Aboveground storage tanks hold various types of products; some are more corrosive than others. The key to corrosion protection is to adequately review your tank and its contents to ensure a safe operational life. This can be done using NACE consultants or properly qualified personnel on staff at your company.
Corrosion is the deterioration of a material that results from chemical or electrochemical reactions with its environment. Tank corrosion references such as API 650, 651 and 653 need to be taken into consideration along with Regulation 40 CFR part 112.
Corrosion is caused by four components:
- An anode — anodic reactions occur (metal dissolution),
- A cathode — cathodic reactions occur,
- An electrolyte — in contact with an anode and cathode, or
- A metallic path — electrical connection between the anode and the cathode (tank surface).
There are several options that can be taken to avoid tank corrosion:
- A preventative option using corrosion resistant materials.
- Remove any one component of the corrosion cell.
- Create a barrier between the corrosive environment and the metal surface by using coatings or linings, which are the primary defense.
- Sacrificial anodes can be used to support the coatings such as aluminum, for example.
Corrosion risk mitigation can be achieved by having corrosion prevention measures in place along with maintenance that supports the corrosion prevention measures. Corrosion monitoring results need to be used as a tool to mitigate corrosion. Proper and timely inspections need to be a part of the routine. Proper training and record keeping for dedicated resources are important to corrosion prevention success.
Dharma Abayarathna, Ph.D., provided expert consultation for this article.
For more information, email info@mesaetp.com, visit www.Mesaetp.com/talk-to-a-tank-expert or call (866) 368-7532. •
