DEAR ALL . I am working on the mai

[thaierali]

DEAR ALL
. I am working on the maintenance of the ROOF of one of the of diesel fuel tank with capacity of 10,000 cubic meters. The roof replacement was taken at a thickness of 5 mm. The upper part of the shell was severely eroded with a design thickness of 6 mm. Measurements averaged 4 mm.
My question is whether it is permissible to replace the roof without replacing the the top shell Note that the thickness of the design surface is 5 mm. and What is the corrosion allowance of the upper part of the shell where it is not accurately defined in the API650 and it returns its appreciation to the investor

 

[WARose]

My question is whether it is permissible to replace the roof without replacing the the top shell

This may be the wrong forum for this question. But I would think the answer would depend on a analysis (on your part) of the shell to see if a corroded shell can take the loads you have. I've used a pressure vessel handbook for this in the past (for certain tank diameters).

 

[Ron]

What type of roofing is contemplated and how will it be installed? The service load of installation and the safety of workers must be considered. Further, any perforation of the roof shell will affect and compromise essentially any roof covering system. This will lead to contamination of the product through emulsification/solutioning of the roofing materials, not to mention the direct leaks of water into the product.

 

[thaierali]

thanks all
i will try to make my question clearer > the issue is a conic roof tank with capacity 10000m3 . the roof is severely damaged by corroding > we decide to replace the roof plates with new ones with same thickness of the designed roof thickness is 5 mm > the problem is that the top part of the shell is croded down to 4 mm while the design thickness is 6 mm >
mu question is >>>if i go on with repalcing the roof plates only we will have a tank with roof plate thicker than the top shell >>>is that acceptable !!! and if it is not acceptable can i take this issue as a resonable reason to Take a decision to replace both roof and top sell plates

i hope i make my issue clear enough
thanks for your Patience

 

[WARose]

mu question is >>>if i go on with repalcing the roof plates only we will have a tank with roof plate thicker than the top shell>>>is that acceptable !!!

Still not sure I 100% understand the question (or if this is the right forum)......but pressure vessels gets "pads" (i.e. plates) added to them all the time for locally concentrated loads to thicken it.

 

[SnTMan]

https://www.eng-tips.com/threadminder.cfm?pid=1452

The problem with sloppy work is that the supply FAR EXCEEDS the demand