Operational frame work and safety studies for LNG operations

The design of port layouts and (offshore) terminals suitable for LNG-carriers has to meet exceptionally high safety standards. All responsible parties aim at the design of an inherently safe offloading system either on-shore or offshore.

In a port area a careful selection of the terminal location is combined with the definition of strict nautical procedures. Offshore all the focus is on the operational procedures and the interfacing connections.

The two-way approach of the design of a nautically safe LNG offloading system comprises:

The design of operations; this covers the layout of the infrastructure (onshore and offshore), the mooring system and the navigation procedures. Aspects that are addressed are:
• Terminal location or offshore facility, orientation and surrounding infrastructure,
• Mooring lines/fender configuration or hawser length and positioning system,
• Procedures on the approach, berthing, tug use, weather windows and emergency response.
Many of these aspects can be addresses through (full-mission) manoeuvring simulations using expert opinion.

The Quantitative Risk Assessment; such an assessment identifies hazards, quantifies the total risks and defines measures to reduce the risks. Typical hazards are collision, contact, foundering and grounding, fire and explosions. The most important associated risk is the loss of containment leading to life threatening gas clouds. Typical measures are slow speed tug assisted manoeuvring, single ship operation, standby tug, and proper terminal site selection.

In this paper we like to discuss two typical examples of a safety study combined with a design of operations. The design of the operation aims at obtaining a safety level that is equal or higher than predicted in the safety study. Especially when dealing with LNG this is an important goal. One study discussed in this paper is related to offshore operations (Case 1) and one for a typical port (Case 2).