Search Results for operation-related failures

This chapter examines boiler tube failures attributed to operation-related causes. It discusses failures due to rapid start-ups, excessive load swing, excessive heat inputs, poor water chemistry control, and water-treatment methods.

This chapter reviews the knowledge of the field of gear tribology and is intended for both gear designers and gear operators. Gear tooth failure modes are discussed with emphasis on lubrication-related failures. The chapter is concerned with gear tooth failures that are influenced by friction, lubrication, and wear. Equations for calculating lubricant film thickness, which determines whether the gears operate in the boundary, elastohydrodynamic, or full-film lubrication range, are given. Also, given is an equation for Blok's flash temperature, which is used for predicting the risk of scuffing. In addition, recommendations for lubricant selection, viscosity, and method of application are discussed. The chapter discusses in greater detail the applications of oil lubricant. Finally, a case history demonstrates how the tribological principles discussed in the chapter can be applied practically to avoid gear failure.

The ability to accurately assess the remaining life of components is essential to the operation of plants and equipment, particularly those in service beyond their design life. This, in turn, requires a knowledge of material failure modes and a proficiency for predicting the near and long term effects of mechanical, chemical, and thermal stressors. This chapter presents a broad overview of the types of damage to which materials are exposed at high temperatures and the approaches used to estimate remaining service life. It explains how operating conditions in power plants and oil refineries can cause material-related problems such as embrittlement, creep, thermal fatigue, hot corrosion, and oxidation. It also discusses the factors and considerations involved in determining design life, defining failure criteria, and implementing remaining-life-assessment procedures.

This chapter examines the stress-corrosion cracking (SCC) failure of stainless steel pipe welds in boiling water reactor (BWR) service. It explains where most of the failures have occurred and provides relevant details about the materials of construction, fabrication techniques, environmental factors, and cracking characteristics. It includes a model that accounts for the primary factors involved in intergranular SCC, namely, tensile stresses above the yield stress of the base material, a sensitized microstructure, and reactor cooling water. The chapter also provides proven remedies and mitigation techniques corresponding to a wide range of issues related to stress, sensitization, and operating conditions.

This chapter provides an outline of the failure modes and mechanisms associated with most boiler tube failures in coal-fired power plants. Primary categories include stress rupture failures, water-side corrosion, fire-side corrosion, fire-side erosion, fatigue, operation failures, and insufficient quality control.

Root cause of failure in automotive electronics cannot be explained by the failure signatures of failed devices. Deeper investigations in these cases reveals that a superimposition of impact factors, which can never be represented by usual qualification testing, caused the failure. This article highlights some of the most frequent early life failure types in automotive applications. It describes some of the critical things to be considered while handling packages and printed circuit board layout. The article also provides information on failure anamnesis that shows how to use history, failure signatures, environmental conditions, regional failure occurrences, user profile issues, and more in the failure analysis process to improve root cause findings.

Quantifying a fault-tree analysis is a useful tool for assessing the most likely causes of a system failure. This chapter addresses fault-tree analysis event probabilities and ranking of failure causes based on these probabilities. Failure rates, failure-rate sources, probability determinations, mean times between failure, and related topics are also discussed. The discussion covers the practices observed in fault-tree analysis quantification and processes involved in calculating the probability of the top undesired event.

This chapter targets areas that determine if a change occurred and if the change induced the failure: change or what's different analysis. It describes the different sources of changes that induce process deficiencies: design, process, test and inspection, environmental, supplier lot, aging, and supplier changes. The chapter presents an example of a cluster bomb failure to explain how the failure analysis team found and corrected the failure cause.

This chapter provides a brief review of industry’s battle with fatigue and fracture and what has been learned about the underlying failure mechanisms and their effect on product lifetime and service. It recounts some of the tragic events that led to the discovery of fatigue and brittle fracture and explains how they reshaped design philosophies, procedures, and tools. It also discusses the influence of material and manufacturing defects, operating conditions, stress concentration and intensity, temperature and pressure, and cyclic loading, all of which play a role in the onset of fatigue cracking and thus should be considered when predicting useful product life.

In embedded systems, the separation between system level, board level, and individual component level failure analysis is slowly disappearing. In order to localize the initial defect area, prepare the sample for root cause analysis, and image the exact root cause, the overall functionality has to be maintained during the process. This leads to the requirement of adding additional techniques that help isolate and image defects that are buried deeply within the board structure. This article demonstrates an approach of advanced board level failure analysis by using several non-destructive localization techniques. The techniques considered for advanced fault isolation are magnetic current imaging for shorts and opens; infrared thermography for electrical shorts; time-domain-reflectometry for shorts and opens; scanning acoustic microscopy; and 2D/3D X-Ray microscopy. The individual methods and their operational principles are introduced along with case studies that will show the value of using them on board level defect analysis.

Designs and materials continue to become more complex, with novel technologies developed to create them, and novel instruments invented to analyze them. Engineers at all stages of the design and manufacturing process should appreciate the reasons why formal failure analysis is performed. This chapter describes why failure analysis is conducted and outlines the responsibilities of the failure analyst.

The testing of plastics includes a wide variety of chemical, thermal, and mechanical tests. This chapter reviews the tensile testing of plastics, which has been standardized in ASTM D 638, "Standard Test Method for Tensile Properties of Plastics," and other comparable standards. It describes the fundamental factors that affect data from tensile tests, examines the stipulations in standardized tensile testing, and discusses the utilization of data from tensile tests.

This chapter reviews failure aspects of structural ferrous powder metallurgy (PM) parts, which form the bulk of the PM industry. The focus is on conventional PM technology of parts in the density range of 6 to 7.2 g/cc. The chapter briefly introduces the processing steps that are essential to understanding failure analysis of PM parts. This is followed by a section on case hardening of PM parts. The methods used for analyzing the failures are then discussed. Some case studies are given that illustrate different failures and the methods of prevention of these failures.

Over the revolutionary era of semiconductor technology, Computer-Aided Design Navigation (CADNav) tools have played an increasingly critical role in silicon debug and failure analysis (FA) in efforts to improve manufacturing yield while reducing time-to-market for integrated circuit (IC) products. This article encompasses the key principles of CADNav for various aspects of semiconductor FA and its importance for improved yield and profitability. An overview of the required input data and formats are described for both IC and package devices, along with key considerations and best practices recommended for fast fault localization, accurate root cause analysis, FA equipment utilization, efficient cross-team collaboration, and database management. Challenges with an FA lab ecosystem are addressed by providing an integrated database and software platform that enable design layout and schematic analysis in the FA lab for quick and accurate navigation and cross-tool collaboration.

This chapter provides an overview of environmental factors when studying a gear failure. Environmental factors discussed are lubrication, temperature, and mechanical stability.

This chapter focuses on the failure aspects of tool steels. The discussion covers the classification, chemical composition, main characteristics, and several failures of tool steels and their relation to heat treatment. The tool steels covered are hot work, cold work, plastic mold, and high-speed tool steels.

Electronics spans a number of devices, their configurations, and properties. A challenge is to identify those electronic subjects essential for failure analysis. This article reviews the normal operation and terminal characteristics of MOSFET. It describes the electronic behavior of bridges, opens, and parametric delay defects, which is essential for understanding the symptoms of a failing IC. These electronic principles are then applied to a CMOS failure analysis technique using a power supply signature analysis.

This chapter describes the nine steps of a failure investigation. The steps add detail to the problem-solving process introduced in Chapter 3. The first five steps are (1) understanding and negotiating the investigation goals, (2) obtaining an understanding of the failure, (3) objectively and clearly identifying all possible root causes, (4) evaluating the likelihood of each root cause, and (5) converging on the most likely root cause(s). Many failure investigations stop at this point, but significant value is provided in the next four steps, which are (6) identifying all possible corrective actions, (7) evaluating each corrective action, (8) selecting the optimal corrective action(s), and (9) evaluating the effectiveness of each corrective action. Each step is discussed in detail with examples along with information on the procedures to be followed and resources needed for the investigation.

Fracture mechanics is a well-developed quantitative approach to the study of failures. This chapter discusses fracture toughness and fracture mechanics, linear-elastic fracture mechanics, and modes of loading. The discussion also covers plane strain and stress and crack growth kinetics. The chapter presents a case history that illustrates the use of fracture mechanics in failure analysis. An appendix provides a more detailed discussion of fracture mechanics concepts.

This chapter provides a detailed discussion on five occasions that require written accounts. They are field report, transmittal report with failed unit, laboratory notes of the analyst, failure analysis report, and letter of transmittal of the report to the customer.