Fitness-for-service : assessment of local metal loss
Ng, Davis Quen Fai.
Date of Issue2009
School of Mechanical and Aerospace Engineering
The Fitness-For Service (FFS) procedure is practiced in the industries that are involved in pressurized components. These set of assessment procedures are applied to provide results that the plant operator can make use of to carefully decide the operating safety and usage of the equipment to minimize breakdowns and productivity of the equipment. This report reviews the Fitness-For-Service criteria and assessment procedures for local metal loss in the pressurized components. The procedures and evaluation techniques carried out on the equipments are based on the assessment procedures in the American Petroleum Institute (API) Recommended Practice 579. In performing the FFS assessment, it will help the operator to maintain the process plant equipments’ reliability and the operational safety of the operator and environment. The FFS assessment procedures consist of three interrelated levels of assessment. These procedures are usually performed in a sequential manner from level 1 to level 3 assessments. The increasing assessment level differs in certain fields related to the amount of data required for the individual assessment, skill level of the operator assessing the equipment, accuracy of the operating equipment and the complexity of the assessment being performed. This project aims to understand the FFS assessment procedures for localized metal loss and to create a formulated excel spreadsheet based on the API RP 579. The excel spreadsheet is created to ease the plant engineer and operator in referring to the standards when performing the required FFS level assessment. The FFS assessment procedures were closely studied and the data required for the different assessment levels have been incorporated into the excel spreadsheet. The required data for the FFS assessment for localized metal loss were tabulated and generated in a step-by-step formulated excel spreadsheet. Upon inputting the required equipment dimensions and data into the spreadsheet, the user will just need to follow the procedures stated in the excel spreadsheet to conclude the acceptance of the equipment. Furthermore, examples are presented to illustrate the approach in the assessment of the pressurized equipment with localized corrosion and a groove-like flaw. In each example, the step by step procedures and assessment criteria are pointed out. In using the formulated excel spreadsheet, instead of referring to the standard frequently and manually tabulating and recording the results after each calculation, the plant engineer will be able to assess the equipments by following the assessment steps in the spreadsheet and producing the assessment results in a short time.
Final Year Project (FYP)
Nanyang Technological University