Search Results for concentrated sulfuric acid

This article describes the selection of materials for the production and handling equipment of concentrated sulfuric acid, depending on factors such as the allowable corrosion rate, desired mechanical and physical properties, fabrication requirements, availability, and cost. Materials such as carbon steel, cast irons, austenitic stainless steels, higher austenitic stainless steels, higher chromium Fe-Ni-Mo alloys, nickel-base alloys, non-metals, and specific other metals and alloys are also discussed.

This article presents a summary of the chemical fundamentals, general techniques, limitations, and applications of chemical spot testing as well as a brief overview of innovations and specialized applications. A list of selected reagents, including abbreviated instructions for preparing the reagent solution(s), for performing the spot test, and for interpreting the results, is also included. The article discusses two specialized applications of qualitative analysis, namely illicit drug identification and spacecraft drinking water quality testing. It also contains tables listing common presumptive tests for detecting anions and cations in aqueous solution.

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.

The sealing of the anodized aluminum is a critical process in achieving the durability and extended functionality of anodizing. This article discusses the different methods for sealing the anodic coatings produced by using sulfuric acid, namely, hot deionized water, hot nickel acetate, midtemperature, cold, and dichromate sealing. It reviews the factors that affect seal quality: immersion time, chemistry concentration, temperature, pH, water quality, coating thickness, and contaminants/dye bleeding. The article describes the various tests that are used for determining the quality of the seal, namely, salt spray, modified dye stain, acid dissolution, impedance, copper accelerated acetic acid salt spray, high-alkaline resistance, SO 2 fog, and clorox tests.

Pickling is the most common of several processes used to remove scale from steel surfaces. This article provides a discussion on pickling solutions, such as sulfuric and hydrochloric acid, and describes the role of inhibitors in acid pickling. It discusses the equipment and processes involved in the batch, continuous, and electrolytic pickling of carbon steel components. The article describes the effects of process variables on scale removal in sulfuric and hydrochloric acid. It concludes with a description of pickling defects, spent pickle liquor disposal, and safety practices.

This article provides a description of the classification, industrial applications, microstructures, physical, chemical, corrosion, and mechanical properties of zirconium and its alloys. It discusses the formation of oxide films and the effects of water, temperature, and pH on zirconium. The delayed hydride cracking of zirconium is also described. The article provides information on the resistance of zirconium to various types of corrosion, including pitting corrosion, crevice corrosion, intergranular corrosion, galvanic corrosion, microbiologically induced corrosion, erosion-corrosion, and fretting corrosion. The article explains the effects of tin content in zirconium and effects of fabrication on corrosion. Corrosion control measures for all types of corrosion are also highlighted. The article concludes with information on the safety precautions associated with handling of zirconium.

This article describes the resin and fabrication requirements associated with fiberglass-reinforced plastic equipment. It provides a discussion on various resins and their resistance to various environments. These include polyester, epoxy, epoxy vinyl-ester, and furan and phenolic thermosetting resins. The article concludes with a discussion on the curing system of thermosetting resins.

Cast irons provide excellent resistance to a wide range of corrosion environments when properly matched with that service environment. This article presents basic parameters to be considered before selecting cast irons for corrosion services. Alloying elements can play a dominant role in the susceptibility of cast irons to corrosion attack. The article discusses the various alloying elements, such as silicon, nickel, chromium, copper, and molybdenum, that enhance the corrosion resistance of cast irons. Cast irons exhibit the same general forms of corrosion as other metals and alloys. The article reviews the various forms of corrosions, such as graphitic corrosion, fretting corrosion, pitting and crevice corrosion, intergranular attack, erosion-corrosion, microbiologically induced corrosion, and stress-corrosion cracking. It discusses the four general categories of coatings used on cast irons to enhance corrosion resistance: metallic, organic, conversion, and enamel coatings.

Tantalum is one of the most versatile corrosion-resistant metals known. The outstanding corrosion resistance and inertness of tantalum are attributed to a very thin, impervious, protective oxide film that forms on exposure of the metal to slightly anodic or oxidizing conditions. This article provides a discussion on the mechanism of corrosion resistance and on the behavior of tantalum in different corrosive environments, namely, acids; salts; organic compounds; reagents, foods, and pharmaceuticals; body fluids and tissues; and gases. It contains several tables that summarize the effects of acids, salts, and miscellaneous corrosive reagents on tantalum and applications for tantalum equipment in chemical, pharmaceutical, and other industries. Finally, the article presents a discussion on hydrogen embrittlement, the galvanic effects, and cathodic protection of tantalum and describes the corrosion resistance of different types of tantalum-base alloys.

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.

Nickel and nickel-base alloys are vitally important to modern industry because of their ability to withstand a wide variety of severe operating conditions involving corrosive environments, high temperatures, high stresses, and combinations of these factors. This article discusses the mining and extraction of nickel and describes the uses of nickel. It discusses the categories of nickel-base alloys, including wrought corrosion-resistant alloys, cast corrosion-resistant alloys, heat-resistant alloys (superalloys), and special-purpose alloys. The article covers the corrosion resistance of nickel with the inclusion of varying alloying elements. It provides useful information on the behavior of nickel and nickel alloys in specific environments describes its corrosion resistance in certain acids, alkalis, and salts.

Nitric acid is a strongly oxidizing acid that is aggressively corrosive to many metals. Its oxidizing nature is affected by acid temperature and concentration, and composition of the alloy exposed to it. This article focuses on the corrosion behavior of various ferrous and nonferrous metals and alloys when exposed to a nitric acid environment. The ferrous and nonferrous metals and alloys discussed are carbon and alloy steels, stainless steels, aluminum alloys, titanium, zirconium alloys, niobium and tantalum, and nonmetallic materials.

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 provides an overview of the degradation of metals and alloys in aqueous systems. The importance of the hydrogen ion lies in its ability to interact with an alloy surface. The article describes the effects of various conditions of pH on corrosion including strongly acid conditions, near-neutral conditions, and strongly basic conditions as well as the effects of temperature on corrosion. The influence of the fluid flow rate on corrosion depends on the alloy, fluid components, fluid physical properties, geometry in which the fluid is contained, and corrosion mechanism. The article discusses the influence of fluid flow rate through specific examples. It concludes with information on how the concentration of dissolved species works with other variables to influence corrosion behavior.

This article describes the safety precautions required for using laboratory equipment. It reviews the various personal protective equipment specified on the Material Safety Data Sheets (MSDS) for laboratory chemicals and products. The article provides information on the storage and handling of etchants, solvents, acids, bases, and other chemicals. It describes the safety precautions and procedures for handling concentrated and dilute hydrofluoric acid. The article concludes with a discussion on the precautions to be followed in the event of spills and cleanup.

Stainless steels and nickel-base alloys are recognized for their resistance to general corrosion and other categories of corrosion. This article examines the effects of specific alloying elements, metallurgical structure, and mechanical conditioning on corrosion resistance of these materials. It provides information on the compositions of selected stainless steels, copper-nickel, and nickel-base alloys in a tabular form. The article also illustrates the compositional and property linkages for stainless steels and nickel-base alloys.

This article discusses surface engineering of nonferrous metals including aluminum and aluminum alloys, copper and copper alloys, magnesium alloys, nickel and nickel alloys, titanium and titanium alloys, zirconium and hafnium, zinc alloys, and refractory metals and alloys. It describes various techniques to improve functional surface properties and enhance the appearance of product forms. The article discusses various cleaning and finishing techniques such as abrasive blast cleaning, polishing and buffing, barrel burnishing, chemical cleaning, pickling, etching and bright dipping, electrochemical cleaning, mechanical cleaning, and mass finishing. It also examines coating processes such as plating, anodizing, chemical conversion coating, and thermal spray, and concludes with a discussion on oxidation-resistant coatings for refractory metals.