(182c) Identifying and Quantifying Major Hazard of Construction Lifting Activities

Lima Flow Station is one of gathering manned station of Pertamina Hulu Energy Offshore North West Java (PHEONWJ) which is located in Java Sea, Indonesia, which is consist of four bridge linked platforms and a bridge linked flare structure. Lima Flow Station was experienced subsidence for about 3 meters since it was built on 1973 to early 2013 resulting in significant reduction in the platform air gaps (distance between cellar deck bottom of steel and maximum wave height) which cause Lima Flow Station did not reliable for safe operation. The synchronous hydraulic jacking system was selected to raise the platform to 4 meters elevation and remedy the air gap for safe operation. Three platforms, flare tripods, and interconnecting bridge was raised while one platform was not raised as it was isolated and utilized as muster point and personnel transfer purpose only.

In order to execute deck raising by synchronous hydraulic jacking system, there were more than 500 tons of total load to be lifted, set up, and dismantled for more than 800 lifting activities, where the heaviest load was lift frame and Hydraulic Power Unit (HPU) for bridges having 65 tons of weight, and more than a half of the lifting activities were conducted during live platform. During lifting activities, there was possibility for lifted object to drop whether to topside facilities or to sea. Dropped object on topside facility might hit hydrocarbon equipment and personnel that might result in equipment damage, production loss, and fatality. Dropped object to sea might hit subsea hydrocarbon piping that might result in equipment damage and production loss. The lifted object themselves were parts of the project execution. Therefore any damage to lifted object whether when dropped to topside or sea might cause project delay which would contribute to production loss. Drop Object Risk Analysis (DORA) was conducted to quantify and assess the risk of the lifting activities for this project, develop recommendation for high risk lifting activities, and identify the contributors to keep the lifting activity safe.

Event Tree Analysis (ETA) was developed to identify how the lifting failure would lead to final event that was used as the basis for frequency analysis. The consequence analysis for drop object to topside facility involved the estimation of dropped object impact energy and hit object to receive such energy. The consequence analysis for drop object to sea utilized the well-known methodology published by DNV for risk assessment of subsea pipeline protection. The lifted object was assumed highly probable to damage when dropped to topside and sea. The study result showed that any main lifting activity for this project was in Medium or Low Risk which is included in As Low As Reasonably Practicable (ALARP) Region. The lifting activity was identified as major hazard, as the lifted object, such as welding machine on process platform, might drop to hydrocarbon equipment on topside facility. However, it possessed low level of frequency. As the severity level during lifting activity could not be reduced, project team focused on maintaining the frequency to keep the lifting activity safe by developing detail lifting plan, detail risk assessment, and thorough lifting tools and equipment inspection.

By implementing good project and risk management, Lima Flow Station Deck Raising has completed successfully and just start-up in October 2013 without any accident.