Case Histories

Pipeline Restoration at a Generating Station Using Chemical Grout

A gravity-flow water inlet line had developed many ruptures and cracks, leading to appreciable groundwater inflow. Contaminants brought in by the groundwater increased the cost of treating the water for station use. The problem was solved by injecting chemical grout to the exterior side of the pipe.

Effective Rehabilitation Planning for a Natural Gas Transmission Line—Part 1

This article describes the pipeline rehabilitation program developed by the natural gas transmission company in Colombia, South America. Part 1 presents the work accomplished to develop the Effective Rehabilitation Plan (ERP). Part 2 discusses the ERP in detail, including results and accomplishments.

MMO-Coated Titanium Anodes for Cathodic Protection—Part 2

Mixed metal oxide (MMO) anodes find extensive use in impressed current cathodic protection installations. Part 1 of this article covered the electrochemistry, manufacture, and operation of these anodes. Part 2 presents three case histories showing application of MMO anodes.

Real-Time Monitoring Affects Cathodic Protection

The need for real-time data is affecting the ability to provide cathodic protection (CP) to pipelines. The connection of electronic equipment required for remote pressure monitoring, metering information, valve operators, and other functions creates a direct short from the CP on the pipeline to the electric power company alternating current grounding system. In essence, the CP system now must protect not only the pipeline, but also a sizeable bare copper grounding grid. This problem creates pipe-to-soil potentials that may not meet the desired criterion. This article covers the use of decoupling devices to remedy this problem.

Copper Pipe Failure by Microbiologically Influenced Corrosion

After a detailed investigation on the failure of copper water service pipes in a water distribution system, microbiologically influenced corrosion (MIC) was found to be the cause. Increased system disinfection appears to have remedied the problem. MIC is often overlooked in corrosion investigations of drinking water systems. This case history is a good example of telltale signs of MIC and the water environments in which this can occur.

Corrosion Control Technologies for Wastewater Treatment Plants

Wastewater treatment plant components generally experience both atmospheric and immersion corrosion. Hydrogen sulfide (H2S), which is usually present, has wide-ranging effects in wastewater systems, most notably causing corrosion and odor problems. The corrosion problems can be mitigated by a combination of strategies including judicious selection and implementation of emerging corrosion-resistant coatings.

Cathodic Protection of Pipe Encapsulated in Polyethylene Film

Case histories are presented where polyethylene encasement and cathodic protection have been used together to effectively control external corrosion of ductile iron pipelines in corrosive soils. The four case histories evaluated include impressed current and galvanic anode protection.

Prevention of Micro-Flow Marks in Cathodic Electrodeposited Primer Coating in Automotive Industries

There was a defect of severe micro-flow mark lines in cathodic electrodeposited (CED) primer coating on car components. This problem was highlighted after final painting. This article describes the tests performed to determine the root cause of the defect. Tests included a surface profile of the CED coating and the determination of the microstructure and nickel content of the phosphate coating beneath the CED coating. The investigation identified the optimum concentration of nickel in the coating to refine phosphate grain size and create a unity crystal aspect ratio. It also found that the triple point junction of phosphate crystals determines the porosity to provide a uniform CED coating surface finish.

Centrifugally Cast Fiberglass-Reinforced Polymer Mortar Pipe for a Large-Diameter Interceptor Sewer

This article discusses one city’s approach to preserving the integrity of its infrastructure through the use of corrosion-resistant piping systems. Technological developments in centrifugally cast fiberglass pipes have provided installation advantages and lifelong benefits to municipalities.

Recent Fiberglass-Reinforced Plastic Applications: Radome and Hybrid Bridge System

This article describes two case histories: construction and installation of a fiberglass-reinforced plastic (FRP) radome and the design, construction, and utilization of composite FRP/concrete bridge beams. The shape, structural requirements, and radar transmission requirements of the radome are discussed, as are the design, fabrication, and testing of the composite beams.

Role of Nonmetallic Composites in Gas Plants

Several factors cause deterioration of critical process equipment in process plants. The options widely utilized for restoration include conventional repair or replacement. Nonmetallic composite materials can be utilized as an option to restore equipment integrity. This article discusses the material degradation aspects in critical streams such as the cooling water system and hydrocarbon pipelines at a Saudi Arabian gas plant. Nonmetallic composite coating materials play a vital role in corrosion protection and life extension of core components.

Advanced Coatings for Water Treatment Plant Components

Components of water treatment plants (WTPs) are susceptible to corrosion from constant immersion in water and proximity to chlorine. A case history of corrosion problems and their treatment at an Army WTP is presented. Solutions included using high micro-silica restoration mortar and advanced coal tar epoxy coatings.

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.