Shell to floor weld size?

[LurmClaxton]

I am very aware of the maximum allowable sizes of shell to floor weld in various storage tanks, both with annular welds and those with sketch plate floors. I'm also aware of the differences between the relevant codes BS2654, 650 etc.

My question is about the implications of having a very over sized shell to floor fillet weld, say 3/4"+ (19mm) on a small tank with 1/4"(6.4mm) lower shell and sketch plate floor.

Obviously there is a size restriction for a reason and I know that this weld plays a big part in the stress distribution of the lower shell.

Is there a risk of cracking and catastrophic failure with an over sized shell to floor fillet weld.

Any thoughts much appreciated.

 

[Duwe6]

Assuming that the material-of-construction is 'mild' carbon steel, I don't see any risk on a small tank.
Reasoning; 1 - tank is small, thus stress on corner weld will not be very much. 2 - most of the weld beads have been stress-relieved by the outer weld layers [think 'temper bead' technique], so the bulk of the unrelieved stress resides in the outermost layers, and they should have relieved themselves by weld distortion of the chime extension on the OD, and 'humping' the sketch plate on the ID.