring and also the abutting panels, how can inspection be done once vessel comes in operation as these trays literally creates 5 different isolated chambers as chimney tray does without any access to them. I believe that these trays will have to be discarded whenever the trays are dismantled for vessel. Thank You

 

[gr2vessels]

PVdesigner,
It sounds kind of bad joke or a bad translation from chinese. The seal weld of the tray to the support ring can only performed from underneath of tray, but the abuting panels should have raised flanges, which can only be seal welded from above the tray. That means, you need access from top and bottom of these trays. Also, it would be impossible to seal weld the panel edges where they meet at their circumference.
However, if for any reason you need to control the leakage during the testing of those trays, I would think the bottom seal weld would suffice. After tests completed, you only need to grind off each seal weld, removing the trays one by one, starting from the bottom and making your way up to the first tray.
Also, I never heard of creating pressurrized chambers between the bubble trays, but if it is true, I would like to know how's that working.
Cheers,
gr2vessels