Page 100 - Hydrocarbon Exploration and Production Second Edition

Safety and the Environment 87

Identify and describe
potential hazards

Evaluate likelihood and
consequences of hazard

Apply risk reduction
measures

Figure 5.3 General approach to quantitative risk analysis (QRA).

individuals to large groups, and their tasks may take days or months. The contractors
are therefore the group with the highest exposure to the operations, and often the
least familiar with the particular practices on an installation, since they move between
oil companies, and between installations. Special attention must be given to in-
corporating the contractors into the prevailing SMS by familiarising them with a new
location and work practices. This may be achieved through a safety induction-training
course.
Design procedures are developed with the intention of improving the safety of
equipment. Tools used in this step are hazard and operability studies and quantitative
risk analysis (QRA). The following scheme may be used (Figure 5.3).
In the first step, a screening process will be applied to separate the major
potential hazards, and a risk register or risk matrix is established; major hazards will be
addressed in more detail (see also Section 15.3.2, Chapter 15). QRA techniques are
used to evaluate the extent of the risk arising from hazards with the potential to
cause major accidents, based on the prediction of the likelihood and consequence of
the event. This assessment will be based on engineering judgement and statistics
of previous performance. Where necessary, risk reduction measures will be applied
until the level of risk is acceptable or ‘ALARP’. The acronym stands for as low as
reasonably practicable, and is a term often used in the context of safety-critical and
high-integrity systems. The ALARP principle is that the residual risk shall be as low
as reasonably practicable. For the risk to be ALARP it must be demonstrated that
the cost involved in reducing the risk further would be grossly disproportionate to
the benefit gained. In other words it would be possible to spend infinite time, effort
and money attempting to reduce a risk to zero.
‘Permit to Work’ procedures are written to ensure that activities are performed
in a systematic way. Before conducting work that involves confined space entry,
work on energy systems, ground disturbance in locations where buried hazards