Rerate of a Lap Welded Tank for Nitrogen Pad (oil service)

[craengr]

I have a lap welded shell tank (< 15 psig)in oil service that I plan to add a nitrogen pad to. I have no drawings nor any code information about this tank. I have all the data (thickness, material..etc) to rerate this tank for the nitrogen service. It doesn't look like it falls into API 650 or 553. Any ideas on methods to come up with a pressure rating or codes I can use to rerate this tank?

Thanks

 

[MJCronin]

craengr

To the best of my recollection, lap welds on a tank typically means that the tank is either designed to AWWA D100 or to no code at all.

Are the lap joint welds on the roof or on the shell and roof ?

Your particular problem, to me, is the reason why that there should be greater state and federal oversight of tanks and pressure vessels.

We can register, tax and keep track of cats, dogs, hairdressers, engineers etc...... but most states do not keep track of these old "zombie" tanks that are sold over the years from company to company.

The building inspector and the tax authority in the smallest of towns can tell you how many bedrooms, bathrooms and the dates of construction was for even the smallest of houses.

But they can't tell you anything about the 100,000 gallon tank at the end of the street....!!!!!!

As a minimum, we should have a system like Germany does, Register, inspect and keep detailed design records (like you need) FOR ALL OF THE TANKS IN THE STATE..!!!

WHY IS THIS SO DIFFICULT ???

Whew......I feel better..

-MJC

 

[chicopee]

Craengr, this is the most absurd thing I ever heard. Get the proper tank for such application. Talk to your nitrogen supplier.

 

[roca]

what is a nitrogen pad?

 

[786392]

Probably Blanketting with Nitrogen gas?
Just fishing I am!

Best Regards
Qalander(Chem)

 

[roca]

yes thats what i was expecting

 

[IFRs]

Blanketing is ordinarily at just above atmospheric pressure and so may be suitable for this tank. If he is just inerting the vapor space, and keeps the pressure below the weight of the roof plates he may be OK. How large and what is the liquid stored and what pressure is expected?

 

[786392]

4.5~8.5 mm WC(Water Column) or as per estimated withholding strength!
I believe.

Best Regards
Qalander(Chem)