Search Results for preventive measures

This article discusses the three legal theories on which a products liability lawsuit is based and the issues of hazard, risk, and danger in the context of liability. It describes manufacturing and design defects of various products. The article explains a design that is analyzed from the human factors viewpoint and details the preventive measures of the defects, with examples. It presents four paramount questions relating to the probability of injury which are asked even when one executes all possible preventive measures carefully and thoroughly.

Magnesium alloys are used predominantly for high-pressure die-cast applications in which the use of a deliberate heat treatment is uncommon. This article provides information on the heat treatment designations for magnesium alloys. It describes the effects of grain size on magnesium alloys and the relationship between hardness and mechanical properties of the alloys. The article discusses the effects of elements such as aluminum, zinc, manganese, rare earths, and yttrium, on precipitation hardening. It describes the types of heat treatment for magnesium alloys, including annealing, stress relieving, solution treating and aging, and reheat treating. The article also discusses the preventive measures for the common problems encountered in heat treating magnesium alloys; and the evaluation of the effectiveness of heat treating procedures. In addition, it presents the processing steps involved in the heat treatment of magnesium alloys and in the prevention and control of magnesium fires.

This article discusses the principles of corrosion and the basis of the various prevention measures that can be taken for different corrosion modes. It describes aqueous corrosion phenomena in terms of the electrochemical reactions that occur at the metal-environment interface. The article explains the specific forms of corrosion, including general corrosion, localized attack, and environmentally assisted cracking. It provides a discussion on the engineering aspects of design that can, without due care and attention, precipitate unexpected premature failure. The article reviews ways to improve corrosion awareness and prevent corrosion/degradation. It describes a life prediction method with an example of environmental degradation in light-water nuclear reactors. The article concludes with a discussion on the validation of life-prediction algorithms and their applications.

The first part of this article focuses on two major forms of machining-related failures, namely machining workpiece (in-process) failures and machined part (in-service) failures. Discussion centers on machining conditions and metallurgical factors contributing to (in-process) workpiece failures, and undesired surface layers and metallurgical factors contributing to (in-service) machined part failures. The second part of the article discusses the effects of microstructure on machining failures and their preventive measures.

This article first provides an overview of the types of mechanical fasteners. This is followed by sections providing information on fastener quality and counterfeit fasteners, as well as fastener loads. Then, the article discusses common causes of fastener failures, namely environmental effects, manufacturing discrepancies, improper use, or incorrect installation. Next, it describes fastener failure origins and fretting. Types of corrosion in threaded fasteners and their preventive measures are then covered. The performance of fasteners at elevated temperatures is addressed. Further, the article discusses the types of rivet, blind fastener, and pin fastener failures. Finally, it provides information on the mechanism of fastener failures in composites.

Corrosion is the electrochemical reaction of a material and its environment. This article addresses those forms of corrosion that contribute directly to the failure of metal parts or that render them susceptible to failure by some other mechanism. Various forms of corrosion covered are galvanic corrosion, uniform corrosion, pitting, crevice corrosion, intergranular corrosion, selective leaching, and velocity-affected corrosion. In particular, mechanisms of corrosive attack for specific forms of corrosion, as well as evaluation and factors contributing to these forms, are described. These reviews of corrosion forms and mechanisms are intended to assist the reader in developing an understanding of the underlying principles of corrosion; acquiring such an understanding is the first step in recognizing and analyzing corrosion-related failures and in formulating preventive measures.

The corrosion issues in the compressor, combustor and turbine sections of industrial gas turbines used in steam production generally depend on the quality of the fuel, air, and water used in the engine than on the specific industrial application. This article focuses on the forms of corrosion and their preventive measures in the compressor, combustor and turbine sections of a steam turbine. The compressor section mainly suffers from aqueous corrosion; while in case of the combustor and turbine sections, which are made of nickel-base superalloys, high-temperature environmental attack in the form of high-temperature oxidation and hot corrosion are predominant. The effect of high-temperature oxidation and hot corrosion on the mechanical properties of superalloys is also discussed.

Coatings, such as those applied to ships, must be resistant to abrasion, in the case of cargo hold coatings, and cyclic changes of chemicals and tank cleaning, in the case of tank linings. Failures and defects can manifest themselves at various times in the life of a coating. To determine the cause and mechanism of coating failure, all possible contributory factors must be evaluated together with a detailed history from the time of application to the time the failure was first noted. Many coating failures require further evaluation and analysis to be carried out by a qualified chemist or coating specialist, often using specialized laboratory equipment. The article presents examples of coating failures and defects, together with descriptions, probable causes, and suggested preventative measures.

The crucible induction furnace is growing as an alternative melting unit to the cupola furnace due to its low specific power and reduced power consumption during solid melting material. This article details the process engineering features of the crucible induction furnace. It discusses the various processes involved in melting, holding, and pouring of liquid melt in crucible induction furnaces wherein the holding operation is carried out in channel furnace and pouring operation in pressure-actuated pouring furnaces. The article examines the behavior of furnace refractory lining to defects such as erosion, infiltration, crack formation, and clogging, and the corresponding preventive measures to avoid the occurrence of these defects. It elucidates the overall furnace operations, including commissioning, operational procedures, automatic process monitoring, inductor change, and dealing with disturbances.

Hardfacing refers to the deposition of a specially selected material onto a component in order to reduce wear in service as a preventative measure or return a worn component to its original dimensions as a repair procedure. This article provides information on various hardfacing materials, namely, iron-base overlays, chromium carbide-based overlays, nickel- and cobalt-base alloys, and tungsten carbide-based metal-matrix composite overlays. It discusses the types of hardfacing processes, such as arc welding processes, and laser cladded, oxyacetylene brazing and vacuum brazing processes. The arc welding processes include shielding metal arc welding, gas metal arc welding/flux cored arc welding, gas tungsten arc welding, submerged arc welding, and plasma transferred arc welding. The article also reviews various factors influencing the selection of the appropriate hardfacing for specific applications.

Products liability is a legal term for the action whereby an injured party (plaintiff) seeks to recover damages for personal injury or property loss from a producer and/or seller when the plaintiff alleges that a defective product caused the injury or loss. This article provides information on the legal bases for products liability and definitions for two types of defects: manufacturing defects and design defects. It summarizes other possible defects in design as well as preventive measures.

This article briefly describes water and steam chemistry, which influence the effect of corrosion in boilers. The appropriate control measures to prevent corrosion in boilers are also presented. The article provides a discussion on the common causes of fluid-side corrosion such as flow-accelerated corrosion, oxygen pitting, chelant corrosion, caustic corrosion, acid corrosion, organic corrosion, phosphate corrosion, hydrogen damage, and corrosion-assisted cracking.

This article reviews the general characteristics of fretting wear in mechanical components with an emphasis on steel. It focuses on the effects of physical variables and the environment on fretting wear. The variables include the amplitude of slip, normal load, frequency of vibration, type of contact and vibration, impact fretting, surface finish, and residual stresses. The form, composition, and role of the debris are briefly discussed. The article also describes the measurement, mechanism, and prevention of fretting wear. It concludes with several examples of failures related to fretting wear.

X-ray diffraction (XRD) residual-stress analysis is an essential tool for failure analysis. This article focuses primarily on what the analyst should know about applying XRD residual-stress measurement techniques to failure analysis. Discussions are extended to the description of ways in which XRD can be applied to the characterization of residual stresses in a component or assembly and to the subsequent evaluation of corrective actions that alter the residual-stress state of a component for the purposes of preventing, minimizing, or eradicating the contribution of residual stress to premature failures. The article presents a practical approach to sample selection and specimen preparation, measurement location selection, and measurement depth selection; measurement validation is outlined as well. A number of case studies and examples are cited. The article also briefly summarizes the theory of XRD analysis and describes advances in equipment capability.

Fretting is a wear phenomenon that occurs between two mating surfaces; initially, it is adhesive in nature, and vibration or small-amplitude oscillation is an essential causative factor. Fretting generates wear debris, which oxidizes, leading to a corrosion-like morphology. This article focuses on fretting wear related to debris formation and ejection. It reviews the general characteristics of fretting wear, with an emphasis on steel. The review covers fretting wear in mechanical components, various parameters that affect fretting; quantification of wear induced by fretting; and the experimental results, map approach, measurement, mechanism, and prevention of fretting wear. This review is followed by several examples of failures related to fretting wear.

This article describes the microstructure, properties, and performance of carburized steels, and elucidates the microstructural gradients associated with carbon and hardness gradients. It provides information on case depth measurement, the factors affecting case depth, and the formation and causes of microcracks. The article discusses the effects of alloying elements on hardenability, the effects of excessive retained austenite and massive carbides on fatigue resistance, the effects of residual stresses and internal oxidation on fatigue performance of carburized steels. In addition, the causes of intergranular fracture at austenite grain boundaries and their prevention methods are explored. The article also describes the major mechanisms of bending fatigue crack initiation in carburized steels.

This article provides an overview of electromagnetic fields (EMFs) and discusses their direct and indirect effects on human health. It provides a detailed description of the exposure levels of EMFs in residential and work environments. The article examines the international and European standards and regulations regarding occupational exposure to EMFs encountered in industrial activities. It discusses the categories of work equipment or activities that may expose the worker above and under the orientation value. The article also describes the main principles underlying the protection system adopted for the frequency range of 50 Hz to 10 MHz.

This article briefly introduces the concepts of failure analysis and root cause analysis (RCA), and the role of failure analysis as a general engineering tool for enhancing product quality and failure prevention. It reviews four fundamental categories of physical root causes, namely, design deficiencies, material defects, manufacturing/installation defects, and service life anomalies, with examples. The article describes several common charting methods that may be useful in performing an RCA. It also discusses other failure analysis tools, including review of all sources of input and information, people interviews, laboratory investigations, stress analysis, and fracture mechanics analysis. The article concludes with information on the categories of failure and failure prevention.