Condition monitoring uses advanced technologies to determine the condition of equipment and predict failures in order to inform predictive maintenance. Techniques include motor current analysis, oil analysis, non-destructive testing, and integrated condition monitoring services which use non-invasive sensing to optimize maintenance. Risk-based inspection decides inspection intervals based on the risk of failure by considering probability and severity, while structural health monitoring monitors infrastructure over time using sensor data to detect damage in structures like bridges, oil rigs, and aircraft wings.

1. Condition Monitoring (CM)
Condition monitoring is the use of advanced
technologies to determine the condition of
equipment and predict its failure. This in turn
should inform predictive maintenance (PM) or
reliability-centred maintenance (RCM).

2. Techniques that can be used include:
• the Human Senses
– look, listen, smell, taste, feel etc.
• Motor Current Analysis
• Oil Analysis and Tribology
• Non-destructive testing (NDT)

3. 1. Integrated condition monitoring
service (ICMS)
proposes that "integrated condition
monitoring helps optimise maintenance by
judging the health of machinery using non-
invasive sensing technology".

4. The benefits of an ICMS approach
are:
• early detection of impending machinery failure to
help lower the risk of unscheduled downtime
• scheduling and utilisation of maintenance
resources is more efficient
• reductions in time spent in dry dock, if a pre-dry-
docking fault locating survey is performed
• reduced likelihood of ‘maintenance induced’
failures
• availability of global condition monitoring data.

5. 2. Risk-Based Inspection (RBI)
• a method for deciding which components
to inspect.
• instead of a fixed inspection interval, RBI
considers the risk of an item of plant,
or of a component, failing and decides the
inspection interval on that basis.

6. Risk assessment
• Consider the Probability (likelihood) and
the Severity (consequence) of failure
separately.
• classify them either as a range
or simply as low/medium/high
• the risk is the product of the two numbers
• a high number is a high risk
• endeavour to reduce the calculated risk

7. Risk assessment
Consequence of
failure
Low Medium High
High HIGH
RISK
Probability Medium
of Failure
Low LOW
RISK

8. 3. Structural Health Monitoring (SHM)
• a damage detection process used for
aerospace, civil and mechanical
engineering infrastructure which monitors
the system over time.
• typically, an array of sensors collects
dynamic response measurements either
continuously or at regular intervals.

9. So how might we monitor:
• an earth filled masonry arch bridge carrying a
road or railway
• cracking at joints in an offshore oil exploitation
rig jacket
• corrosion of a liquid storage tank
while full of hazardous chemicals
• barely visible impact damage
(dropped tools on CFRP aircraft wings)

10. The options include:
• mechanical/dead-weight loading with
measurement of deflections
• modes and frequencies of vibration
• embedded sensors
• non-destructive testing technologies