Circumferential weld on tank annular plate
Circumferential weld on tank annular plate
(OP)
Is circumferential welding on outside of tank annular plate is allowed? Means if the outside projection of annular plate is less than specified in API then can a butt welded ring be circumferentially welded to annular plate in order to increase the outside projection.





RE: Circumferential weld on tank annular plate
RE: Circumferential weld on tank annular plate
RE: Circumferential weld on tank annular plate
RE: Circumferential weld on tank annular plate
The bottom plate near the shell gets stressed to some extent in hoop tension, and presumably, this effect becomes more pronounced on a large tank, so it is desirable to keep 3-way laps out of the highly stressed area. The larger the tank is, the more critical I would view this. The minimum chime dimension helps support the shell on a soil foundation, and a greater extension helps make sure you have room to land repads on it. Also, that area is subject to corrosion, which is usually worse at the edge. Note that the required chime is less on App. J tanks, and may be less on App. A tanks as well.
In either case, it is undesirable to build the tank in that way, but also undesirable to do a lot of re-work to fix it, too, as that re-work is going to induce residual stresses and reduce toughness in that area. It becomes a matter of judgment and negotiation.
RE: Circumferential weld on tank annular plate