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.

This article discusses the failure analysis of several steel transmission pipeline failures, describes the causes and characteristics of specific pipeline failure modes, and introduces pipeline failure prevention and integrity management practices and methodologies. In addition, it covers the use of transmission pipeline in North America, discusses the procedures in pipeline failure analysis investigation, and provides a brief background on the most commonly observed pipeline flaws and degradation mechanisms. A case study related to hydrogen cracking and a hard spot is also presented.

This article provides an overview of the classification of hydrogen damage. Some specific types of the damage are hydrogen embrittlement, hydrogen-induced blistering, cracking from precipitation of internal hydrogen, hydrogen attack, and cracking from hydride formation. The article focuses on the types of hydrogen embrittlement that occur in all the major commercial metal and alloy systems, including stainless steels, nickel-base alloys, aluminum and aluminum alloys, titanium and titanium alloys, copper and copper alloys, and transition and refractory metals. The specific types of hydrogen embrittlement discussed include internal reversible hydrogen embrittlement, hydrogen environment embrittlement, and hydrogen reaction embrittlement. The article describes preservice and early-service fractures of commodity-grade steel components suspected of hydrogen embrittlement. Some prevention strategies for design and manufacturing problem-induced hydrogen embrittlement are also reviewed.

Hydrogen damage is a form of environmentally assisted failure that results from the combined action of hydrogen and residual or applied tensile stress. This article classifies the various forms of hydrogen damage and summarizes the theories that seek to explain these types of degradation. It reviews hydrogen degradation in specific ferrous and nonferrous alloys, namely, iron-base alloys, nickel alloys, aluminum alloys, copper alloys, titanium alloys, zirconium alloys, and vanadium, niobium, tantalum, and their alloys. An outline of hydrogen damage in intermetallic compounds is also provided.

Hydrogen damage is a term used to designate a number of processes in metals by which the load-carrying capacity of the metal is reduced due to the presence of hydrogen. This article introduces the general forms of hydrogen damage and provides an overview of the different types of hydrogen damage in all the major commercial alloy systems. It covers the broader topic of hydrogen damage, which can be quite complex and technical in nature. The article focuses on failure analysis where hydrogen embrittlement of a steel component is suspected. It provides practical advice for the failure analysis practitioner or for someone who is contemplating procurement of a cost-effective failure analysis of commodity-grade components suspected of hydrogen embrittlement. Some prevention strategies for design and manufacturing problem-induced hydrogen embrittlement are also provided.

This article focuses on the analysis of materials and mechanical- (or biomechanical-) based medical device failures. It reviews the failure analysis practices, including evidence receipt, cleaning, nondestructive examination, destructive examination, exemplars analysis, and device redesign. The article examines the common failure modes, such as overload, fatigue, corrosion, hydrogen embrittlement, and fretting, of medical devices. The failure analysis of orthopedic implants, such as permanent prostheses and internal fixation devices, is described. The article reviews the failure mechanisms in some of the more common medical device materials, namely, stainless steels, titanium alloys, cobalt-base alloys, and nitinol. It presents case histories with examples for failure analysis.

Corrosion is classified into two categories: corrosion that is not influenced by any other process and corrosion that is influenced by another process such as the presence of stresses or erosion. This article discusses uniform corrosion, localized corrosion, metallurgically influenced corrosion, and microbiologically influenced corrosion, which fit under the classification of corrosion that is not influenced by any outside process. It also explains mechanically assisted degradation and environmentally induced cracking, which fit under the classification of corrosion that is influenced by an outside process.

This article discusses four types of defects in materials that have been fusion welded and that have been the focus of much attention because of the magnitude of their impact on product quality. These include hot cracks, heat-affected zone (HAZ) microfissures, cold cracks, and lamellar tearing. These defects, all of which manifest themselves as cracks, are characteristic of phenomena that occur at certain temperature intervals specific to a given alloy. The article presents selected alloy 625 compositions used in weldability study.

Visual examination, using the unaided eye or a low-power optical magnifier, is typically one of the first steps in a failure investigation. This article presents the guidelines for selecting samples for scanning electron microscope examination and optical metallography and for cleaning fracture surfaces. It discusses damage characterization of metals, covering various factors that influence the damage, namely stress, aggressive environment, temperature, and discontinuities.

Stress-corrosion cracking (SCC) is a phenomenon in which time-dependent crack growth occurs when the necessary electrochemical, mechanical, and metallurgical conditions exist. This article provides an overview of the environmental phenomenon, mechanisms, and controlling parameters of SCC. It describes the phenomenological and mechanistic aspects of the initiation and propagation of SCC. The article includes a phenomenological description of crack initiation and propagation that describes well-established experimental evidence and observations of stress corrosion. Discussions on mechanisms describe the physical process involved in crack initiation and propagation. The article also includes information on dissolution models and mechanical fracture models.

Overload failures refer to the ductile or brittle fracture of a material when stresses exceed the load-bearing capacity of a material. This article reviews some mechanistic aspects of ductile and brittle crack propagation, including a discussion on mixed-mode cracking, which may also occur when an overload failure is caused by a combination of ductile and brittle cracking mechanisms. It describes the general aspects of fracture modes and mechanisms. The article discusses some of the material, mechanical, and environmental factors that may be involved in determining the root cause of an overload failure. It also presents examples of thermally and environmentally induced embrittlement effects that can alter the overload fracture behavior of metals.

This article describes the types, mechanism, and typical test methods along with their configurations for the evaluation of hydrogen embrittlement, stress-corrosion cracking, and corrosion fatigue with an emphasis on fracture mechanics methodologies for metals. An overview on the environmentally assisted crack growth of polymers is also included. The article details the evaluation of nanoscale environmental effects and indentation-induced cohesive cracking. It also provides information on scanning probe microscopy.

This article is an atlas of fractographs that helps in understanding the causes and mechanisms of fracture of ASTM/ASME alloy steels and in identifying and interpreting the morphology of fracture surfaces. The fractographs illustrate the solidification cracking, creep failure, brittle fracture, fracture by overpressurization, inclusion effect, fatigue crack propagation, ductile fatigue striation, secondary cracking, intergranular fracture, and elevated-temperature fracture of alloy steels used in pressure vessels, steam boiler superheater tubes, and box-girder bridges.

Stress-corrosion cracking (SCC) is a cracking phenomenon that occurs in susceptible alloys, and is caused by the conjoint action of tensile stress and the presence of a specific corrosive environment. This article provides an overview of the anodic dissolution mechanisms and cathodic mechanisms for SCC. It discusses the materials, environmental, and mechanical factors that control hydrogen embrittlement and SCC behavior of different engineering materials with emphasis on carbon and low-alloy steels, high-strength steels, stainless steels, nickel-base alloys, aluminum alloys, and titanium alloys.

Fracture mechanics is a multidisciplinary engineering topic that has foundations in both mechanics and materials science. This article summarizes the microstructural aspect of fracture resistance in structural materials. It provides a discussion on basic fracture principles and schematically illustrates the mechanism of crack propagation. The article describes the fracture resistance of high-strength steels, aluminum alloys, titanium alloys, and composites such as brittle matrix-ductile phase composites and metal-matrix composites. It also lists the effects of microstructural variables on fracture toughness of steels, aluminum alloys, and titanium alloys.

This article briefly reviews the factors that influence the occurrence of intergranular (IG) fractures. Because the appearance of IG fractures is often very similar, the principal focus is placed on the various metallurgical or environmental factors that cause grain boundaries to become the preferred path of crack growth. The article describes in more detail some typical mechanisms that cause IG fracture. It discusses the causes and effects of IG brittle cracking, dimpled IG fracture, IG fatigue, hydrogen embrittlement, and IG stress-corrosion cracking. The article presents a case history on IG fracture of steam generator tubes, where a lowering of the operating temperature was proposed to reduce failures.