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Paratene™ ACI
A New Approach To Acid Corrosion Inhibitors

Introduction
Strong acids and chelating agents are used in a variety of applications, where corrosion inhibition is required, including oil well acidizing, chemical cleaning and metal pickling. In most cases the solution to be used is selected both for the ability of the cleaning solution to remove the deposit but also for the compatibility of the cleaning solutions with the materials to be cleaned.

Acids (and chelants) will often corrode the base metal. To prevent the damage we apply corrosion inhibitors. A number of commercial corrosion inhibitors are available. The choice of inhibitor depends on the conditions – that is the type and concentration of the acid, the material to be cleaned, the expected contact time and the anticipated maximum temperature. Two separate groups of chemicals are typically used for corrosion inhibitors. The first, for hydrochloric, often contain a combination of unsaturated oxygen compounds, such as acetylenic alcohols, unsaturated ketones, in combination with nitrogen based materials such as quaternary or secondary amines.

The second type or class of inhibitor is used to protect against corrosion in solutions of organic acids, chelants or sulphuric acid (but not nitric acid). These products use a reduced Sulphur compound such as thiourea or ammonium thiocyanate in combination with a nitrogen contain quaternary or secondary amine.

The new product Paratene™ ACI represents a major change in both the approach and the versatility of acid corrosion inhibitors. This paper will describe a new class of corrosion inhibitors that inhibits all acidic solutions including nitric acid under a wide range of conditions.

Corrosion Protection and Performance
Paratene™ ACI has been tested in a variety of acids and conditions. Based on these tests ACI can be used in dilute acids (5% or below) at temperatures up to 80°C and in stronger acids (10%) up to 60°C.