When we have repads on nozzles, we will put a test hole in the repad to allow checking of the vessel(under the repad) for leaks in the vessel.


Is this required for wear plates that lift lugs are attached to, whether on the head or the shell?

Thanks in advance for any comments on this.

Fernandez

The purpose of the repad around the nozzle is to give it strength and tapped hole in it is two-fold as it (1) relieves pressure of air entrapped in the space between the shell & the repad and (2) a pneumatic pressure test will reveal any thru hole discontinuities of the weld joint of the nozzle by visually examining the inside of the nozzle weld with soapy water solution.

I do not believe it is required to have holes for wear plates that lifting lugs are attached to altho our engineers require it on all plates that are completely seal welded.

I am sure some others more knowledgeable will give their advice here.

No, the hole is to avoid any pressure build up in case of leaks on weld nozzle to shell. This is the Code requirement.
Hole may be tapped to screw in a air pipe and make a bubble, soap test to verify there is no leaks on weld nozzle to shell.
The hole in the pad for legs or saddle or lifting lug is required if the pad covers a weld and be treated as the nozzle to shell weld.
Mauro

Altho not VIII, API 650 (3.7.5.1) (8th ed.) states "Manhole reinforcing plates, ...., ..., shall be provided with a 1/4" telltale hole (for the purpose of detecting leakage through the interior welds. Such holes shall be located substantially on the horizontal centerline and shall be open to the atmosphere."

Sec VIII, UG36g, Reinforcing plates and saddles of nozzles attached to the outside of a vessel shall be provided with at least one telltale hole (max size NPS 1/4 DN8) that may be tapped for a preliminary compressed air and soap suds test for tihgtness of the welds that seal off the inside of the vessel."

Lifting lug Pads are provided with a tell tale hole due to these reasons
a) During welding there may be pressure build up between pad and shell
b)The pad may be crosssing a weld seam , in which tell tale hole is required.
c)During rubber lining air trapped between pad & shell will expand and will not allow bonding .

So to avoid all such things , tell tale holes are provided as standard practice. Except for (b) there is no code requirement.