Several qualitative, semiquantitative, and quantitative tests are available to estimate and control metal cleanliness, particularly inclusion concentration of aluminum alloys. This article provides a description of a few of the metal cleanliness assessment techniques, such as chemical analysis, pressure filter tests, electric resistivity tests, reduced-pressure test, and ultrasonic technique. Detection methods based on the certain principles and the types of impurities in chemical analysis are discussed.

This article addresses electrical testing and characterization of plastics and presents a number of techniques for evaluating the electrical properties of insulating materials, with a special focus on plastics, accompanied by a list of the electrical properties of different types of plastics. It provides the reader with sufficient information to select the appropriate electrical test(s) for a specific application. The tests covered in this article are widely used in industry to determine the electrical properties of insulating materials, particularly plastics. The article lists and defines terms used in connection with testing and specification of plastics for electrical applications.

In terms of their electrical properties, plastics can be divided into thermosetting and thermoplastic materials, some of which are conductive or semiconductive. This article provides detailed information on factors that affect the property of plastics. It discusses the major test methods used to determine the following dielectric properties of plastics: dielectric breakdown voltage, dielectric strength, dielectric constant, dissipation factor, arc tracking resistance, insulation resistance, volume, and surface resistivity or conductivity. The test specifications and conditions, recommended by several U.S. and foreign testing organizations for characterizing the electrical properties of plastic materials are listed. The article describes the influence of these properties on selection of plastics for insulation application. An outline of the electromagnetic shielding and testing methods of electromagnetic interference are also provided. Designations, electrical properties, and applications of elastomers are tabulated.

Galvanic corrosion, although listed as one of the forms of corrosion, is considered as a type of corrosion mechanism that is evaluated by modifying the tests used for conventional forms of corrosion. This article focuses on component testing, computer and physical scale modeling, and laboratory testing methods of evaluating galvanic corrosion. The laboratory tests fall into two categories, namely, electrochemical tests and specimen exposures.

This article describes the test methods for evaluating the durability of a metal in soil. It provides useful information on soil characteristics such as soil electrical resistivity, pH value, and soil texture. Specimen design, preparation, burial, and retrieval techniques are discussed. The type of information sought during soil-induced corrosion evaluation controls the design configuration and the nature of the corrosion measurements. Consideration of these factors during the planning stage helps the corrosion engineer to obtain the maximum amount of information with the minimum number of problems.

This article presents the fundamentals of stray-current corrosion caused by electric rail transit systems. It describes the various corrosion-control design elements for the electric rail system. These design elements include substation spacing and grounding, track and track slab design, and construction acceptance criteria. The impacts of the electric rail construction in underground utilities are discussed. Direct physical interferences, maintenance access encroachments, stray-current effects, and utility relocation design considerations, are discussed. The article also reviews construction issues such as funding, sequencing, and working clearances. It concludes with information on the post-construction monitoring and maintenance for stray-current corrosion control.

This article provides information on predesign surveys and the various testing procedures associated with wastewater treatment plants. These include soil testing, atmospheric testing, and hydrogen sulfide testing. The primary parameters that influence the production of sulfides within the piping system that transports the wastewater to the treatment facility are discussed. The article describes the corrosion performance of various materials in the soil, fluid, and atmospheric exposures. These include concrete, steel, ductile iron, aluminum, copper, brass, stainless steel, and coatings used for wastewater facilities.

Heat treatment of aluminum alloys is assessed by various quality-assurance methods that include metallographic examination, hardness measurements, mechanical property tests, corrosion-resistance tests, and electrical conductivity testing. The use of hardness measurements in the quality assurance of heat treated aluminum products is effectively used in conjunction with the measurement of surface electrical conductivity. This article provides a detailed discussion of the error sources in eddy-current conductivity measurements. It also presents useful information on the variation of electrical conductivity of alloy 2024 samples as a function of aging time at different isothermal holding temperatures.

Porcelain enamel is a fusion bonded glass coating that resists chemical and abrasive attack, provides thermal and electrical insulation, and improves aesthetic qualities. It is used on cast iron as well as steel and aluminum alloys. This article provides a review of the porcelain enameling process, the composition of frits, and the preparation of coating substrates. It also provides information on chemical, mechanical, and electrical properties and sheds light on process consistency and quality control.

This article describes the criteria for selecting a corrosion-monitoring method used in industrial plants. It provides a detailed discussion on the design, advantages, and disadvantages of plant corrosion-testing program. The basic types of racks used to support and insulate the coupons are also discussed. The analysis of electrical-resistance probes, sentry holes, side-stream loop, electrochemical noise, hydrogen-probe, and process streams are used to monitor and estimate corrosion rates. The corrosion rates can also be estimated by ultrasonic thickness measurements, polarization-resistance measurements, corrosion potential measurements, and alternating current impedance measurements. Corrosion monitoring strategies, such as locations, data analysis, redundancy, and other issues, are discussed. The article concludes with information on the interpretation and reporting of corrosion testing.

Steel storage tanks are the primary means for storing large volumes of liquids and gaseous products. The stored fluid could be water, but it could also be volatile, corrosive, and flammable fluid requiring special precautions for storage as well. Corrosion is generally worst where the tank is in contact with the soil. This article describes the soil characteristics and addresses cathodic protection (CP) criteria for submerged metallic piping systems. It provides information on the data required for designing a CP system, alone or in conjunction with a protective coating system. These data are collected from predesign site assessments, tank electrical characteristics, and soil-resistivity measurements. The article addresses NACE Standard RP0169, which gives requirements and desired characteristics for coating in conjunction with CP. It also explains the methods of protecting aboveground storage tanks and underground storage tanks.

This article focuses on the testing and typical corrosion behavior of coating-substrate systems in aqueous solutions and humid aggressive atmospheres. It includes a short review of the fundamentals of corrosion, followed by a discussion of specific system behavior, electrochemical and laboratory accelerated tests, and simulated service tests. The article also contains examples of different types of corrosion damage and presents guidelines for improving corrosion resistance.

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.

Electrical resistance alloys include those types used in instruments, control equipment, heating elements, and devices that convert heat generated to mechanical energy. This article discusses the basic classification of electrical resistance alloys (resistance alloys, heating alloys, and thermostat metals), their subtypes, properties, service life, and operating temperatures. It describes the designing and fabrication of open resistance and sheathed heaters. The article contains a collection of tables and graphs that provide information on the mechanical properties, chemical composition, temperature coefficient of resistance, furnace operating temperatures, length and spacing of loops, ribbon size, and electrical capacity of heating elements.

Corrosion monitoring is important in the operation of modern industrial plants and in the use and maintenance of expensive assets such as bridges and aircrafts, because the damage caused by corrosion and the rate of the deterioration can be huge and the risks devastating. This article discusses the system considerations and installation techniques of different types of direct and indirect techniques in electrochemically based on-line corrosion monitoring process. It describes the importance of probe location and on-line corrosion monitoring techniques with examples.

This article presents the structural attributes and internal characteristics of spot welds as well as the commonly inspected imperfections in resistance welds. It describes the industrial requirements for weld quality. Commonly performed destructive evaluations, namely, manual testing, quasi-static mechanical tests, dynamic mechanical tests, and metallographic examination, are reviewed. The article reviews weld-quality monitoring using various process signals and provides a discussion on the on-line and off-line nondestructive evaluation methods of spot weld quality.

Electrical contacts are metal devices that make and break electrical circuits. This article provides information on materials selection criteria and failure modes of make-break contacts. It describes the property requirements for make-break arcing contacts, namely, electrical conductivity, mechanical properties, chemical properties, fabrication properties, and thermal properties. The article presents a brief note on brush contact materials and their interdependence factors for sliding contacts. It also describes the type of commercial contact materials for electrical contacts, namely, copper metals, silver metals, gold metals, metals of the platinum group, precious metal overlays, tungsten and molybdenum, aluminum, and composite materials. Finally, the article provides information on composite manufacturing methods, and tabulates the physical, and mechanical properties of electrical contact materials, including copper, silver, gold, platinum, palladium, and composites.

This article provides an overview of the various types of unsaturated polyester resins and low-profile additives. The resins include general-purpose resins, isophthalic resins, bisphenol A fumarate resins, chlorendic resins, and vinyl ester resin. The article describes the mechanical and electrical properties, thermal and oxidative stability, and chemical and ultraviolet (UV) resistance of polyester resins. It concludes with a discussion on the flame-retardant polyester resins.

Engineering plastics offer unique product benefits based on physical properties, or combinations of physical properties, that allow vastly improved product performance. Providing an overview of the general characteristics and the mechanical and environmental stress response of engineering plastics, this article discusses various factors, including thermal, mechanical and electrical properties, environmental factors, and material cost that are important in the selection of engineering plastics for specific applications.

This article describes weathering and environmental factors that contribute to degradation in plastics, including temperature variations, moisture, sunlight, oxidation, microbiologic attack, and other environmental elements. It presents a general overview of aging factors, their effects on plastic materials, and the accelerated test methods that can be used to estimate the reaction of a plastic component during actual use. The article focuses on the determination of service temperature as it indicates the ability of a material to retain a certain property, when exposed to elevated temperatures for an extended period of time. It concludes by describing various degradation processes, namely, thermal degradation, thermal oxidative degradation, photooxidative degradation, environmental corrosion, and chemical corrosion and discussing the ways of detecting these degradation processes.