Search Results for accelerating corrosion

Complete vehicle accelerated corrosion testing on the proving ground is a mandatory testing tool among vehicle manufacturers around the globe. This article focuses on creating some awareness of the difficulty in applying reliable corrosion tests for all corrosion-sensitive automotive systems at once. It describes the various factors for a complete vehicle testing, including wear from road grit, dirt, salt load, elevated temperatures, and mechanical effects such as chafing and fretting. The article discusses the four main test blocks, namely, driving sequence on various proving ground tracks, exposure of the vehicle in one or more ways to road deicing salts, static exposure to forced climatic conditions, and additional elements such as operating the mechanical systems of the vehicle, car washes, and so forth. It concludes with information on the major advantages and drawbacks of a full-service-life test.

This article briefly describes water and steam chemistry, which influence the effect of corrosion in boilers. The appropriate control measures to prevent corrosion in boilers are also presented. The article provides a discussion on the common causes of fluid-side corrosion such as flow-accelerated corrosion, oxygen pitting, chelant corrosion, caustic corrosion, acid corrosion, organic corrosion, phosphate corrosion, hydrogen damage, and corrosion-assisted cracking.

This article presents the primary considerations and mechanisms for corrosion and explains how they are involved in the selection of materials for process equipment in refineries and petrochemical plants. It discusses the material selection criteria for a number of ferrous and nonferrous alloys used in petroleum refining and petrochemical applications. The article reviews the mechanical properties, fabricability, and corrosion resistance of refinery steels. It describes low- and high-temperature corrosion, hydrogen embrittlement, and cracking such as stress-corrosion, sulfide stress, and stress-oriented hydrogen-induced cracking. The article considers hydrogen attack, corrosion fatigue, and liquid metal embrittlement and the methods of combating them. It explains the causes of velocity-accelerated corrosion and erosion-corrosion. The article summarizes some corrective measures that can be implemented to control corrosion. The applicable standards for materials used in corrosive service conditions in upstream and downstream petroleum service are presented in a tabular form.

The rate and form of corrosion that occur in a particular situation depend on many complex variables. This article discusses the rate of corrosion of lead in natural and domestic water depending on the degree of water hardness caused by calcium and magnesium salts. Lead exhibits consistent durability in all types of atmospheric exposure, including industrial, rural, and marine. The article tabulates the corrosion of lead in various natural outdoor atmospheres and the corrosion of lead alloys in various soils. It explains the factors that influence in initiating or accelerating corrosion: galvanic coupling, differential aeration, alkalinity, and stray currents. The resistance of lead and lead alloys to corrosion by a wide variety of chemicals is attributed to the polarization of local anodes caused by the formation of a relatively insoluble surface film of lead corrosion products. The article also provides information on the corrosion rate of lead in chemical environments.

Chemical-mechanical planarization (CMP) of metals is described as mechanically accelerated corrosion, erosion corrosion, or metallic corrosion enhanced by wear. This article reviews the history, process, chemistry, electrochemistry, and defect issues for CMP. It provides an overview of CMP through a schematic illustration of CMP process equipment. The applications of CMP to tungsten and copper alloys are of prime interest in the semiconductor industry. The article discusses copper CMP and tungsten CMP in detail and analyzes polishing mechanism during CMP by application of direct current potentiodynamic polarization and alternating current impedance measurements. It concludes with information on chemically induced defects such as pitting corrosion, galvanic corrosion, and chemical etching.

Unexpected and frequently costly failures occur due to the lack of sound and reliable engineering design. Therefore, designing against corrosion is essential for reducing such failures. This article provides a discussion on design considerations and general corrosion awareness. It details the functional requirements, such as design and materials selection, which assist in controlling corrosion in different environments. The article also illustrates the design factors that accelerate corrosion.

Independent verification of coating system performance can be based on laboratory testing and/or field exposure. Qualification testing is a critical component to coating system selection. This article focuses on performance evaluations that are used to prequalify coating systems, namely, facility-specific, industry-specific, coating-type-specific, or a combination of these. It describes the standard laboratory tests used to generate performance data, namely, physical, compositional, chemical exposure, and application characteristics tests. The pros and cons of using manufacturer-generated data versus independently generated data are discussed. The article provides information on accelerated corrosion/weathering testing and nuclear level 1/level 2 service coatings qualification. It also describes the procedures for establishing minimum performance requirements and for determining when requalification testing may be required.

Stray current can be defined as a current in structures that are underground or immersed in an electrolyte that most often accelerate corrosion on a structure where a positive current leaves the structure to enter the earth or an electrolyte. This article provides a description of the principles of stray current and a discussion on the major types of stray current and their properties and prediction methods. It discusses the consequences of stray current and describes the interference tests used for mapping the path of the stray currents. The article also highlights the methods of mitigating the source of stray current.

This article presents a discussion on the U.S army's position on corrosion control for wheeled tactical vehicles. It addresses the army requirement for corrosion control. The U.S. Army Tank-automotive and Armaments Command (TACOM) defines the corrosion prevention and control requirements in the procurement document. The article summarizes requirements from a procurement document. As required by the procurement contract, corrosion-control technologies used in a vehicle system need to be evaluated to determine their benefit. The article provides information on testing systems, which help to meet the army's needs. It includes information on supplemental corrosion protection, which improves the corrosion resistance of a material.

Stray-current corrosion is an accelerated form of corrosion caused by externally induced electric current. It can occur in unprotected pipelines and submerged metal structures located near electric power sources or anywhere voltage differences exist. This article describes common scenarios and sources of stray current along with ways to detect it and prevent the type of corrosion it can cause.

This article discusses corrosion resistance of titanium and titanium alloys to different types of corrosion, including galvanic corrosion, crevice corrosion, stress-corrosion cracking (SCC), erosion-corrosion, cavitation, hot salt corrosion, accelerated crack propagation, and solid and liquid metal embrittlement. A short section discusses the addition of alloys that can improve the corrosion resistance of titanium.

This article addresses the major heat-transfer components of the water-steam loop of a power plant. It describes the various types of condensers, including water-cooled condensers and air-cooled condensers. The article explains the corrosion mechanisms encountered in the condensers, including erosion-corrosion, galvanic corrosion, and pitting corrosion. It discusses the types of deaerators and deals with their corrosion problems. The article provides a discussion on two types of feedwater heaters: channel feedwater heaters and header feedwater heaters. It summarizes the corrosion problems associated with common feedwater heater tube materials.