Induction coating removal

[DBreyer]

Hi,

we have a large storage tank (70m) where we will have to renew the internal protective coating of the bottom and 1st shell course.
So far coating removal on our site was done by grit blasting which is quite costly and takes a long time.
There are some companies advertising coating removal via induction heating and then scraping it off as a cheaper and faster alternative.

Does anyone have experience with this?
Does the removal work at lap joints, too?
There is a worry that the hest will cause deformation in the steel plates, unfounded?
I assume we'll have to do a sweeping blast before reaplying the coating to get a really clean surface and appropriate roughness.

Any other pitfalls?

Thank you for sharing your experience!

 

[JStephen]

Assuming they're trying to sell the service, I'd inquire as to some past jobs they had used it on, and try to arrange an inspection of work-in-progress, or talk to the owners there and see how it worked out.
One issue is that typically, the entire removal/coating process would be contracted to one company. If you try to mandate that your regular contractors use a process they've never used before, you can easily have potential problems. As you note, much of the expense is in time, and if it just turns out to be excessively slow, then cost goes up correspondingly.
I would also be concerned with the deformation.
The roughness might require more than a sweep blast to achieve.
Another question is how hot the back side of the plate gets, or what happens with any pad under the bottom plate.
You could have some additional safety or nuisance concerns with the vapors generated.
It occurs to me the process might actually work better on thicker coatings than thin ones, which could be advantageous in some cases.

 

[MJCronin]

I agree with JStephen ...

If this contractor has a proven track record and has done many, many tanks successfully, then go for it

You don't want to be the first one on your block to try this

But, like JStephen, I am also trying to understand how the coating on the OUTSIDE of the tank is not destroyed ...similarly with the tank bottom pad

Also, what controls are in place to prevent overheating and warpage (especially on the tank bottom) ?

How about more information on the process ?

Please list some of the companies that offer this service

MJCronin
Sr. Process Engineer

 

[DBreyer]

Thanks for pointing out additional tobics to be aware of.

Here is a link with some videos and information on the technology:
[URL unfurl="true"]https://www.rprtech.com/coating-removal-on-storage-tanks/[/url]

 

[SJones]

It's all about the skin effect: Ambrell Induction Heating along with the procedure, and operator training.

RPR was the main hit when I Googled, and the experience listing looks reasonable, however, it's about the team that turns up on the day. I couldn't see any quality system certification details for them either - something to check on, especially with their "network". From an HSE point of view, it's got to be better than blasting. HP/UHP water jetting might have got you better productivity in removal than blasting too.

For recoat, you will need much more than "sweep blasting". Check the datasheets of the coating that you plan to use.



Steve Jones
Corrosion Management Consultant

http://www.linkedin.com/in/drstevejones

All answers are personal opinions only and are in no way connected with any employer.

 

[LittleInch]

Interesting.

Not sure what they have managed to patent, but it would appear to be a small spot heating bar about 12" long? which rapidly heats what I guess is the outer skin of the plate. Note the burning of the paint in the videos - looks like spot temps are quite high, so you will need to make sure you don't create a hazardous atmosphere in the tank. Full BA looks like a good move to me or full face respirator, not those poxy little face masks the guys have on.

Do you have a lot of tanks? Could you get them to do a trial?

How hot does the tank get after a while?
What is the spot temperature and how do they control it?
Anything over 2-300C could impact the steel

And then you still need to blast clean it of the next coat, but you need to do the calculations and look at time etc.

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

 

[HTURKAK]

Dear DBreyer (Materials),

Some years ago i got the draft of EN ISO 16961 ( Internal protective coating and lining of above ground steel storage tanks )..

Clause 7.7.1
The use of induction coil heating machines to destroy the bond of the existing laminate lining followed
by lifting and removing segments of the laminate during maintenance lining/re-lining work may be approved in
lieu of removal by abrasive blasting, subject to Client approval.


When you watch the video at link you have provided and others available at web , one can see that , sand blasting should be conducted after induction coil heating and the laminate is removed ..In this case, induction coil heating could be reasonable for lining ( rtr etc)rather than paint.. Another concern is the coating (if) under the bottom plates.

https://www.materialsperformance.co...ign/2022/02/coating-removal-by-heat-induction

When you decide upon the use of induction coil heating , please share your findings and experience with us and keep us involved..