Cooling towers are designed to remove heat from water in an induction system and dissipate it into the atmosphere. This article provides information on closed-loop recirculating water systems of an induction system to cool the power supply. It focuses on various types of cooling towers, namely, air-cooled heat exchangers, air-cooled heat exchangers with trim cooler, closed-circuit evaporative cooling towers, and open evaporative cooling towers. The article discusses the importance of their placement or positioning to reduce the chances of air recirculation, and concludes with a discussion on refrigerant chillers.

Hardness testing equipment is important as all results from the induction equipment are graded by the hardness testing equipment. This article includes maintenance tips and points to consider regarding hardness test equipment, power supplies, controls, programmable logic controllers, computer systems, water cooling systems, fixtures and machines, air-operated or pneumatic devices, coils, and quench systems. It also presents simple rules that need to be applied while moving the equipment from one location to another.

Heat treating furnaces require different control systems and integration for achieving optimum technical results and enabling safe operation. This article focuses on atmosphere furnaces, with some coverage on controls for vacuum furnaces. Heat treating operations require reliable monitoring and control of motion and position of various mechanical components with the help of mechanical limit switches, proximity sensors, and distance- and position-measuring devices. Using inputs from both flow meters and sensors, such as thermocouples and oxygen sensors, flow measurement control systems must be able to adjust the flow of gases for process optimization. The operator interface of a furnace-control system displays critical information such as the furnace temperature, atmosphere status, alarms, electronic chart recorders, recipe, and maintenance. A supervisory control and data-acquisition (SCADA) system is used to monitor, collect, and store data from multiple pieces of equipment.

This article provides information on the heat-source model, conduction heat-transfer model of parts and fixtures, and the radiation heat-transfer and convection heat-transfer models in a furnace. It describes the two types of furnaces used for heat treating: batch furnaces and continuous furnaces. The heating methods, such as direct-fired heating, radiant-tube heating, and electrical heating, are also discussed. Furnace temperature control is essential to ensure quality heat treatment. The article explains the operating procedure of the automatic temperature controllers used in most furnace operations. Heating simulations can be validated by comparison with measured results in full-scale furnaces. The article also presents several case studies to illustrate the use of the simulations.

Corrosion problems and materials selection for emissions control equipment can be difficult because of varied corrosive compounds present and the severe environments encountered. This article discusses the selection of materials for construction of flue gas desulfurization systems. It addresses the problems associated with materials for incinerator off-gas treatment equipment. The off-gases can be classified according to their corrosiveness as: industrial chemical, hospital, municipal solid, and sewage sludge. The article provides information on the selection of materials for the three most common types of dust collection equipment used in bulk solids processing, namely, fabric filters, electrostatic precipitators, and wet scrubbers. It also discusses a wide variety of corrosion problems encountered in chemical and pharmaceutical industries.

Furnaces are one of the most versatile types of industrial appliances that span many different areas of use. This article discusses the classification of various furnaces used in heat treating based on the mode of operation (batch-type furnaces and continuous-type furnaces), application, heating method, mode of heat transfer, type of materials handling system, and mode of waste heat recovery (recuperation and regeneration). It provides information on uniform temperature distribution, the general requirements and selection criteria for insulation materials, as well as the basic safety requirements of these furnaces.

This article presents a simple cost/pricing system that is reasonably accurate and could easily be recalculated if the yearly cost of any of the basic cost components change. Using the example of a commercial heat treating facility, the operational details are categorized as atmosphere processes, induction processes, aluminum processes, high-heat processes, and secondary processes. For the purpose of calculating the heat treatment processing cost per hour and the selling price for a piece of equipment, the costs are separated into direct costs, allocated costs, capitalized cost, and general and administrative costs. The article discusses the techniques involved in allocating costs to the group of equipment, and presents a description on the cost analysis of endothermic gas.

Vacuum heat treating consists of thermally treating metals and alloys in cylindrical steel chambers that have been pumped down to less than normal atmospheric pressure. This article provides a detailed account of the operations and designs of vacuum furnaces, discussing their pressure levels, resistance heating elements, quenching systems, work load support, pumping systems, and temperature control systems. It describes the classification of instruments used for measuring and recording pressure inside a vacuum processing chamber. Common devices include hydrostatic measuring devices and devices for measuring thermal and electrical conductivity. The article also describes the applications of the vacuum heat treating process, namely, vacuum nitriding and vacuum carburizing. Finally, it reviews the heat treating process of tool steels, stainless steels, Inconel 718, and titanium and its alloys.

Surface coatings are essential in all facilities that process nuclear materials or use nuclear fission for power generation. This article describes the coatings used in two basic types of Generation 3 nuclear reactor designs in the United States and their containment size. These reactors are the boiling water reactor (BWR) and pressurized water reactor (PWR). The article provides information on the loss-of-coolant accident (LOCA) identified as the design basis accident (DBA), which can rapidly de-water the core of an operating nuclear reactor. To avoid LOCA, both the BWR and the PWR include emergency core cooling systems. The article describes a DBA test and other coating performance parameters necessary for safety-related coating systems. It provides a detailed account of the selection criteria of coating types in a nuclear plant. The article concludes by highlighting protective coating strategies in Generation 3 Plants.

Advances in vehicle design and technology require engine coolant technology to minimize the degradation of nonmetals and prevent the corrosion of the metals in the cooling system. This article provides a detailed discussion on the functions, operation, materials, and major components of the cooling system. It discusses various forms of corrosion that occur in cooling systems, including uniform corrosion, galvanic corrosion, crevice corrosion, pitting corrosion, intergranular corrosion, erosion corrosion, and cavitation corrosion. The article presents information on engine coolant base components and inhibitors used for corrosion prevention. It reviews the coolant performance tests recommended by ASTM, SAE, and vehicle manufacturers. The article concludes with a description on the difference between light-duty automotive and heavy-duty diesel engine coolants.

Rotational molding is a simple but unique process that has the capability of producing small to large hollow items with very uniform wall thicknesses. Providing an overview of the operating principles of rotational molding, this article discusses the key selection factors, including function and property requirements for resins and additives; size, shape, design, and cost of molded parts; equipment type and size; and the type of mold to be used. Commonly used molds include cast aluminum, fabricated sheet metal, nickel deposit, machined aluminum, silicone, fiberglass, and prototype molds.

This article discusses the production of aluminum and aluminum alloy powders with emphasis on the gas atomization method and the atomizing nozzle. It illustrates the particle formation mechanism and details the requisites for particle size distribution, control, and morphology. The article presents information on the mean oxide thickness formed on atomized powders. It also describes the mechanical and physical properties of aluminum and aluminum alloy powders, as well as their applications.

Mechanical cleaning systems are used to remove contaminants of work surface by propelling abrasive materials through any of these three principal methods: airless centrifugal blast blade- or vane-type wheels; compressed air, direct-pressure dry blast nozzle systems; or compressed-air, indirect-suction (induction) wet or dry blast nozzle systems. This article focuses on the abrasive media, equipment, applications, and limitations of dry and wet blast cleaning. It discusses the health and safety precautions to be taken during mechanical cleaning.

This article focuses on various heat-treating practices, namely, normalizing, annealing, stress relieving, preheating, austenitizing, quenching, tempering, and nitriding for cold-work tool steels. The cold-work tool steels include medium-alloy air-hardening tool steels, high-carbon high-chromium tool steels, and high-vanadium-powder metallurgy tool steels. The article also describes the properties, types, nominal compositions and designations of these cold-work tool steels.

Painting is a generic term for the application of a thin organic coating to the surface of a material for decorative, protective, or functional purposes. This article provides a detailed account of the types and selection factors of paints and the various application methods, including conventional air atomized, airless, and electrostatic spray; roller coating; dip coating; flow coating; curtain coating; tumble coating; electrocoating; and powder coating. Surface preparation methods and prepaint treatments for coating systems are also discussed. The article includes information on quality control procedures, causes of paint film defects, cost calculation, and safety and environmental precautions. The composition and characteristics of organic coatings, coating system selection factors, the types of paints for structural steel, and the applications of paint on structural steel are also reviewed.

This article reviews high-temperature corrosion of furnace parts used in heat-treating furnaces. It provides a comparison of cast and wrought materials in the context of their general considerations, advantages, and applications. The article provides information on the heat-resistant alloys used for parts that go through the furnaces, including trays, fixtures, conveyor chains and belts, and quenching fixtures and parts, and the parts that remain in the furnace such as combustion tubes, radiant tubes, burners, thermowells, roller and skid rails, baskets, pots, retorts, muffles, and drive and idler drums. The article also reviews the material characteristics of silicon/silicon carbide composite and reaction-bonded silicon carbide as used in radiant tubes.

This article discusses the safety issues associated with the design and operation of thermal spray booths and spray box structures and the equipment or systems required for operating thermal spray processes. It describes the design elements necessary to mitigate sound, dust and fume, ultraviolet light, and mechanical hazards. The means selected for safeguarding personnel must be based on a formal risk assessment that meets ANSI/RIA standards. The safeguards include sensing devices, barriers, awareness signals, procedures, and training. It also provides guidelines that are intended to increase the safety awareness and the use of safety practices for gas and liquid piping and electrical equipment within thermal spray installations.

Casting offers a great amount of component design flexibility. This article discusses six casting design parameters that drive the geometry of casting design from a process standpoint. It provides information on the design of junctions and addresses considerations of secondary operations in design. The article describes the factors that control casting tolerances and presents specific tips for designing castings with uniform wall thickness, unequal sections, thin sections, economical coring, functional packaging, and core design. The article provides a framework for analyzing all manners of manufacturing as possible conversion candidates for casting. It concludes with a discussion on different metalcasting design projects.

Pumps and compressors are representative fluid machineries, which are indispensably important industrial equipment for water supply systems, chemical processing and reactions, and fluid power systems. This article addresses friction, lubrication, and wear of components in several types of machines such as positive displacement pumps including hydraulic pumps, turbo-pumps including centrifugal pumps, vacuum pumps, and compressors including the positive displacement type and turbo type.