Pressure Vessel Failures
Pressure vessels and pressure piping used in refineries, chemical processing plants, water treatment systems of boilers, low pressure storage tanks commonly used in process, pulp and paper and electric power plants operate over a broad range of pressures and temperatures and experience a variety of operating environments. Shell, head, attachments, and piping are some of the components that commonly fail.
Design errors, fabrication errors, corrosion, and improper maintenance are some of the causes of failures. Brittle fracture, stress corrosion cracking, fatigue, welding problems, erosion, creep, stress rupture, and hydrogen embrittlement are among some of the common failure modes found in pressure vessel components. Failure analysis can identify the root cause or causes that have contributed to your pressure vessel failure.
Corrosion is chemically induced damage to a material that results in deterioration of the material and its properties. This may result in failure of the component. Several factors should be considered during a failure analysis to determine the affect corrosion played in a failure. Examples are listed below:
When tensile stresses are applied to a hydrogen embrittled component it may fail prematurely. Hydrogen embrittlement failures are frequently unexpected and sometimes catastrophic. An externally applied load is not required as the tensile stresses may be due to residual stresses in the material. The threshold stresses to cause cracking are commonly below the yield stress of the material.
Hydrogen Embrittlement Failures
Tensile stresses, susceptible material, and the presence of hydrogen are necessary to cause hydrogen embrittlement. Residual stresses or externally applied loads resulting in stresses significantly below yield stresses can cause cracking. Thus, catastrophic failure can occur without significant deformation or obvious deterioration of the component.