Pad minimum Radius

[david339933]

Is there a minimum radius for pads attached to a shell of a vessel in ASME Sec VIII Div 1? I couldn't find anything regarding this, besides requiring the tell-tale hole in UG-37. I am thinking the radius must be 3 or 5 times the thickness of the pad? This is not a re-pad, but a pad of similar material as the shell to attach a non similar material. Ex. SA-516-70N Shell, SA-516-70N Pad and 44W welded to the pad.

 

[doct9960]

david,

The ASME Code does not specify a minimum corner radius on repads or, in your case, poison pads. My rule of thumb is 2" minimum, or 3" if the pad is the same thickness as the shell.

What is the intended purpose of the 44W structural steel? I'm just curious because you have a normalized vessel steel and you have a Canadian structural steel...I'm just assuming the 44W is exposed to low temperature. If it is indeed exposed to low temperature and the 44W is a load-bearing attachment, you might want to consider an impact tested structural steel.

 

[david339933]

44W is a fabricated pocket to fit an HSS member which supports a platform. The pocket will sit on the "poison pad". 44W is used due to availability and of course the almighty $$.

 

[DSB123]

The smaller the radius the greater the stress concentration. Never seen a corner radius less than 50mm for a pad.