API 653 Lap Patch Hole Size

[iangineer]

API 653 sec 9.3.2.1 states that minimum hole diameter for use of lap patch is 2". Do you all agree that if I have a 1/2" corroded hole, that it would need to be cut/drilled out to 2" diameter for a lap patch to be used?

 

[HTURKAK]

TRUE!!

9.3.2.1 The welding shall be continuous on the outer perimeter of the repair plate and the inner perimeter of the hole
in the shell plate. The minimum hole diameter is 2 in. Shell openings due to plate removal shall have a minimum
corner radius of 2 in.

Pls look Figure 9.1— Acceptable Details for Replacement of Shell Plate Material for weld spacing requirements etc..

 

[iangineer]

@HTURKAK, I forgot to thank you for your response. Thank you!

 

[IFRs]

How thick is the shell plate? Have you checked the lap patch thickness using the appropriate lap joint efficiency? You might need a butt patch...