The diffusion plates within the process tank had corroded to a point of replacement being required. To extend the service life of the new plates the client had elected to install these in stainless steel. This raised the concern of galvanic corrosion of the existing mild steel tank shell.
To protect the mild steel tank structure from galvanic corrosion a suitable tank lining was required.
The operating conditions of the tank could be up to 100 degrees centigrade, with the injection of carbon dioxide, creating an acidic environment.
For these conditions we proposed the application of Chemco Internationals RB300 glass flake reinforced vinyl ester as the most suitable tank lining due to its combination of good chemical resistance and temperature resistance.
Initially all surfaces were prepared by method of abrasive blasting to remove existing scale, corrosion and to raise a minimum surface profile of 75 micrometers.
As part of our standard quality assurance a soluble salt test was conducted following abrasive blasting. Unexpectedly a slightly elevated result was detected and the client informed and advised of the potential risks. Given the very tight program constraints it was not possible to wash and re-blast so the decision was made to proceed.
All angles and edges received stripe coats by brush to ensure full film build. This is particularly imperative in demanding environments such as tank linings which are subjected to high operating temperatures and chemical attack.
Applying the Chemco RB364
Chemco RB364 was applied in three coats of contrasting colour to achieve a total tank lining thickness in excess of 1000 micrometers.
The tank lining was checked for pin holing using a DC holiday spark tester. Where found pin holes were marked prior to touching in using the same material applied by brush.