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316L coating problem on 100 ft high column

I have been asked to remove a coating from a 316L column 100ft high and 5ft diam. and repalce same with an acid resistant polyurethane coating. The proposed purpose of the coating is to inhibit the corrosion of the column which has been eaten away by the contents which is a resin prill in 20% sulfuric acid. The reacted product is called Reddox and the temp. is 35 °C. Surely this corrosion is abnormal? I plan to pressure wash with clean water and abrasive grit blast to remove all the old coating before applying a holding primer. Any suggestions please or advice?

Gordon Cornish
Manager - Klerksdorp, North West Province, South Africa
2003

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2003

Hi Gordon,

1. Re your coating, Pu is absolutely excellent in abrasion has superior flexibility and, I would have thought, in a weak sulfuric should be OK ,,, but in our corrosion applications we never used it. Also at the top of this, I assume, internal tower/column, would it be UV resistant?

2. One U.S. Company makes/made acid resistant liners for chimneys. Custodis Chimney. One of their larger ones was a l2 foot x 200 foot high chimney in the Dominican Republic. These large diameter sleeves were made in (I forget!) 6 foot long sections and had a socket to 'lock into'. They were made by Alcore Fabricating in Richmond Hill, Ontario.

What I'm suggesting is that perhaps you might consider a thermosetting resin ... we used to use Hetron l97 polyester because of its high heat properties ... and line the tower with a suitable thermoset BUT always with at least one mat because a pure resin coating can crack !

What one must also consider is PERMEATION ! Whatever you do, please double check this point ! I do know of instances were m.s.reinforcers failed (Steel Co. of Canada)due to acid permeation through the frp ... had they used PVC as the internal lining, that would not have happened.

A competent fibreglass 'shop' would be able to give you some help.

Freeman Newton [deceased]
(It is our sad duty to advise that Freeman passed away
April 21, 2012. R.I.P. old friend).