RISK BASED INSPECTION PLANNING FOR FIXED PLATFORM
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 perf...
Saved in:
| Main Author: | |
|---|---|
| Format: | Final Project |
| Language: | Indonesia |
| Subjects: | |
| Online Access: | https://digilib.itb.ac.id/gdl/view/35380 |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| Institution: | Institut Teknologi Bandung |
| Language: | Indonesia |
| Summary: | 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. |
|---|