Application of Epoxy Phenolic Coating

[ak1965]

We have a stripper tank coated with Epoxy Resin ( 125 micorn DFT)on inner surface of it.

The tank handles Oxidized Neutralized Caustic Water, however the pH fluctuates dangerously and ranges between 4 to 11.The Service temp. is 50 deg. C

We are encountering frequent failire of tank wall and wall thinning has also taken place. Design Wall Thk: 5 mm

We have decided to replace the Epoxy Resin coating (125 mic) with a Epoxy Phenolic coating (150 mic DFT).

What is the difference between thse 2 coatings? Is Epoxy Phenolic Coating better than Epoxy Resin Coating for the given application?

Thanks.......

 

[unclesyd]

We found that the epoxy-phenolic coatings are better than the several epoxies we immersion tested in the laboratory in a neutralization process very similar to yours. We have two large open roof tanks that were coated with as epoxy and it failed in about a year. When we went to clean the tank for the new coatings we found areas where there was almost pristine material, we had no clue as to why the bonded and non-bonded material. When the tanks were blasted and ready to apply the epoxy-phenolic coating we caught one of applicators stirring the coating mix with a broom handle. When confronted about using the stick instead of the mixing equipment supplied. He answered that was that's the way it was done the last time.

I believe that the epoxy-phenolic material will do a better job if properly applied, as per the manufacturer's instruction.

Check you lining material specifications as at one time there was temperature limit on some epoxy-phenolic materials. If I recall this was around 200F.

 

[ak1965]

Dear Unclesyd,

Thanks.....for info.... we also conducted immersion testing for 10 days ...the sample coated with Epoxy Phenolic coating repsonded very well @50 deg. c under stirring.

I think 10 days immersion testing should be sufficient ??

what can be the approx cost to coat a 31 Sq. Meter tank with epoxy Phenolic Coating ?

 

[unclesyd]

We try to run coating or paint tests a little longer with approximately 30 days at the very minimum for linings and 1 year minimum for paints exposed to the elements.
If you have the time I would run the test a little longer and vary the PH. I would also use a scratched sample.

I've been out the system so long I wouldn't want to hazard a guess to the current cost. The last number I remember from the early 90's was $87/gal. It would be best to get with your supplier and get the product data sheet and start from there. The data sheet will give you the approximate coverage and millage so you can go from there. Make sure you follow instructions on how to get millage you require.

Make sure you follow the job from the beginning to end. Use both WFT and DFT gauge tester. Follow up with a "bird dog" to look for holidays. Try to use an airless system if possible. We also required the applicators to wear full body personal protection gear and a breathing air mask.

 

[gerhardl]

For difficult jobs we always use professional companies with experience and references for offshore. Offshore coating job are normally the most difficult and demanding, and requires proven and documented procedures and test and certifications for the actual coating done.

Any coating adhesion and quality is depending on surface preparation, appliction methode, quality of coating components and mixture, temperature and work/layer quality in general.