Search Results for hydrogen permeation

This article explores the use of the electrochemical and nonelectrochemical techniques for measuring the corrosion behavior of buried metals and the types of probes used. The electrical resistance technique is the main nonelectrochemical technique used for measuring corrosion rate. Electrochemical techniques discussed include linear polarization resistance, electrochemical noise, harmonic distortion analysis, electrochemical impedance spectroscopy, and hydrogen permeation. The principles of operation for the corrosion measuring techniques are described along with examples of their use in soils.

This article discusses the environmental influences on protective coating films that can result in deterioration. These environmental factors can be classified into four groups: (1) energy: solar, heat; (2) permeation: moisture, solvent, chemical, and gas; (3) stress: drying and curing-internal stress, and vibration-external stress; and (4) biological influences such as microbiological, mildew, and marine fouling.

This article reviews the fundamentals of electrochemical corrosion test methods. The features and requirements of the instrumentation needed for an electrochemical test are briefly discussed. The article provides a discussion on the various electrochemical techniques and tests available for laboratory studies of corrosion phenomena. The techniques and tests include no-applied-signal tests, small-signal polarization tests, large-signal polarization tests, scanning electrode techniques, and miscellaneous techniques.

Paints and protective coatings are the most common means of protecting materials from deterioration. This article focuses on coating degradation that results from the environmental interaction with the coatings. The major environmental influences of the degradation include energy (solar radiation, heat and temperature variation, and nuclear radiation), permeation (moisture, solvent retention, chemical, and oxygen), stress (drying and curing, vibration, and impact and abrasion), and biological influences (microbiological and macrobiological).

Hydrogen damage is a form of environmentally assisted failure that results from the combined action of hydrogen and residual or applied tensile stress. This article classifies the various forms of hydrogen damage and summarizes the theories that seek to explain these types of degradation. It reviews hydrogen degradation in specific ferrous and nonferrous alloys, namely, iron-base alloys, nickel alloys, aluminum alloys, copper alloys, titanium alloys, zirconium alloys, and vanadium, niobium, tantalum, and their alloys. An outline of hydrogen damage in intermetallic compounds is also provided.

This article focuses on epoxy because this resin category has widespread use and because it is tested using quality control measures typical of most resin systems. It explains that a typical resin system will consist of one or more epoxy resins, a curing agent, and a catalyst to control the rate of reaction. The article describes the component material tests, mixed resin system tests, and prepreg tests for the resin system. These tests include high-performance liquid chromatography, infrared spectroscopy, and gel permeation chromatography. The article contains a table that lists typical resin and prepreg property tests.

This article provides the corrosion data for materials in hydrofluoric acid (HF) and anhydrous hydrogen fluoride (AHF). These materials include carbon and low-alloy steels, austenitic stainless steels, nickel-rich austenitic stainless steels, nickel and nickel-base alloys, copper alloys, precious metals, and non-metals. The article also discusses the hydrogen blistering and stress-corrosion cracking of carbon steels in high-temperature HF and AHF.

Elastomers belong to a group of materials known as polymers that acquire their properties and strength from their molecular weight, chain entanglements, and crystalline regions. This article focuses on the use of elastomers as seals and describes its performance capabilities from the point of a sealant. The important technical concepts that define the performance capabilities of the elastomeric part include polymer architecture (molecular building blocks), compounding (the ingredients within the polymer), and vulcanization of the elastomer shape. The article discusses the aggressiveness of the chemical environment, temperature, and minor constituents in the environment and in the material itself that affect the chemical resistance of the elastomer. It provides a discussion on performance evaluation methods, namely, immersion testing and application specific testing that are determined using ISO and ASTM standards. The article concludes with information on elastomer failure modes and failure analysis.

This article outlines the processes by which materials are selected to prevent or control localized corrosion, galvanic corrosion, and intergranular corrosion. It reviews the operating conditions and the design of candidate materials for material selection. The article discusses various corrosion-resistant materials, including ferrous and nonferrous metals and alloys, thermoplastics, reinforced thermosetting plastics, nonmetallic linings, glass, carbon and graphite, and catalyzed resin coatings. It examines an unusual form of intergranular corrosion known as exfoliation, which occurs in aluminum-copper alloys. The article also describes three types of erosion-corrosion: liquid erosion-corrosion, cavitation, and fretting. It concludes with information on the various factors to be considered for material selection, including minimum cost or economic design, minimum corrosion, minimum investment, and minimum maintenance.

This article focuses on the subject of proactive or predictive maintenance with particular emphasis on the control and prediction of corrosion damage for life extension and failure prevention. It discusses creep life assessment from the perspective of creep-rupture properties and creepcrack growth. Practical methods based on replication and parametric approaches are also discussed.

This article discusses the corrosion of metals and nonmetals by dry chlorine, refrigerated liquid chlorine, dry gaseous chlorine, moist chlorine, selected mixed gases with chlorine, and chlorine-water. It also provides information on the handling of commercial chlorine.

This article focuses on the mechanisms of microbially induced or influenced corrosion (MIC) of metallic materials as an introduction to the recognition, management, and prevention of microbiological corrosion failures in piping, tanks, heat exchangers, and cooling towers. It discusses the degradation of various protective systems, such as corrosion inhibitors and lubricants. The article describes the failure analysis of steel, iron, copper, aluminum, and their alloys. It also discusses the probes available to monitor conditions relevant to MIC in industrial systems and the sampling and analysis of conditions usually achieved by the installation of removable coupons in the target system. The article also explains the prevention and control strategies of MIC in industrial systems.

Nuclear power plants benefit from thermal spray coatings for corrosion and erosion minimization and dimensional restoration of worn parts. This article provides a detailed discussion on the advantages of thermal spray coatings, fission reactor component coatings, and coatings for nuclear fuel processing before and after irradiation for power plant applications. Nuclear fusion research is divided into two primary fields of study categorized by the method for confining the fusion fuel: magnetic confinement fusion and inertial confinement fusion.

Mechanical plating is a method for coating ferrous metals, copper alloys, lead, stainless steel, and certain types of castings by tumbling the parts in a mixture of glass beads, metallic dust or powder, promoter or accelerator chemicals, and water. It offers a straightforward alternative method for achieving desired mechanical and galvanic properties with an extremely low risk of hydrogen embrittlement. This article provides a detailed description of the equipment, process steps, process capabilities, applicable parts, specific characteristics, advantages, limitations, post treatments, and waste treatment of mechanical plating.

This article focuses on the mechanisms of microbiologically influenced corrosion as a basis for discussion on the diagnosis, management, and prevention of biological corrosion failures in piping, tanks, heat exchangers, and cooling towers. It begins with an overview of the scope of microbial activity and the corrosion process. Then, various mechanisms that influence corrosion in microorganisms are discussed. The focus is on the incremental activities needed to assess the role played by microorganisms, if any, in the overall scenario. The article presents a case study that illustrates opportunities to improve operating processes and procedures related to the management of system integrity. Industry experience with corrosion-resistant alloys of steel, copper, and aluminum is reviewed. The article ends with a discussion on monitoring and preventing microbiologically influenced corrosion failures.

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 use of gases or molten salts as the quenchant for steel parts is commonly limited to the quenching of high-alloy steel or the carbonizing quenching of low-alloy steel. This article reviews the quenching process of steels with molten metals (quenchant) such as molten lead, molten bismuth, and molten sodium. It also contains tables that list the physical properties of lead, bismuth, sodium, and molten sodium.

This article provides an overview of plasma surface treatments for plastics. It covers the equipment and methods used in plasma processing, providing detailed explanations of the plasma discharge reactions and how they affect surface state and topography. It also provides information on contamination removal, plasma surface modification, plasma-induced grafting, and plasma film deposition.