Fitness-for-service assessment of crack-like flaws for pressurized components

• Main Author: Lim, Ze Sin.
• Other Authors: Ong, Lin Seng
• Format: Final Year Project
• Language: English
• Published: 2009
• Subjects: DRNTU::Engineering::Mechanical engineering::Control engineering
• Online Access: http://hdl.handle.net/10356/15422
• Institution: Nanyang Technological University

Fitness-for-Service (FFS) is an assessment technique commonly employed within the petrochemical industry to determine the influence of a variety of flaws on the remaining life of the pressurized components or vessels. It is based upon the ASME and API design codes and standards for pressurized equipments during its design, fabrication, inspection and testing phases. This project aims to study the effect of crack-like flaws on pressurized components and to simplify the methodology of the assessment using Microsoft Excel spreadsheets. Two case studies are evaluated using Level 1 and Level 2 assessment procedures of the FFS assessment. They are both evaluated based on the criteria for Level 1 assessment; in this case, the first case study would meet the criteria and a Level 2 assessment would not be necessary whereas the second case study would require the use of a Level 2 assessment due to the inability to fulfill the criteria set for Level 1 assessment. Following the case studies, two separate Excel spreadsheet templates would be developed, catering to Level 1 and Level 2 assessments respectively. Excel spreadsheets allow automation in various tedious calculation processes and data verifications which in turn reduces the time spent on employing FFS assessment procedures. Currently, these two templates act as a skeletal framework for FFS assessment of crack-like flaws. Since no two flaws are identical, different flaw characterization methods are employed to classify them into different categories for ease of analysis. In this project, the spreadsheet templates are developed based on crack-like flaws parallel to the weld joint located on a longitudinal joint of a cylindrical vessel. To be able to comprehensively encompass all types of crack-like flaws, further work needs to be done in addition to the existing templates. For example, changes could be made to some of the assessment formulae in the spreadsheet for the respective flaw types, or developing a more automated process in terms of data verification and extraction for the spreadsheets.