Search Results for crude metals

Electrochemical refining is the purification process for producing commercially pure metals from crude metals. This article describes the principles of electrochemical reactions. It discusses the physical properties of the basic components of electrochemical refining cell. The article also explains the engineering considerations required in the refining process. Theoretical and technological principles of electrochemical refining are illustrated, with examples.

This article provides useful information on the occurrence of corrosion in crude oil refinery units, namely, crude unit, catalytic and thermal cracking units, hydroprocessing units, amine sweetening units, and sour water units. Types and applications of corrosion inhibitors, namely, neutralizers, filming inhibitors, scavengers, microbiocides, and anti-foulants and scale inhibitors, are reviewed. The article describes the direct and indirect corrosion monitoring methods used to reduce equipment damage due to corrosion events and to assess the reliability and useful service life of process equipment.

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.

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.

Gallium-base components can be found in a variety of products ranging from compact disk players to advanced military electronic warfare systems, owing to the factor that it can emit light, has a greater resistance to radiation and operates at faster speeds and higher temperatures. This article discusses the uses of gallium in optoelectronic devices and integrated circuits and applications of gallium. The article discusses the properties and grades of gallium arsenide and also provides information on resources of gallium. The article talks about the recovery techniques, including recovery from bauxite, zinc ore and secondary recovery process and purification. The article briefly describes the fabrication process of gallium arsenide crystals. Furthermore, the article gives a short note on world supply and demand of gallium and concludes with research and development on gallium arsenide integrated circuits.

This article discusses the effects of parameters on corrosivity and explains why it is critical to examine the parameter interactions prior to capturing the synergistic effects of the parameters on corrosion. It examines the methods of internal corrosion prediction for multiphase pipelines. The article reviews methodologies to perform internal corrosion direct assessment for pipelines. Real-time monitoring techniques for assessing actual corrosion at critical locations are discussed. The article also presents the case studies for multi-technique electrochemical corrosion monitoring.

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 analyzes the estimates of the cost of corrosion, made in various countries at various times. The data are extrapolated to a 2004 base and then projected to the global economy. The chronological order of the countries are the United States of America, the United Kingdom, Australia, Japan, Canada, Germany, Poland, South Africa, Czechoslovakia, Belgium, Netherlands, Sweden, Finland, the Union of Soviet Socialist Republics, Kuwait, India, and the Basque Region.

Zirconium, hafnium, and titanium are produced from ore that generally is found in a heavy beach sand containing zircon, rutile, and ilmenite. This article discusses the processing methods of these metals, namely, liquid-liquid separation process, distillation separation process, refining, and melting. It also discusses the primary and secondary fabrication of zirconium and hafnium and its alloys. The article talks about the metallurgy of zirconium and its alloys with emphasis on allotropic transformation, cold work and recrystallization, anisotropy and preferred orientation, and the role of oxygen. It concludes by providing useful information on the applications of reactor and industrial grades of zirconium alloys.

This article discusses the general characteristics, primary and secondary fabrication methods, product forms, and corrosion resistance of zirconium and hafnium. It describes the physical metallurgy of zirconium and its alloys, providing details on allotropic transformation and anisotropy that profoundly influences the engineering properties of zirconium and its alloys. Tables listing the values for chemical composition and tensile properties for nuclear and nonnuclear grades of zirconium are also provided.

This article describes the coating materials, surface-preparation requirements, and application techniques used to protect underground pipelines. It provides a valuable insight into the types of polymer-based coatings that are both cost-effective and widely accepted in the pipeline industry.

This article discusses fractures and cracks due to ancient artifact weaknesses. It provides several case studies to aid the appreciation of fractography as a diagnostic technique and to understand the importance of cracking. These case histories concern ancient gold and silver alloys, bronzes, and wrought irons. The article considers the applicabilities of fractography, metallography, and chemical analyses in answering archaeological and archaeometallurgical questions. The article also discusses the restoration and conservation of corroded and embrittled artifacts, including the use of coatings.

The inhibitors currently in use are generally complex mixtures of reaction products and have been formulated to meet the demands of a very competitive industry. This article discusses these demands on inhibitor formulation. The varying characteristics and number of organic inhibitors are explained by the varying characteristics of oil wells and gas wells. Water injection systems and pipelines are also discussed. The article describes the factors that influence the corrosivity of produced fluids and the various treatments applicable for oil, gas, and pumping wells. It examines the primary causes of corrosion inhibition in waterfloods: oxygen contamination and acid gases dissolved in the brine. A discussion on the bacteria-induced corrosion is provided. The article also explains various tests available for field corrosion monitoring. It details the methods used to monitor corrosion rates and inhibitor effectiveness. The article concludes information on the computerization of inhibitor treating programs.

This article provides an overview of the independent and dependent variables of a machining process. Independent variables include workpiece material, specific machining processes, and tool materials and geometry. Cutting force and power, surface finish, and tool wear and failure are some dependent variables discussed. The article also describes the relations between the input variables and process behavior.

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 discusses the methods for producing powder metallurgy (PM) nickel powders, including carbonyl process, hydrometallurgical process, hydrogen reduction process, and atomization process, as well as their applications. It describes three processes for producing nickel alloy powders: water atomization, high-pressure water atomization, and gas atomization. The article also provides information on the applications of PM hot isostatic pressing in the oil and gas industry.

Organic coatings are the principal means of corrosion control for the hulls and topsides of ships and for the splash zones on permanent offshore structures. This article describes surface preparation which is the most important consideration in determining the performance of organic coating systems. It contains a table that lists the uses and applicable standards for various surface preparation techniques. The article provides information on organic coatings in topside coating systems and reviews the importance of primers in the protection of steel substrates. It also explains the property requirements and the common types of immersion coatings.

This article summarizes the metallurgy of carbon and alloy steels, followed by discussions on their major mechanical properties, namely, static fracture toughness, dynamic fracture toughness, fatigue or sustained-load crack growth rates, and fatigue or sustained-load thresholds. It addresses fatigue crack propagation and sustained-load crack propagation, as well as the fundamental aspects of fracture in steels. The article illustrates the effects of variations in the alloy chemistry, microstructure, temperature, strain rate, and environment on various fracture toughness or crack growth rate parameters.

This article presents an introduction to brazing, including information on its mechanics, advantages, and limitations. It reviews soldering with emphasis on chronology, solder metals, and flux technology. The article also provides useful information on mass, wave, and drag soldering. It presents a table which contains information on the comparison of soldering, brazing, and welding.