Tank shell plate replacement 1

[Guibar]

Hello everyone.


I will have to replace 3 entire shell plates of our naphta tank. They are side by side in the third level out of six.
Where can I find information how I have to procede, the correct sequence of each step.

Appreciate your comments/thoughts on the above.

 

[fegenbush]

I would advise to seek the advice of an experienced tank repair engineer. There are many factors to consider and a slight mistake could result in loss of life or property.

 

[Guibar]

I appreciate your concern, but I wanted to Know if there is any API guide or something else where I could find some guidelines or good practices to do this job.

regards

 

[JStephen]

Typically, repairs would be per API-653, which references API-650. Note that the standards don't cover things like rigging and fit-up, so the actual procedures used are not specified in detail.

 

[Duwe6]

I too suggest you get the services of a 'Tank Guy'. Replacing that much shell will distort your tank unless the weld fitups, progression, and sequencing are 'just right'. Many mechanical contractors have turned nice, pretty, round tanks into hexagons, octagons, ugly messes due to inexperience with the combination of large diameter and very thin shell.

But if you follow the [very conservative] rules of API-653, you will have a safe tank.

 

[LittleInch]

How big a percent of the circumference is the three plates?. What's the diameter of the tank?

A ridiculous as it might sound you might want to consider complete removal of the top three rings and rebuild from there. At least you still have the base, bottom two rings and nozzles. API 650 tasks are highly stressed and very thin compared to diameter and not designed to allow this sort of repair without serious reinforcement during the work. An alternative might be replacing your three plates with many more smaller ones one at a time...

You need the tank guy the others are talking about.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[Guibar]

The tank has 323 ft of diameter. The tree plates represents 12% of it.

 

[Duwe6]

With a tank of that size, you don't procede. You hire the best Tank Design & Erection firm you can find, and allow them to handle it. I've done a bunch of tank modifications and repairs, and on this one I would call Chicago Bridge & Iron. This repair is akin to working on a 50-story building or 1000-ft / 300m long ship. If you havn't done several, successfully, you don't touch it; you hire an expert, experienced firm and listen to them.

 

[MJCronin]

Dumb question:

Why do you want to replace only a few sheets up high on this tank ?

My experience has been, usually only the bottom and bottom course of many tanks corrode away.

Replacement is typically done to the bottom of the tank

( Note: Concentrated sulfuric acid is an exception to this rule)

What is causing the problem with your naptha tank ??

MJCronin
Sr. Process Engineer
Venture Engineering & Construction

http://www.VentureEngr.com

 

[Guibar]

Hello all. thanks for your advising.

We still don't know exactly what happen to the tank. We are checking out some companies to get the job done.

 

[fegenbush]

Duwe6,

While I agree that CB&I is a competent tank contractor, they are not the only one. There are several other tank contractors that may be able to offer a competitive advantage. Those of us on here who work for one of the other competent contractors with an excellent safety record appreciate being included in such listings.

Apart from that, I think your point is spot on.

 

[Duwe6]

fegenbush, no slight was intended. The only international tank company that I personally know well enough, and is good enough to recommend without any reservations is CB&I. This just reflects on the paucity of my personal knowlege, and nothing else. If I knew more, I would list more. But I do all my work in the USA, so I am pretty limited.

 

[Guibar]

The only problem is that I am i Brazil

 

[Duwe6]

fegenbush, any alternative contractors that will work in Brazil? CB&I is one option, GUIBAR. It is possible that something this 'ticklish' may be more than a local firm can handle. Yours will be a VERY tough repair to make.

 

[fegenbush]

I would be reluctant to provide a contractor since I would either be self promoting or recommending a competitor.

However, I don't think that GUIBAR could go wrong asking Phil Myers (

http://www.pemyconsulting.com)to

consult on this project.

 

[Duwe6]

IMHO, it is not "self-promoting" if your company is genuinely competent, and one of the best choices. The facts are the facts, good engineering is good engineering.