API 570 Appendix C - Repairs

[WelshBoy]

Hi guys,

I would like to know what the length limit (less than half the pipe diameter) for a patch repair is based on? Thank you in advance for your consideration?

Regards Dan

 

[Bonswa]

Note states.....
--Size of the patch should not exceed 1/2 the pipe diameter. A full encirclement sleeve should be used if the corroded area exceeds 1/2 the diameter.--

My guess would be for structural support. The fact, that it jumps from a patch that's 1/2 the diameter all the way to a full sleeve, leads me to believe that the structural integrity needs to be accounted for.