Storage Tank Bottom Replacement 5

[Inchtain]

Hello,

Does anyone have a procedure or advise on replacing all corroded bottom plates in a tank? and do you think it is necessary to cut one shell plate to take the new plates inside and replace all the bottom media underneath the plates, as the tank was leaking under?

Thanks for the support

 

[IFRs]

WIthout reading the attachment, my opinions:

Sand should be the top layer. Stone will encourage corrosion.

Soil resistivity is only one criteria when evaluating the need for CP.

I've made floating suctions from carbon steel, coated carbon steel, stainless steel and aluminum. It all depends on the service and cleanliness requirements. Problems with the floating suction are often traced back to the design and the parameters the owner gave the designer, particularly the product density. Although poor quality components can be a problem also. Need to know what the problems were to help any more.

Door sheet height is goverend by the equipment coming in inside. 2100mm could certianly work. Door sheets can extend to the round seam, they can extend past or stop short of the round seam, they can extend to or stop short of the corner weld. It's all up to you and your contractor. Don't forget to brace hte opening to avoid shell distortion that may start at the upper corners of the opening and extend up and to the side at a 45 degre angle.

 

[Inchtain]

Dear Sirs,
Can we have the option of keeping the annular plates based on the MFL report (attached) with reference to API, by doing some patching or extending the new bottom plates to cover the defected areas?

Additionally, can I have your comments on the sacrificial anodes installed, in terms of the shape and the quantity (16 anodes for 37.2 meters diameter)? Photo attached.
Do you think that the presence of Sulphide Reducing Bacteria (SRB) could cover the anodes and prevent their function?

Thanks and best regards,

 

[Inchtain]

Here the MFL findings of the annular plates

 

[LittleInch]

Inchtaain,

This post has moved into the realms of free engineering here. I note your previous response

"Actually, I've followed a tank construction project before.
However, maintenance is different."

It is indeed different and following a single construction project, whilst very useful, is no substitute for following many different projects. What exactly is your role and position in this piece of work?? It does seem to me like you are out of your experience range here so I think you need some help locally.

I can only suggest that to answer your questions you employ an experienced tank repair consultant / firm who can review all of the information you have ( and not drip feeding information) and present you with different costed options which they are then responsible for taking into account your location, any access issues etc.

The anodes will only be effective when they are immersed in the water layer which may exist at the base of the tank.

The consultant will be able to review the operational life of the tank, type of coating, inspections undertaken, type of foundation etc much better than we can.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[Inchtain]

Dear Sir,

Thanks for your involvement.

I am a Plant Inspector and I posted some queries here to broaden my horizons and share ideas with experienced engineers; and that the purpose of this site as I guess.

Sometimes, I know exactly what is needed but I like to exchange the confirmation by others who have had worked in similar projects.

Every point said previously was interesting and I am positively sure that many will benefit from this thread.

So, let's continue the good job

Thanks anyway.

 

[LittleInch]

Well yes it is, but we don't have the full set of design draiwngs, operational life, inspection reports, photos, type of internal coating, budget for repair etc

E.g. I have no idea why those anodes are so far off the floor when you're storing Crude Oil, but was the tank originally designed for something else?

So take your paragraph above on the floating suction. There is no detail, no drawings, no pictures, no operational life data but you ask 7 questions without giving us any idea about your opinions or thoughts. People here, especially IFRS, are good and have lots of experience, but we can only see what you show us. It's far better to start a post with some data and an explanation of what your are doing, your roles and some specific questions.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.