RISK BASED INSPECTION PLANNING FOR FIXED PLATFORM

• Main Author: Ceismi Fannisa, Nadita
• Format: Final Project
• Language: Indonesia
• Subjects: Teknik (Rekayasa, enjinering dan kegiatan berkaitan)
• Online Access: https://digilib.itb.ac.id/gdl/view/35380
• Institution: Institut Teknologi Bandung

The ability of offshore structures to fulfill their intended functions can be compromised because of deterioration. Routine platform inspections shall be conducted to detect, properly measure and record any platform defects, deterioration or anomalies that affect the structural integrity and performance. Risk Based Inspection (RBI) is a risk assessment and management process that is focused on failure modes initiated by material deterioration, and controlled primarily through structure inspection. Risk in RBI is considered to be the combination of consequence of failure (CoF) and probability of failure (PoF). Semi-quantitative approach was used for evaluating the risk. This final project presents a case study of an eight-legged jacket platform that was installed in 1992 and has been operating for the past 20 years to be extended its service life into another 20 years. The purpose of this final project is to indicate the inspection interval for a critical member connection due to wave cyclic loading that leads to fatigue failure mode. Spectral fatigue analysis performed by using SACS software (in accordance with Code API) to specify which member connection has the lowest fatigue life (the design fatigue life is forty years including Safety Factor of 2). The result showed that member connection 110-125 and 10R-126 with fatigue life of 25.1749 and 26.3847 years will then be inspected. With SN-fatigue approach, to estimate the probability of member connection failure, reliability calculation was performed by Matlab software and solved using Monte Carlo simulation technique. Member connection 110-125 and 10R-126 was assessed and has the annual PoF of 0.01514/year and 0.01519/year. A qualitative approach used for evaluating contamination, safety, environmental, production and economic consequences of the member connection 110-125 and 10R-126. Given the results, consequence level (CoF) was considered high. By using Risk Matrix from Code Norsok Standard Z-008, level of risk for member connection 110-125 and 10R-126 were obtained to be Medium Risk, thus the interval inspection according Draft API RP 2SIM ranges from 6 years to 10 years. As a conclusion from the analysis, the platform must be inspected as soon as possible to detect crack with inspection method using Radiography Testing or Remotely Operated Vehicle (ROV), then the inspection interval is determined to be every 6 years.