Soil-side corrosion of aboveground storage tanks is a chronic problem in the industry. It is a principal cause of storage tank failure and imposes a major environmental and operational challenge worldwide.
Different foundation construction methods and corrosion protection systems have been implemented over the last several decades, in attempts to mitigate and control soil-side corrosion. Such as the use of asphalt pad, bituminous sand, cathodic protection (CP) and coating.
However, total effectiveness of these techniques, as standalone or combined, have been questionable in providing the required protection, especially against pitting corrosion.
The inevitable presence of air gaps between the bottom plates and at the tank pad, due to hydrostatic stresses and filling and emptying cycle, and at weld overlaps shields the Cathodic Protection current in these areas.
Corrosion of the underside of the tank bottom plates leads to metal loss and ultimately perforations in the tank floor. The results of such failures are substantial on multiple fronts:
- Unscheduled interruptions
- Loss of products
- Costly repairs and safety concerns
CorroLogic® System for Aboveground Storage Tanks (AST)
In the last 20 years, the use of Corrologic® Vapor-phase Corrosion Inhibitor (VpCI®) has grown significantly. With more than 600 tanks currently protected by Corrologic® systems, confidence is growing in this important technology.
CorroLogic® Volatile Corrosion Inhibitors (VCI) are Amine Carboxylate based. They provide protection by a combination of volatilization from the VCI source, and adsorption onto surfaces where the rate of soil-side corrosion of the bottom plate is thereby inhibited
The volatile nature of the inhibitor allows it to mitigate corrosion in hard-to-reach areas and supplement the Cathodic Protection (CP) for increased overall corrosion protection.
VpCI’s are effective alone, or in combination with CP. It is important to recognize that VpCI® chemistry is well proven for over 40 years and been utilized by many major corporations around the world for a wide variety of applications. The system can be applied to New Tanks, Out-of-service Tanks, and In-service Tanks.
Tank owners and operators are adopting CorroLogic® AST Solution to protect tank bottoms and extend the service life of the tank. CorroLogic® AST Solution provide several advantages such as:
- Reduce the pitting corrosion and metal loss thickness rate
- Extend tank inspection interval and the service life of bottom plates
- Monitor and analyze the corrosivity of the environment under the tank to ensure the inhibitor is controlling the corrosion rate and keeping it low
- Compatible with Cathodic Protection