Assessment of Corrosion in Offshore Structures through Inspection Reports and Experiments

• Main Author: Ong, Shiou Ting
• Format: Final Year Project
• Language: English
• Published: Universiti Teknologi Petronas 2010
• Subjects: TA Engineering (General). Civil engineering (General)
• Online Access: http://utpedia.utp.edu.my/1035/1/0001.pdf; http://utpedia.utp.edu.my/1035/
• Institution: Universiti Teknologi Petronas

Corrosion in Marine and Offshore Structures such as Jacket platforms and jetty piles is one of the issues to be considered during the design and maintenance. The current corrosion allowance in the splash zone for structural element is l2mm (PTS 20.073). Currently, no studies had been done on determining the appropriate corrosion allowance for offshore steel structures in Malaysia. This issue is crucial because many of the around 200 offshore structures in Malaysia are reaching their design life and a lower corrosion allowance would mean that they can be continued to be used without strengthening the structures. There are five zones at the seawater environment which include subsoil, continuously submerged, tidal, splash zone above high tidal and atmospheric zone. The rate of corrosion varies in different zones. The goal of this project is to define corrosion allowance and evaluate the effectiveness of the cathodic protection and anodes on offshore structural members from PETRONAS inspection reports. This goal is achieved in three stages : collection and analyse the PCSB Underwater Inspection Maintenance data from various platforms, conduct an experiment which involves fabricating of samples of different types of tubular members and immersing the same in different seawater zones at BOUSTEAD shipyard at Lumut. The samples will be inspected periodically and measurements will be taken to determine the nature and rate of corrosion. The results will be compared with the recommended values in the current code. The implementation of the correct corrosion allowance would benefit PETRONAS in terms of cost reduction and excellent structure integrity in all circumstances. Case study on all the reports for the platform in Sabah showed that data was not available from earlier inspection which could have been missed during platform handover.