API 650 Low Type Nozzle 2

[StaticPressure]

Hello Everyone,
I have a 36” man-way close to the floor of an API 650 Tank. As per Fig. 5.8, we need to have a low type re-pad for the man-way, but the manufacturer says an ordinary (circular) re-pad is ok, as long as it provides the reinforcing required as per Para. 5.7.2 and distance between weld joints of re-pad and floor is not less than dimension “C” in Fig. 5.6. My question is whether the low type reinforcing plate as per Fig. 5.8 is used also for increasing the strength of the area between opening and shell to floor connection which is a discontinuity in the cylindrical shell and local bending stresses appear in addition to the normal tensile stresses. I appreciate your responses regarding my concern.

 

[IFRs]

Your manufacturer is correct. The code requires reinforcing and weld spacing. Satisfy that and you are good at least for the present.

 

[JStephen]

The mouse-hole shape repads are used for weld-spacing (and speed-of-welding) reasons, not for additional reinforcing.

 

[IFRs]

Tombstone shaped repads prepare you for much lower costs when you add a secondary bottom, or cut out and replace the bottom. I use them for almost all nozzles regardless of elevation.