June 4 - June 8, 2012
How do you remove all traces of an uncured internal coating from a tank when abrasive blasting is not an option?
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Josh Inklovich of Total Coating Solutions on
June 8, 2012:
This is a tricky one. I have had to do this on numerous occasions when an "experienced" coating applicator neglected to add the part B's to the part A's in a 1:1 mix product. I can only advise what we have done: 1. Use scrapers to remove as much uncured coating as possible. Scoop and throw it in a bucket. 2. Solvent wipe the remaining material. Jeremi mentioned using MEK. My suggestion is to use the solvent recommended by the manufacturer. Different coatings more fully dissolve in different solvents. Use stiff bristle brushes and ample solvent to get the uncured coating out of the profile. Obviously, utilize air moving equipment and "sniffers" to detect levels of vapors. Your men should be wearing tyvek suits, spark-resistant foot covering, and spark-resistant (i.e., non-metallic) tools during this entire operation.
Additionally, forced air, full face respirators should be used. 3. Use lint-free, solvent-soaked rags to mop up the remaining material. Keep cleaning until the rags are clean after wiping. 4. After this is done, we DID reblast everything with Starblast each time this was encountered (3 times in 12 years). You now have another potential issue. If you can't blast, how are you going to prep the surface for relining?
David Grove of Shaw Nuclear Power Services on
June 13, 2012:
One key in removing uncured coatings is to keep in mind that if the material can be changed into a physical state where it is no longer "sticky" to the substrate, then it will be easier to remove. In many cases, high heat will make this happen, and there are a number to tools that will do this. Of course, a second surface preparation will still be required for reapplication.
Murjan Murjan of Sirte Oil Company on
June 12, 2012:
The first thing is solvent cleaning and abrading the old coating ,then use SP 3 power tool cleaning. After that, blow down and coat the surface.
Jeremi Day of Allphaz Inspection Services on
June 4, 2012:
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Unfortunately, a strong solvent such as MEK must be used. Two drawbacks come with this solution. One is that it poses as somewhat of a safety hazard to the crew. They should wear respiratory protection, double eye protection, and chemical gloves at a minimum. The other is that they must use plenty of rags and the rags should be white rags, which are more expensive. If color rags are used, the dye will transfer from the rags to the substrate, which will present yet another problem. The crew will have to use a large amount of rags and solvent. If not, as the rags and solvent get more and more dirty with the un-cured coating, it will transfer back onto the substrate. Also, brushes should be used to remove the un-cured coating from the crevices of the weld seams. In my experience, this is the best way to remove all traces of the coating without blasting. The only other solution I can think of is to wash with UHP. In some instances, depending on the coating, this may cause more problems.
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