It includes everything
used within an asset’s chain-of-part needed to make an item of plant work
correctly—electrically, electronically, mechanically, structurally, and
software. The asset chain-of-part is all the equipment components needed to
make an asset operate as designed.
Implementing a
critical spares assessment
The critical spares assessment will
be affected by the operational strategy for risk which is in turn affected by
the contracts and penalties in force for loss of generation or production.
Other factors include maintenance systems, skills within the organisation and
dependency on external suppliers. The two extremes of risk strategy are conservative
operations or run until it drops. Most operational strategies will fall
somewhere in between.
Except for financial or IT institutions were the risk to
operation is so great that duplication of the entire systems is justified. Most
businesses or industries however do not have this luxury. Assessments must be made to determine the
parts of a system that are critical to operation, should a failure occur.
The critical parts assessment is to complete
the following review:
1. Facility
operation, and the demands and restrictions to operation. Ideally this should
have been considered during the procurement and build phases, when the known
operational data for various packages can be assessed before a commitment has
been made. Depending on the industry, this would look at information such as
fleet data, required availability/supply network and the option to have a
possible central storage of critical parts - the latter being more applicable
to power generation operators who can have a significant fleet of similar
units.
2. If the build is
complete and the facility operational, an assessment of the whole production
system using reliability centered maintenance or risk based assessment/inspection
processes should be completed. This should include the following.
a. Review history
of failed components for the individual plant and across the industry.
b. Review OEM
manuals.
c. Interviewing
the plant operational and maintenance personnel to capture and record existing
institutional knowledge.
d. Inspection of
the plant’s operational and maintenance supply chain. Do you have the
capability and skills to do this or is there a local network of suppliers who
could hold the critical spares and deliver them within the required time frames?
This requires the supply chain to be regularly audited to ensure availability
of the parts is maintained.
e. Perform a risk
assessment for the mechanical and electrical systems within the plant.
Determining the
critical electrical spares
Some typical questions that could be asked to
determine the likelihood of failure are:
- What is the age of the component?
- Are there damage processes and what is the
likelihood of …?
- Is rapid or unpredictable failure likely?
- How good are the current inspections?
- How good is the current maintenance?
- How well is the component currently operated?
Typical questions for the assessment of
consequences are:
- What would be the extent of damage to other
equipment?
- What is the part availability?
- What is the length of repair time?
- What is the safety hazard to personnel?
- What is the potential loss of production?
- What is the cost to repair or replace?
- Is there potential to cause damage to the
environment?
The critical part assessment is an integral
part of a facilities equipment integrity management system, and as such helps
the plant operators understand, develop and manage the following:
- Identifying equipment risk through reliability
based inspection.
- Identify all failure modes for each component.
- Detailed monitoring & inspection test
plans specific to each component.
- The most appropriate maintenance approach for
particular machines, systems, and areas.
- Suppliers, vendors, contractors, and internal
personal with regard to expectations in relation to reliability and
availability of critical items of plant.
To stop the risk of unexpected breakdowns each working part’s
reliability must be 100% for all its operating life, or else you need to remove
every opportunity for its failure during it service life. Otherwise you must
carry critical spare parts in your maintenance store.
For all critical spare parts, go with the strategy that
brings the highest probable business loss reduction for your company. No one
can know the future, but by basing your decision on the results from the risk
matrix you have arrived at the best chance your company can take to carry the
right spares to minimize its operating risks.
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