Stress corrosion cracking basics

BASICS OF CORROSION - STRESS CORROSION CRACKING (SCC) What is SCC? SCC is the conjoint action of stress and a corrosive environment which leads to the formation of a crack which would not have developed by the action of the stress or environment alone. Why is it a problem? Because, it can happen ‘unexpectedly’ and rapidly after a period of satisfactory service leading to catastrophic failure of structures or leaks in pipework. Where does it occur typically? Typical SCC failures are seen in pressure vessels, pipework, highly stressed components and in systems when an excursion from normal operating conditions or the environment occurs. Where do the stresses come from? The stresses that cause SCC are either produced as a result of the use of the component in service or residual stresses introduced during manufacturing. Where does the corrosive environment come from? The environment is either the permanent service environment i.e. sea water or a temporary one caused by operations such as cleaning of the system which can leave a residue, or if the stress is applied during the operation initiate cracking. How is this different from ‘normal’ corrosion? SCC is a corrosion mechanism that requires the pairing of a material with a very particular environment and the application of a tensile stress above a critical value. Corrosion can 1 [SCC/BM] occur in other environments without SCC. Examples of well-known material/environment pairs are: MATERIAL Brass Stainless…

Palavras-chave: análise de falha, falha por corrosão, ferramentas de manutenção, sistemática de análise. KOZLIK Jr., Antonio, A Systematic for Corrosion Failure Analysis of Metallic Mechanical Components, 2007, 126p. Dissertação (Mestrado em Engenharia) Programa de Pós-graduação em Engenharia Mecânica e de Materiais, Universidade Tecnológica Federal do Paraná, Curitiba, 2007. ABSTRACT A diversity of technical and economical features related to the life cycle of equipments,…

sistema nióbio/pentóxido de nióbio como sensor de detecção da permeação de hidrogênio. Palavras-chaves – eletroquímica do nióbio, fragilização por hidrogênio, sensor de hidrogênio, carregamento de hidrogênio. ABSTRACT One of the great problems found in oil refineries is the control of structural deterioration of steel in the units which compose the oil refining process. This deterioration is related to mechanisms which involve hydrogen embrittlement processes. Hydrogen produces…

propagação da fratura. III - Fratura Intergranular Ocorre a separação pura e simples ao longo dos contornos de grão (figura 2.16). Este mecanismo, totalmente frágil, é incentivado por grãos grosseiros, fragilidade de revenido, fragilidade da martensita revenida, filme de cementita em contornos de grão e ação de meios agressivos (ação de hidrogênio). Micromecanismos de fratura intergranular indicam um problema de material ou meio de trabalho. Mecânica da Fratura - 16 de 99 Figura 2.16…

committee of the American Society €or Testing and Materials and the American Welding Society. The joint committee also prepared the 1962revision. The first revision prepared exclusively by the AWS Filler Metal Committee was published in 1969. The current revision is the sixth revision and expansion as shown below: ASTM A371-53T AWS A5.9-53T Tentative Specifications for Corrosion-Resisting Chromium and Chromium-Nickel Steel Rods and Bare Electrodes AWS A5.9-62T ASTM…

transport of oil and gas in the offshore industry. During this process, corrosive gases, such as H2S and CO2, present in the composition of the transported fluid permeate through the polymer barrier of the pipe, creating an aggressive environment in the annular space. On this site, are found structures known as tensile armor of flexible pipe. The presence of high concentrations of H2S in the pre-salt fields, combined with the residual and service stresses, can enable the occurrence…

Diffusion Mechanisms 111 5.3 Steady-State Diffusion 112 5.4 Nonsteady-State Diffusion 114 5.5 Factors That Influence Diffusion 118 5.6 Other Diffusion Paths 125 Summary 125 Important Terms and Concepts 126 References 126 Questions and Problems 126 Design Problems 129 6. Mechanical Properties of Metals 131 Learning Objectives 132 6.1 Introduction 132 6.2 Concepts of Stress and Strain 133 ELASTIC DEFORMATION 137 6.3 Stress-Strain Behavior 137 6.4 Anelasticity 140 6.5…

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or third-party internet websites referred to in this publication, and does not guarantee that any content on such websites is, or will remain, accurate or appropriate. Contents Preface to Third Edition 1 page xiii Stress and Strain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 1.10 1.11 Stress Stress transformation Principal stresses Mohr’s circle equations Strain Small strains The strain tensor…