API 650 Split Reinforcing Pad

[wescburns]

Hello All,

I have a 72.75" diameter reinforcing pad that is going to be used on a 36" manway for a tank. The design is being carried out per API 650. The problem is that access to the area where the nozzle is being installed is very limited. The hatch leading to the area where the manway is going to be installed is only 4'x18". Therefore my reinforcing pad wil not fit through in its existing form. Does API allow for split reinforcing pads?

Thanks for your help.

 

[JStephen]

See API-650-5.7.5.1, which requires a tell-tale hole in each section if they are not made in one piece. I'm not sure if it's addressed elsewhere. I assume the split would be placed horizontally.

 

[JohnGP]

Yes, para 5.7.2.10 of API-650 says the same thing. The fact that it requires the telltale holes to be placed on the horizontal centreline suggests that the split should be placed vertically.

 

[IFRs]

API 653 figures 9.3 and 9.4 show a horizontally split repads

 

[JohnGP]

Hmm, interesting. I can see that one is more likely to encounter the need for split reinforcing pads for repairs on tanks, and API 653 is quite clear on how to arrange the split. Perhaps API 650 shouldn't be so prescriptive that each tell tale hole "shall be located on the horizontal centerline....". (But I can't imagine a tank being considered non-compliant with API 650 just because the tell tale hole on a one-piece reinforcing pad wasn't exactly on the pad centerline.)

 

[IFRs]

I would never split a re-pad along the vertical centerline - that is the plane of reinforcement! Split re-pads are not shown anywhere in API 650 and a new tank with split re-pads would technically not be in compliance with API 650. I find it hard to believe that for a NEW tank (API 650) you would not have the ability to bring in a one piece re-pad, therefore the telltale hole belongs on the horizontal centerline. I see lots of REPAIRED tanks (API 653) where a split re-pad is needed for a variety of reasons and there should be two telltale holes because the re-pads are separated by a weld which is always horizontal.

 

[JohnGP]

Beg to differ - API 650 does allow split repads, as referenced in the above clauses. It just doesn't detail their orientation. OP has come up with a situation where a split pad is needed - it's not specifically stated that it's for a new tank, but that's just a side issue, API 650 allows it, and API 653 provides some detail on its implementation.
[small](If I ever need a split repad I'll make sure that the split is on the horizontal centerline).[/small]
Cheers,
John

 

[IFRs]

John - You are quite correct. If I could retract my posting I would. I'm going to send a technical inquiry to the committee to resolve the issue.

 

[JohnGP]

Ok - no problem. (If one was allowed to retract postings then many of mine would have disappeared by now).

 

[wescburns]

Thank you for your posts gentlemen.