Interpretation of API650-App.C(C.3.3.3) 2

[farzam]

Dear All

I need to know that based on C.3.3.3 full fillet welds on bottom side of upperdeck is mandatory?

Thank you very much

 

[JoeTank]

Fillet welding of the underside of the upper deck is not required by API-650.

Joe Tank

 

[IFRs]

Except if and where necessary to seal weld the compartments...

 

[JoeTank]

IFR,
I'm afraud we may be confusing farzam here. There are no API rerquirements to fully weld the underside of the upper deck. Yes, I would agree that limited amounts of underside welding may be required to effectively seal around the bulkhead and compartment plates. Also, some the underside welding is reequired adjacent to support legs and other simialr items.

Joe Tank

 

[farzam]

Dear Joe Tank,

If welding of Lap jonits underside of upper deck is not required, how you can seal a compartment to be as liquid tight?some lengths of these lap joints are shared between 2 compartments, and liquid can easily move over from one compartment to adjacent, if welding of lap joint does not complete.

 

[chicopee]

Farzam- do not confuse seal seal welding which is just a superficial weld with fillet welding which coalesces weld metal with parent metal to give strength to the joint.

 

[JoeTank]

farzam,
I concur that a limited amount of seal welding of the underside lap joint may be necessary to make the compartments leak tight at the compartment plate. But, nothing is API requires the entire underside to be welded. The detail for underside welding at the bulkhead and compartment plates is now standard practice for these roofs. You could politely suggest that the contractor contact someone that has that type of experience. It does not involve the use of additional plates added for sealing purposes.

Joe Tank

 

[IFRs]

What I remember seeing is the lap cut away at the bulkhead so the plate is essentially butt welded over the bulkhead and the lap starts up again a few inches past the bulkhead on both sides. A fabricator skilled in the art can show you how it's done.