Using engineering failure analysis, we examined how severe weld fatigue can lead to pressure vessel failure, and what can be done to prevent it. Working with one of the top pharmaceutical companies, we used fracture investigation along with extensive fatigue analysis to meet our targets within a strict deadline.
A large in-line pressure vessel suffered severe weld fractures as a result of structural fatigue. As an integral piece of equipment, it was crucial to the company that our weld failure and fatigue analysis be completed, and the equipment return to being operational, as efficiently as possible.
When working with pressure vessels, two approaches are needed. Firstly, weld fracture analysis is required to examine the cause of failure. Full metallurgical analysis of the welds and parent metal was conducted and examination of the manufacturing processes, especially the welding processes was examined.
Secondly, extensive stress analysis using Finite Element Analysis (FEA) covering thermal and pressure operational profiles was required. Stress analysis involving weld fatigue assessment was then conducted across all welds using BS 7608 standard in order to ascertain deficiencies in the design.
Successful failure analysis and investigation was achieved, and the root cause of failure determined. A collection of recommendations was advised regarding the weld design, welding method and materials used in the manufacture of the pressure vessel.