Search Results for chemical and process industries

Understanding the high-temperature corrosion behavior of alloys is an important step toward the selection of appropriate alloys for process equipment. This article briefly describes the high-temperature corrosion modes that are frequently encountered in the chemical process industry. These modes include oxidation, carburization, metal dusting, nitridation, halogen corrosion, and sulfidation.

Mixtures of acids or acids and salts are of great importance to the chemical process industry (CPI) for use in digestion of solids, as a promoter in reactions, as a scale remover, and as a complexant. This article emphasizes the assessment of the performance of Ni-Fe-Cr-Mo alloys in mixed acids and salts in an objective manner. It tabulates the nominal compositions of pertinent Ni-Fe-Cr-Mo corrosion-resistant alloys. The article describes the acid and acid-plus-salt mixtures classified into the following general categories: nonoxidizing acid mixtures (H 2 SO 4 +H 3 PO 4 ), nonoxidizing acids with halides (H 2 SO 4 +HCl), oxidizing acid mixtures without halides (H 2 SO 4 +HNO 3 ), and oxidizing acid mixtures with halides (HNO 3 +HF). It also illustrates the effect of alloying elements on the corrosion rate in the nonoxidizing mixtures and oxidizing acid mixtures.

Natural and synthetic rubber linings are used extensively in many industries for their corrosion and/or abrasion resistance. These industries include transportation, chemical processing, water treatment, power, mineral processing, and mining. This article provides information on soft natural rubber, semihard natural rubber, hard natural rubber, neoprene or polychloroprene, chlorobutyl, three-ply linings, nitrile, and ethylene propylene with a diene monomer. Emphasis is placed on advantages, disadvantages, and common uses of each material discussed.

This article focuses on noble and neutral coatings and the requirements necessary to achieve successful industrial applications. These include corrosion and wear control and repair applications in processing and chemical industries, and valve and downhole drilling applications in the petrochemical industry. The article also discusses substrate chemistry and preparation; coating selection process and microstructure; sealing by chemical, post-heat treatments, and laser processing; and thermal spray process alternatives.

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 provides a summary of the concepts discussed in the Section “Corrosion in Specific Industries” in the ASM Handbook, Volume 13C:Corrosion: Environments and Industries. This Section applies the fundamental understanding of corrosion and knowledge of materials of construction to practical applications. The industries addressed are nuclear power, fossil and alternative fuel, land transportation, air transportation, microelectronics, chemical processing, pulp and paper, food and beverage, pharmaceutical and medical technology, petroleum and petrochemical, building, and mining and metal processing.

This article discusses the corrosion characteristics of superaustenitic stainless and duplex stainless steels, which are used in pharmaceutical industry. It describes passivation treatments and the electropolishing of stainless steels. The article informs that electropolishing is not a passivation treatment, although the proper execution of the process will result in a passive surface. The article concludes with a discussion on roughing, which is a phenomenon of particular interest to the pharmaceutical industry.

Titanium has been recognized as an element with good mechanical and physical properties, alloying characteristics, and corrosion resistance. Providing an outline of general characteristics and types of titanium alloys, this article discusses the contemporary technology of titanium along with its market developments. It also discusses the application of titanium and titanium alloys in corrosive environments and in aerospace and automotive industries. The article describes the developments in titanium processing and materials technologies, which include the development of sponge production and melting processes, oxide dispersion-strengthened alloys by powder metallurgy techniques, titanium-base intermetallic compounds, and titanium-matrix composites.

This article discusses the weldability characteristics of cobalt-base corrosion-resistant (CR) alloys, titanium-base CR alloys, zirconium-base CR alloys, and tantalum-base CR alloys that assist in the selection of suitable alloy and welding method for producing high-quality welds.

Phosphoric acid is less corrosive than sulfuric and hydrochloric acids. This article discusses the corrosion rates of metal alloys in phosphoric acid, including aluminum, carbon steel and cast irons, stainless steels, nickel-rich G-type alloys, copper and copper alloys, nickel alloys, lead, titanium alloys, and zirconium alloys. Nonmetallic materials may be chemically attacked in some corrosive environments, which can result in swelling, hardening, or softening phenomena; extraction of ingredients; chemical conversion of the nonmetallic constituents; cross-linking oxidation; and/or substitution reactions. The article also describes the corrosion resistance of nonmetallic materials such as rubber and elastomeric materials, plastics, carbon and graphite, and ceramic materials.

Low-alloy steels are used in a broad spectrum of applications. In some cases, corrosion resistance is a major factor in alloy selection; in other applications, it is only a minor consideration. This article reviews the applications of alloy steel products in four major industries, namely, oil and gas production, energy conversion systems, marine applications, and chemical processing. Emphasis is placed on the corrosion characteristics of the products, which are used in various applications of each industry.

Improvement in the corrosion performance of a component or structure can be achieved through proper design, surface protection, proper material selection, or combinations of all three parameters. This is an introductory article on the selection of nonferrous corrosion-resistant materials.

Stainless steels are an important class of engineering alloys used in both wrought and cast form for a wide range of applications and in many environments. This article aids in the selection of stainless steels based on weldability and service integrity. Stainless steels are classified by microstructure and are described as ferritic, martensitic, austenitic, or duplex. The article illustrates compositional ranges of the ferritic, martensitic, austenitic, and duplex alloys in the Schaeffler diagram. It describes the metallurgical aspects of welded stainless steels to be considered for particular engineering applications and service conditions. The article discusses the microstructural evolution of the weld metal and the heat-affected zone, susceptibility to defect formation during welding, mechanical and corrosion properties, and weld process tolerance.

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.

This article describes the processes involved in the production of hafnium and its alloys. It discusses the physical, mechanical and chemical properties of hafnium. The aqueous corrosion testing of hafnium and its alloys is detailed. The article reviews the corrosion resistance of hafnium in specific media, namely, water, steam, hydrochloric acid, nitric acid, sulfuric acid, alkalis, organics, molten metals, and gases. Forms of corrosion, namely, galvanic corrosion, crevice corrosion, and pitting corrosion are included. The article explains the corrosion of hafnium alloys such as hafnium-zirconium alloys and hafnium-tantalum alloys. It also deals with the applications of hafnium and its alloys in the nuclear and chemical industries.

This article provides a detailed discussion on the corrosion of steel and stainless steel under insulation. Stress corrosion cracking mechanism, types of alloys susceptible to corrosion, factors influencing corrosion, and corrosion prevention methods, are also discussed.

Organic acids represent a key group of industrial chemicals. This article provides information on the corrosion characteristics of organic acids. It focuses on corrosion caused by acetic, formic, and propionic acids on various metals and alloy groups. These include steel, aluminum, copper and its alloys, stainless steels, titanium, and nickel alloys. The article also provides information on longer-chain organic acids.

This article addresses several distinct aspects of corrosion that should be taken into account when solving the corrosion problems in the food and beverage industries. It summarizes the role of international standards in developing food and beverage industries: the American Society of Mechanical Engineers (ASME), American Welding Society (AWS), and Food and Drug Administration (FDA). The article tabulates the approximate pH values of various foods. It describes the contamination of food products by corrosion. A discussion on specific stainless steels, their corrosion resistance, fabrication, and applications is presented and compared to other potential materials of construction. The article also presents case studies of stainless steel corrosion and concludes with a discussion on corrosion in cleaning and sanitizing processes.

This article discusses the welding characteristics, welding metallurgy, and postweld heat treatment process of nickel-base corrosion-resistant alloys containing molybdenum. It contains tables that provide information on the nominal chemical compositions and physical properties of the alloys.