Case Histories

Enhancing Asset Value Through Corrosion Management

The relative value of an aging asset depends on many parameters, among which are production rate/ continuity and integrity management (IM) costs. Reducing unplanned shutdowns and IM costs can maintain or even improve the relative asset value. This article describes—using data collected over a five-year period—how having asset corrosion management and risk-based inspection systems in place may achieve the above.

Interference Problems and Nonuniform Potentials in Cathodic Protection of a Complex Installation

After being in operation for some time, cathodic protection (CP) systems at compressor stations, refineries, and other industrial plants can experience problems. For example, the CP potential distribution can change for various reasons, because of isolating flange failures, alterations in pipeline systems, grounding systems, or reinforced concrete foundations. Some areas become underprotected and others overprotected. The extent of CP current required may exceed the capacity of rectifiers, and may also increase interference on foreign pipelines. This article describes the results of corrective measures for these problems.

Premature Coating Disbonding on Ships and Offshore Structures

Epoxy/urethane coating systems are widely used for ships and offshore structures because of their excellent resistance to ultraviolet radiation and protection against corrosion. Recently, some of these coating systems used in Korea experienced premature failure. This work investigated the root cause of the failures using pH tests and Fourier transform infrared spectroscopy.

Stress Corrosion Cracking of Various Alloys—Part 1

Stress corrosion cracking (SCC) can lead to rapid and catastrophic failure in many different metals and alloys. Failures often occur with little or no prior warning. A systematic approach is needed to evaluate any failure and identify its cause. The case histories in this article illustrate features that are commonly evident in various materials that experience SCC.

Stress Corrosion Cracking of Various Alloys—Part 2

Stress corrosion cracking (SCC) can lead to rapid and catastrophic failure. Failures often occur with little or no prior warning. A systematic approach is needed to evaluate any failure and identify its cause. This article continues the case histories begun in Part 1 and illustrate common features evident in SCC.

Effective Rehabilitation Planning for a Natural Gas Transmission Line—Part 2

This article outlines the results of a long-term pipeline integrity plan that was used to rehabilitate large segments of a natural gas pipeline over the past eight years. Part 1 of this article discussed the details to be followed in an effective rehabilitation plan to accomplish the goal of a well-maintained pipeline system.

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.

Caustic Treatment of Electric Utility Drum Boilers

Until recently, caustic water treatment was not used in high-pressure electric utility drum boilers in the United States because of concern over caustic gouging. Meanwhile, it was being used successfully in other countries. Many U.S. electric utilities have now converted their drum boilers to caustic treatment. This article describes the basics of caustic treatment and presents two case histories of successful use in the United States.

Long-Term Performance of a Fluoropolymer- Lined Process Vessel

An ethylene chlorotrifluoro-ethylene (ECTFE) lining of a process vessel handling alkaline-based fluids and active chlorine was examined after more than 23 years of service. The examination and tests showed that the ECTFE material was undamaged. Test procedures, data evaluation, and conclusions are presented.

Developing Welding Procedures for Sour Service

Controlling the hardness of the weld heat-affected zone (HAZ) in sour service is essential to help prevent sulfide stress cracking. It is important to evaluate HAZ properties when developing welding procedures. The behavior of specific alloys during welding presents roadblocks to HAZ hardness control. Two cases are presented to show that weld thermal simulation is an efficient tool for developing welding procedures for sour service.

Investigating Polyethylene-Encased Ductile Iron Pipelines

This article presents several case histories where ductile iron (DI) pipeline sections have been investigated to ascertain the corrosion control benefits of polyethylene (PE) encasement. The procedures and results of the investigations are evaluated and discussed. These investigations demonstrate the overall effectiveness of PE encasement as a corrosion control system for DI pipe.

Measurement of a Corrosion Inhibitor Through Online Monitoring

Typical repair of reinforced concrete structures showing corrosion damage involves removal of carbonated or chloride-contaminated concrete and subsequent retrofilling with new concrete. Corrosion inhibitors that can be applied by spraying onto the concrete surface are an alternative. These products are relatively new and only limited long-term monitoring results are available. The combination of an inhibitor with monitoring of the corrosion behavior provides evidence of protection. This article describes long-term monitoring results of protected highway gallery columns in the Swiss Alps.

Amine Blush in Epoxy Coatings

Carbonated amine material, often called amine blush, is the reaction product of the amine functional curatives in epoxy paint with carbon dioxide (CO2) and water vapor. This article explains the formation of amine blush and discusses factors controlled by the applicator and those controlled by the paint manufacturer.

Restoration of a Brick Chimney with a Dual Lining System and Polymer Concrete

A brick flue at a generating station was in need of rehabilitation because of the spalling and cracking of the brick. This caused a leakage of acid gases into the annulus. A typical flash coat system was not desired because of its relatively short life. A system of corrosion-resistant materials, which has shown excellent performance and durability, was chosen to make the repairs. The system consists of a combination of organic and ceramic-based lining materials. A case history is presented, with descriptions of the operating environment and materials selection criteria.

Designing Cathodic Protection for Power Plant Applications

Designing cathodic protection (CP) systems for buried piping in power plants and other similar industrial facilities offers several unique challenges. This article discusses these challenges and provides case histories to illustrate the impact they have on CP system design and operation.