Chemical Treatment

Corrosion Inhibitors

An inhibitor is a substance that slows down a chemical reaction (in the present context, a corrosion reaction). Corrosion inhibitors are commonly added in small amounts to acids, cooling waters, steam, and many other environments—either continuously or intermittently—to reduce the intensity of corrosion that might otherwise threaten the intended design life of a structure.

Microbiologically Influenced Corrosion in a Copper Tube Chiller

The increased use of recycled water has led to the need for an effective water treatment program to prevent microbiologically influenced corrosion (MIC). This article describes an investigation of copper tubes in a chiller that failed from MIC because of a poor water treatment program.

Tuberculation Corrosion in Industrial Effluents

Tuberculation in waste water has long been a concern. Causes are an adverse mixture of water chemistry, construction materials, microbiological attack, and flow rate. Low velocity permits particulates and corrosion products to form deposits. Accumulated deposition leads to partial or complete blockage of pipelines, trapping of pigs, under deposit corrosion, and tuberculation. Tuberculation reduces flow rate. This article discusses tuberculation and presents a case study.

Lead Contamination of Condensed Water

This article presents experimental data that show the solubility of lead in different waters. Specifically noted is the solubility of lead in condensed, or “pure,” water. It provides introductory information to those just entering the field of water corrosion and contamination as well as basic information to others not familiar with water corrosion and contamination.

Review of Applicable Indices for Evaluation of Water Quality

This article compares three water quality indices for the evaluation of water to be used in industrial processes in Iran. They include the Puckorious Saturation Index, Langelier Saturation Index, and Ryznar Stability Index. The most applicable index for use in that country is suggested.

Failure Analysis of a 30-in Subsea Oil Pipeline

This article presents the failure investigation of internal pitting corrosion on a 30-in (0.762-m) diameter subsea oil pipeline in western offshore India. Detailed laboratory and analytical studies were made on the failed sample to establish the cause and mechanism of failure. This article describes the analysis methodology, the probable corrosion and failure mechanism, and recommended preventive measures.

Special Considerations When Using Inhibitors

An inhibitor is a substance that slows down a chemical reaction (in the present context, a corrosion reaction). Corrosion inhibitors are commonly added in small amounts, either continuously or intermittently, to control serious corrosion in aggressive environments such as acids, cooling waters, and steam. While they can be highly effective, many inhibitors are also toxic, particularly in the concentrations suitable for shipping and storage. It is important to employ precautions to ensure personnel safety, environmental protection, and uninterrupted operation of equipment.

Corrosion by Water

The concentrations of various substances present in water in dissolved, colloidal, or suspended form are typically low but can vary considerably. The importance of these concentrations depends on the particular substance as well as the alloy, configuration, and function of the metallic structure with which the water comes into contact.