In recent years, glass lined bolted steel tanks have become more frequent despite the higher initial cost. The arguments for a glass lined tank are simple: glass coating is non-porous and very rigid. Therefore, the theory is that liquids cannot reach the steel and cause corrosion, which could destroy the tank.
Unfortunately, there are a few details which impact performance of glass lined bolted steel tanks in real life. First, great care must be taken when shipping, unloading and installing steel staves to not crack the glass overlay as cracks will allow water and liquids to penetrate the enamel coating. A particular area of susceptibility is the edge of steel staves as the hard and brittle glass coating is vulnerable to impact. Even minor damage to the edge can result in a catastrophic failure of the enamel coating system. Once the glass lining has been compromised, the steel will begin to corrode under the glass coating, resulting in the coating delaminating. As the glass lining of the tank is fused to the steel at very high temperatures at the factory, this process cannot be replicated in the field. The only way to attempt to correct damage is by covering the area with mastic putty. Not only is this unattractive, but the putty mastic can peel off over time, re-exposing the damage underneath.
In comparison, factory powder coated bolted steel tanks manufactured by Superior Tank have been laboratory tested to be considerably more durable. The powder coating is flexible enough to endure normal impact without cracking. If the impact is severe enough and the coating is compromised, our propriety SiZr seal will prevent the spread of corrosion and coating undercutting. Repairs to damaged powder coating are very simple and can be performed in the field with outstanding results.
A second consideration with glass lined bolted steel tanks is the use of mastic in place of proper gaskets. The mastic has several drawbacks such as it can dry out before the steel staves can be fastened together, leading to cracks and improper adhesion. To attempt to prevent the mastic from drying out, the panels can be installed and tightened one at a time, but this results in uneven tightening of bolts. Also, manufacturers of glass lined bolted steel tanks will recommend the mastic be scraped out and replaced on a regular basis. A final concern when utilizing mastic is it’s incompatibility with crude oil or other hydrocarbons.
All Superior Tank bolted steel tanks are manufactured with pre-punched synthetic rubber gaskets. Our heavy duty gaskets allow entire sections of our tanks to be installed and tightened evenly all at once, producing a uniform and issue free assembly. In addition, our tank gaskets remain pliable and in firm contact with the steel surface therefore preventing leaks. For storage of different liquids, Superior Tank utilizes several types of heavy duty gasket materials such as Buna-N for crude oil and hydrocarbons and EPDM for potable and wastewater.
When all of the facts on glass lined tanks are accounted for, the truth is clear; factory powder coating provides equal or superior results for less money.