Framework of a Bow-Tie Based Quantitative Risk Assessment on an Offshore Oil and Gas Processing Unit

The study presents the proposal for a framework of a bow-tie based quantitative risk
assessment (QRA) on a system of an offshore oil and gas platform. Offshore operations
such as drilling or production are associated with a high level of risk because they
typically operate in a dynamic and tough environment, especially at the deep-water
region. The necessity of having an integrated methodology or a framework of risk
analysis will provide a supportive infrastructure for engineers in making decisions for
the purposes of risk mitigation and risk prevention during the new or operating
installations.
The subject of the study is to create a generic framework of quantitative risk
assessment (QRA) which is based on bow-tie method. The paper will start by
proposing on how the bow-tie based QRA will be done. Then, the paper will continue
by defining a system of an offshore oil and gas platform to be studied in the ‘System
Definition’ phase in which a case study using the proposed QRA will follow.
The framework will start by defining the system and a Fault Tree Analysis (FTA) will
be developed based on the simplified Process Flow Diagram (PFD). From the top event
of the Fault Tree Analysis, the top event will be used as the Initiating Event for the
development of Event Tree Analysis (ETA) which is proposed by the bow-tie method.
The consequences of the failure will be presented in the ETA.
In order to complete the risk equation, the probability of occurrence from the ETA will
be multiplied with its Impact or Consequences using Risk Matrix Analysis that is
proposed in ISO 17776 to rank the risks according to their risk levels.
The result of this QRA will be that when the highest risk of the systems has been
identified, it will be useful for the process or mechanical piping engineer to provide
improvement to the design or devise