WHAT ARE THE APPLICATIONS OF CORROSION INHIBITORS?
Corrosion inhibitors are used in any application in which metals are in contact with water, or applications in which water may come into contact with metals. Most of these applications are encountered by industrial cleaning, metalworking fluids manufacturers and preventive maintenance professionals.
The term corrosion inhibitor is often used interchangeably to describe a number of very different products and, therefore, it is important to define to which type we are referring. For the purposes of this article, the term corrosion inhibitor will only refer to corrosion inhibitors that are used in the liquid phase (i.e. not those incorporated into coatings, since this is a very different industry).
The range of applications in which metals are in long term contact with liquids is vast and ranges from in-can applications for liquids stored in tins or aerosol cans, through water blasting/ pressure cleaning applications, all the way through to industrial lubricants and heat transfer fluids. Parts washing and impregnation, hard surface cleaning, and industrial cleaning, and anywhere where water is left to dry on a metal surface can also cause either surface discolouration, or flash rusting. Corrosion inhibitors are added to the cleaning products and the rinse water to inhibit flash rusting or discolouration in cleaning, parts washing, and impregnation applications.
HOW DO I SELECT A CORROSION INHIBITOR?
How well any given corrosion inhibitor performs is determined by the conditions under which it is operating. In order to select the most appropriate corrosion inhibitor and the optimal dosage for any given fluid, you first need to know the following information about the operating conditions:
• Is the fluid water-, oil-, or solvent-based?
• What is the pH of the fluid?
• Are there any dissolved corrosive salts?
• Which metals are affected by this fluid?
• For how long is the fluid intended to be in contact with the metal?
• Is flash rusting likely to be an issue while the metal is drying?
The answers to these questions will clarify the choice of corrosion inhibitor. For example, if the issue is flash rusting as water from blast cleaning dries on the metal surface, then the ideal corrosion inhibitor is Brad-Chem 563.
Clearly, corrosion inhibitors that are soluble in hydrocarbon solvents or oil are likely to have very limited solubility in water based fluids, a corrosion inhibitor designed for alkaline systems is unlikely to be compatible with or effective in acid systems, and so on.
WHY DO I NEED A CORROSION INHIBITOR?
Worldwide, the annual costs resulting from corrosion has been reported at US $2.2 trillion, which is over 3% of the world’s GDP. Corrosion inhibitors can reduce the damage caused to equipment as a result of corrosion, therefore reducing equipment replacement and maintenance costs.