Risk-based inspection integrates asset
integrity and classification requirements
For some two decades, risk-based inspection (RBI) has been embraced by the oil and gas industry to enhance asset integrity. RBI is a risk-based approach to prioritizing and planning the inspection of assets, equipment, and components. Inspections are centered on engineering analysis and the potential for failure.
The approach uses past operating conditions and inspection data to
make strategic future predictions, capturing a ‘risk snapshot’ in time.
This involves the determination of a probability of failure combined
with the consequence of failure. At some point in the future, when a risk
tolerance is expected to be exceeded, an inspection is recommended
to better quantify the state of the component. The inspection itself
does not reduce the risk, but it mitigates the uncertainty associated
with the current degradation state. This enables operators to better
quantify the current damage present in the component and helps engineers make more accurate projections on the asset’s remaining life.
To carry out a successful RBI program, a series of tasks are un-
dertaken alongside a system breakdown. An RBI plan will identify
the following essential elements:
• Failure modes and degradation mechanisms
• Inspection scope, including identification of critical locations
• Optimization of inspection intervals
• Inspection processes and techniques.
While the oil and gas industry has employed integrity management
and, more often than not, risk-based methodologies and technology
to meet safety requirements and serve its operational goals, there is
one exception: floating offshore installations. This is an important
area where RBI can really help. With ever-tougher market conditions,
ever y difference counts. Greater efficiencies are needed across entire
operations and assets, including those with a hull.
Integrating RBI into class
The oil and gas industry has matured differently compared with
the marine industry, but the two converge when it comes to floating
offshore installations (FOI), such as FPSO assets, FPUs, and FLNG
units. FOIs are usually designed and built to marine classification
society rules, setting out how operators should maintain the hull and
incorporate five yearly prescriptive survey regimes, in addition to the
annual, intermediate, special surveys, and dry-dockings. There is no
provision for an RBI scheme within the relevant national administra-
tion or IMO conventions and codes. Verification ensures that the
relevant performance standards are being met; this is often carried
out by the class society, particularly in the UK. Integrity management
is run separately, focusing on maintaining safe FOI production. What
if these two aspects were brought together for FOI hull structures,
systems, and associated components?
Introducing a single sur vey and inspection program that combines
asset integrity and classification requirements offers some distinct
benefits. For a start, inspection activities would only need to be con-
ducted once, based on engineering needs. Inspection and maintenance
regimes would be optimized in line with operations. Costs would be
reduced by eliminating unnecessar y integrity management activities.
Mapping an RBI survey program to suit a facility and an asset integrity
program – while also providing justification for the assignment of class
– has the potential to save significantly when preparing for surveys
requiring cargo and ballast tank entry. Such preparation costs far
exceed class sur vey fees, before considering the lost production time;
considerable effort and expense are required before a surveyor even
sets foot on the asset. Ensuring all the inspection tasks are coordinated
under one plan, and carried out on the basis of engineering needs, is
just the sort of efficiency the industry requires.
Safety is also enhanced with a single scheme. Engineering analy-
sis now informs where inspections are concentrated. Operators can
look at their assets consciously based on what needs to be done for
their assets to remain safe and productive. The risk to personnel is
significantly reduced too; people are not being placed in potentially
hazardous spaces unnecessarily.
Besides efficiencies and safety improvements, a combined approach
can also take into account factors before the FOI went into service.
This is a welcome development. Many operators design and build to
a standard higher than the class minimum requirement, such as ap-
plying better coatings or enhancing the structural detail. The thinking
is that exceeding certain standards will allow for higher reliability
and a longer time on station. However, operators do not receive any
credit from a class perspective for building to a higher standard. Class
survey requirements do not recognize different standards; survey
cycles and the extent of surveys are fixed.
This single approach is not a new idea, but it has become ever more
pressing. In 2016, Lloyd’s Register found 70% of clients in a survey
answered ‘yes’ when asked if there was a need for RBI to be applied
to hull structures. (The survey was conducted at a business breakfast
panel involving 50 industry delegates.) In fact, for a decade or so the
industry has debated such an approach, but talk has failed to gain
momentum. There have been a couple of hurdles. First, FOIs are ex-
tremely complicated structures. It is a challenge to arrive at a base line
for such assets; there could be hundreds of thousands of inspectable
A single approach to integrity management and class can be applied at
any asset stage. (All images courtesy Lloyd’s Register)