35
What Makes a Task Safety Critical?
as a result of insufficient knowledge about the task. A compensating measure is to
obtain the knowledge necessary to make informed decisions. This can easily become
a time-consuming task and turn into a case of overcompensation, unless one has the
right tools for the job.
As such, determining task criticality easily presents itself as an ungrateful piece
of work where spending enough time, but not too much, must carefully be balanced
to achieve the desired outcome. The aim of this chapter is therefore to expand the risk
management practitioners’ toolbox by providing an easy- to-use roadmap for determining task criticality.
MANAGEMENT OF OPERATIONAL BARRIER ELEMENTS
As explained above, identification and selection of safety critical tasks may be relevant
for work both as part of safety studies and risk management. The lessons learned,
described in this chapter, mainly stem from working with implementation of systems for managing operational barrier elements on various O&G installations on the
Norwegian Continental Shelf ( NCS), in both the design and the operational phase.
Operational barrier elements are part of the framework for barrier management
promoted by the Norwegian PSA both as part of their regulations and industry guidelines ( PSA, 2017). Other industry actors have also published guidance on barrier
management, some with a more practical orientation than what is currently communicated by the PSA. One such guideline is made available by the Norwegian
Shipowners’ Association ( NSA) ( Øie et al., 2014), from which most of the definitions
in this chapter are taken from.
An operational barrier element is a type of safety critical task and can be defined
as a task performed by an operator or team of operators, which realizes one or several barrier functions. Here “ realize” refers to performing the function when it is
required, which could be continuously or on demand, depending on the barrier’s performance requirements. The barrier function is in most cases realized through interactions with technical barrier elements. These are engineered systems, structures
or other design features which realize one or several barrier functions. The barrier
function itself is the role or purpose of the barrier in either preventing a hazard from
being released, controlling the accident escalation pathway, or mitigating undesired
consequences in case an event should occur ( Figure 3.1).
Examples of operational barrier elements are provided in Table 3.1. A separate
column titled “ Systems” has been added to aid the reader’s understanding by indicating which technology is involved.
On the NCS operational barrier elements fall under the same regulations as technical barrier e lements – §5 Barriers in the Management Regulations ( PSA, 2017). In
brief, §5 requires that barriers shall be implemented to manage risks emerging from
the major accident hazards ( MAHs) associated with the installation’s operations and
environment. Requirements for barrier performance ( e.g. functionality, integrity,
robustness) shall be defined based on the risk picture, and a plan for how to monitor
and maintain such performance shall be established and adhered to. The implementation of barrier functions and setting of performance standards ( i.e. strictness of
requirements) shall take into consideration the specific context of each area on the
What Makes a Task Safety Critical?
as a result of insufficient knowledge about the task. A compensating measure is to
obtain the knowledge necessary to make informed decisions. This can easily become
a time-consuming task and turn into a case of overcompensation, unless one has the
right tools for the job.
As such, determining task criticality easily presents itself as an ungrateful piece
of work where spending enough time, but not too much, must carefully be balanced
to achieve the desired outcome. The aim of this chapter is therefore to expand the risk
management practitioners’ toolbox by providing an easy- to-use roadmap for determining task criticality.
MANAGEMENT OF OPERATIONAL BARRIER ELEMENTS
As explained above, identification and selection of safety critical tasks may be relevant
for work both as part of safety studies and risk management. The lessons learned,
described in this chapter, mainly stem from working with implementation of systems for managing operational barrier elements on various O&G installations on the
Norwegian Continental Shelf ( NCS), in both the design and the operational phase.
Operational barrier elements are part of the framework for barrier management
promoted by the Norwegian PSA both as part of their regulations and industry guidelines ( PSA, 2017). Other industry actors have also published guidance on barrier
management, some with a more practical orientation than what is currently communicated by the PSA. One such guideline is made available by the Norwegian
Shipowners’ Association ( NSA) ( Øie et al., 2014), from which most of the definitions
in this chapter are taken from.
An operational barrier element is a type of safety critical task and can be defined
as a task performed by an operator or team of operators, which realizes one or several barrier functions. Here “ realize” refers to performing the function when it is
required, which could be continuously or on demand, depending on the barrier’s performance requirements. The barrier function is in most cases realized through interactions with technical barrier elements. These are engineered systems, structures
or other design features which realize one or several barrier functions. The barrier
function itself is the role or purpose of the barrier in either preventing a hazard from
being released, controlling the accident escalation pathway, or mitigating undesired
consequences in case an event should occur ( Figure 3.1).
Examples of operational barrier elements are provided in Table 3.1. A separate
column titled “ Systems” has been added to aid the reader’s understanding by indicating which technology is involved.
On the NCS operational barrier elements fall under the same regulations as technical barrier e lements – §5 Barriers in the Management Regulations ( PSA, 2017). In
brief, §5 requires that barriers shall be implemented to manage risks emerging from
the major accident hazards ( MAHs) associated with the installation’s operations and
environment. Requirements for barrier performance ( e.g. functionality, integrity,
robustness) shall be defined based on the risk picture, and a plan for how to monitor
and maintain such performance shall be established and adhered to. The implementation of barrier functions and setting of performance standards ( i.e. strictness of
requirements) shall take into consideration the specific context of each area on the