Groove weld gap for re-pad
Groove weld gap for re-pad
(OP)
All,
As attached sketch, to consider combined thickness of (shell + pad) to check the local stress at the trunnion junction, what will be the groove weld gap as shown related to shell, pad or trunnion thickness?
As attached sketch, to consider combined thickness of (shell + pad) to check the local stress at the trunnion junction, what will be the groove weld gap as shown related to shell, pad or trunnion thickness?





RE: Groove weld gap for re-pad
Regards,
Mike
The problem with sloppy work is that the supply FAR EXCEEDS the demand
RE: Groove weld gap for re-pad
RE: Groove weld gap for re-pad
RE: Groove weld gap for re-pad
I also see other company's standard asking the groove gap to be equal to pad thickness, that makes sense such that pad is definitely integral with shell to share the load and the combined thickness can be used in the analysis. What is your experience ?
RE: Groove weld gap for re-pad
Exactly - Full-Penn the trunnion, then lower the repad and weld it into the OD trunnion weld. Look at the repad detail dwgs for API 650 nozzle repads.
RE: Groove weld gap for re-pad
RE: Groove weld gap for re-pad
RE: Groove weld gap for re-pad
The idea of a repad is to distribute the concentrated loading/stresses to a larger area of the shell. So, why would you work so hard to concentrate the stresses at the root of the trunnion, with a kinda trashy, unsymmetrical weld and repad detail? The proportions of your sketch seem to indicate excessive welding, which can be almost as bad as too little weld or an unsymmetrical detail. The weld btwn. the shell and trunnion does not have to be a full pen. groove weld if the loads and stresses do not req’r. it. But, it should be well detailed, well done, and defect free, becuase of the high loads it may see, the out-of-plane loading it may see, and the potential of impact loading during lifting. I would weld the trunnion groove to the shell without any appreciable reinforcement fillets, as mentioned above. Then slip the slotted repad over the trunnion, with a partial pen. groove bevel on the slot which would distribute 50-60-70% of the trunnion design load, how conservative do you need to be? The intent being to distribute some %age of the load further out into the shell. Then fill the groove btwn. the trunnion and the replate, and add a reinforcing fillet on the top of that, and a fillet all around btwn. the repad and the tank shell. Do a good job of welding the root pass of this groove weld. Round the corners of the repad so those fillets can more likely be clean continuos welds. The most critical weld location is at the corners of the plate edges on the trunnion, where welding around those four corners tends to cause a stress raiser, an undercut, right at the corner and the toe of the fillet. The easiest fix for this is to grind a slight radius of the trunnion plate edge/corners where the fillet wraps around the corner, this tends to prevent the weld puddle from sloughing down at the sharp edge/corner.
RE: Groove weld gap for re-pad