Stress and stability analysis of steel piping systems in the petroleum industry

Abstract

This study aims to reach a level of proficiency on the available technical theories to assess steel pressure piping systems and the identification of potential risks of failure. The research focuses mainly on piping systems in the petroleum industry. The importance of this study is based on the risk reduction of petroleum plant downtime and the harming of life as a result of piping failures. The apparent need for piping systems stress analysis was a result of the many failures that occurred at Indy Oil’s petroleum plant. The recent acquisition of the petroleum plant under the GUD Holdings group brought along minimum engineering experience with regards to piping systems. GUD’s inhouse engineering teams executed the many plant expansion and upgrade projects. A common industry perception is that piping systems are basic and do not require much attention. These misconceptions are a result of many piping failures in the industry. The failures that occurred called for a thorough investigation of all equipment setups and piping installations at Indy Oil. Specific failure identifications at the petroleum plant were done. The research and analysis of piping systems stress analysis were performed to aid in understanding the cause of these failures. Fluid dynamics, as a major contributor to stress and strain state in pipes, is the object of much attention. The dimensional specification and layout optimization of a piping system is highly dependent on the internal piping pressure. Studies, developments, and prediction analysis on the impact of sustained and thermal loads are reviewed to understand the numerical and analytical techniques available which enables the analysis of various piping systems. A risk- informed approach is applied that incorporates various design criteria, as well as, failure contributors in piping systems. At first, each component and failure mode is determined separately. Thereafter, the instances of simultaneous loading and increased risk of failure in piping systems have been determined. The available literature is used to source necessary data, as well as, compare the obtained results with those available in the literature. Government statutory requirements are used as a basis in the design process. Material specifications and engineering quality is controlled by these governing standards. The application of this study is done by the design and analysis of a piping system for Indy Oil’s Tank Farm. Piping systems failures as a result of improper design raised importance for a thorough stress analysis at the Petrochemical site. The calculations of stress-strain contributions are done using theoretical methods, as well as, computer software programs. The piping system is analysed on various conditions according to the process requirements of the Plant. Various load cases were developed to account for simultaneous loadings. The expected result of the system is for stress contributions to not exceed the maximum allowable stresses. CAESAR II software is selected as the most suitable for the analysis. The simulation is done on each pipe element and demonstrates a three-dimensional analysis. The results of the study were used to determine the failure modes of previously installed piping systems and to create a design guide for all future piping systems projects.