Risk assessment

Steps of a risk assessment

During development of a bunkering facility, a risk assessment should be carried out to assess the risks to staff and the environment. Such an assessment will generally comprise the following steps:

  • Hazard identification: What can potentially go wrong?
  • Assessment of potential impacts by means of an impact assessment.
  • Assessment of probabilities: How often is an incident likely to occur?
  • Assessment of overall risk: Are the risks acceptable, or should risk-reducing measures be taken?

As part of the risk assessment a so-called criticality matrix can be used. In this kind of matrix, shown below, failures can be depicted in relation to their severity and probability. A higher number means greater severity or likelihood of occurrence. Failures in the green region have a negligible risk, while those in the yellow region require risk reduction measures. Failures with a high probability of occurrence in combination with a high severity of impact are not acceptable and should be avoided at all times.

                                                                              Criticality matrix

Safety distances

Based on the risk assessment, safety distances must be determined and established around the bunkering facility. Within this safety distance the likelihood of flammable mixtures as a result of any LNG release exceeds a certain limit (the minimum limit is determined by government authorities, while port authorities are free to enforce stricter limits) needs to be determined. Within this perimeter only trained staff are allowed and only essential activities are allowed during bunkering. Safety distances can be determined for each individual step of the LNG supply chain.

Risk distances

Besides safety distances, the risk assessment also helps determine risk distances. Risk distances are used to determine the size of the area around the bunkering location (facility + ship), where other activities like ship traffic are monitored (and if necessary controlled) to prevent harmful impacts. In this way possible ignition sources can be reduced and collisions avoided.

The exact safety and risk distances will depend, on the one hand, on port specifics (port layout, type and scale of other activities in the port and in the surrounding area, i.e. housing, industry, etc.) and, on the other, on the type of bunkering operation and other LNG-handling steps in the supply chain: Truck-to-ship bunkering will require other safety and risk distances than ship-to-ship bunkering.

Focus of LNG working group on risk perimeters

The WPCI LNG Fuelled Vessels Working Group focuses on the risk perimeters of LNG bunker operations and aims to create an overview of the risk perimeters currently implemented and enforced. In addition, the working group in general aims to contribute to the harmonisation of safety procedures between ports, where possible, while allowing for their varying characteristics (port activities, geographical location, traffic density, etc.).

Further reading

 

Safety

The cryogenic characteristics of LNG may pose a risk to humans and materials if not handled carefully. If ignited, a gas cloud resulting from LNG release may lead to several types of fire or an explosion at flammable methane concentrations.