Maintenance Systems

Covaris Pty Ltd
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Covaris White Paper - Maintenance Systems Formation ver 1-0.doc 1
Maintenance Systems Formation
Covaris Pty Ltd
PO Box 3456
Bankstown Square NSW 2200
Summary: The major topics dealt with in
this paper include identification of items to be
maintained under a preventative maintenance
schedule (PM) in a facility and the assessment of the
criticality of each of the nominated items of plant.
Based on the asset listing a preventative maintenance
schedule and inspection plan, covering simple
inspection, trade level overhaul tasks and condition
monitoring tasks may be established. Supporting the
schedule are requirements for sub-contractor
agreements and services, and statutory registers.
Where possible recommendations on critical spares
holdings and best practice maintenance policies
should be supplied. The whole process is managed
with a planning and scheduling approach, and
measured by KPIs for reporting maintenance
performance.
1.0 INTRODUCTION
The major steps in the maintenance systems
development include the assessment of the criticality
and performance of each of the nominated items of
plant. This will form the basis for maintenance and
process improvement analysis. Identification of the
plant equipment hierarchies involves demonstrating
parent child relationships for cost analysis and
performance analysis purposes. This is a strategic
aspect of the system since getting the plant dictionary
right is necessary for the remainder of the
maintenance system to work well.
Reliability analysis, identifying a risk-based priority
for a maintenance strategy, based on an
understanding of the failure modes sets priorities for
analysis of preventative maintenance (PM)
procedures based on a reliability block diagram /
production criticality overview. The preventative
maintenance schedule and inspection plan, covering
operator level inspection, trade level overhaul tasks is
developed using a reliability-centered maintenance
(RCM)-based strategy to schedule overhaul and
discard tasks, and condition monitoring tasks (again
using RCM methodology to assess failure modes to
be detected). An aspect of this work is to incorporate
in requirements from manufacturer recommendations,
Standards and statutory obligations
Work management policies should cover the
following:
o Planning and scheduling
o Work raising, management and acquittal
o Call outs
o Developing new procedures
2.0 PLANT DICTIONARY
The establishment of the plant dictionary has a
number of associated tasks:
1. Overall process for the facility – what is the
departmental breakdown
2. Operations requirements formulation –
standard interview process and
documentation
3. Past maintenance practices analysis
4. Criticality assessment – conducted in
conjunction with Process Mapping
Initial site visits to the facility will provide the
following information:
1. Full details of the current plant dictionary if
already loaded into a computer system
2. Appreciation of plant layout
3. Information on current plant maintenance
practices
4. Understanding of types and diversity of
assets
5. Understanding of criticality and reliability
of assets
Process mapping is a means by which a complex
machine or system of machines is broken down into a
logical hierarchy of maintainable items. A
maintainable item is defined as an item for which an
inspection is warranted to determine if it could failure
in the foreseeable future and that failure leads to an
undesirable outcome that will require an immediate
response. A sample process map is shown in Figure
1, identifying maintainable items within the flow of
the process stream.
Maintainable item criticality criteria are tabulated
from least consequence to worst. This is intended to
assist Planners and supervisors with set priorities for
work orders.
The logic for building a plant dictionary at the start
follows:
1. We need to conduct PM checks on items of
equipment
2. One of the PM work orders we need to
raise is the inspection of selected items of
plant
3. What do we look at in each item of plant
4. The plant item is made up of a number of
sub-systems, so we need another tier to the
second level to organise or sort the
maintainable items
5. What are the maintainable items that need
to be checked
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Covaris White Paper - Maintenance Systems Formation ver 1-0.doc 2
Jacket Water
Chiller
A1AE150
1A Mixer
A1AE140
1A Dough Tip Unit
A1AG205
Hopper
Sheeter
A1AG210
Gauge Roller 1
A1AG215
Gauge Roller 2
A1AG220
Gauge Roller 3
A1AG225
Transfer Web
Embosser Cutter
A1AG230
Scrap Lift
Conveyor
A1AH240
Inclined Conveyor
Transfer Conveyor
Reciprocating
Conveyor
Figure 1 Process map extract
An extract of a facility plant dictionary is shown in
Figure 2. This exhibits the hierarchical nature of the
plant dictionary.
Figure 2 Sample plant dictionary
An important note to consider here, which is a tip for
later stages of the work:
o A check is a quick visual inspection that is
intended to identify anything obviously
wrong
o An inspection should have a check sheet
accompanying it and is intended to provide
feedback that can be trended over time
o A PM task is one where someone may
check, inspect or conduct a time based
action which will prevent a failure
3.0 PROCEDURES WRITING
The relationship of maintenance strategies to
procedures and routines is identified in Figure 3. A
maintenance procedure must describe what has to be
done but not how to do it. It is important that the
competency of the trades staff is respected and taken
into account so that the procedures can be used as
simple check lists rather than cumbersome and
difficult to read documents, that may well be ignored
by the trades person.
What has to be done means that the following is
covered:
1. Items to be lubricated are listed and
specification of the lubricant is provided
2. When checks are to be made, the upper and
lower limits of acceptability are provided –
this is particularly important for electrical
checks
3. The difference between a check and an
inspection is that an inspection means that a
measurement has to be recorded – a check
means that the trades person views
something to ascertain whether it is OK or
not. Hence if an inspection is required
ensure that an inspection sheet is provided
as part of the procedure
4. If alignment or balancing or similar work is
required, then nominated points of
measurement have to be provided, possibly
requiring the trades person to write down
clearances or dial readings on an inspection
sheet
It is very important that Mechanical and Electrical
procedures are distinguished from each other. Other
categories of procedures can include Lubrication,
High Voltage and other specialised trades, eg
Plumbers, Civil, etc. We should not assume multiskilling
at a site, even if that makes sense, without
checking with the maintenance staff on their standard
practices.
It is common practice not to load into the Master
Maintenance Schedule and thereby into the work
management system routines with a periodicity more
frequent than monthly. Fortnightly routines need to
be treated on a case-by-case basis, but these are less
commonly used than weekly and monthly
frequencies. Daily and weekly routines are thereby
treated as Standard Operating Procedures (SOPs) and
are expected to be part of people’s standard job.
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Covaris White Paper - Maintenance Systems Formation ver 1-0.doc 3
There should be no need for a work order to be issued
for this work to be initiated. However we still write
the procedural description of the task list, and provide
this in a compiled set of SOPs that are handed over at
the same time as the procedure set loaded into the
work management system.
A procedure with its set of attendant operations is
shown below. Key information associated with the
procedure includes the resource type, expected
duration of the work, whether the machine is running
or not running, and the strategy grouping of the
procedure.
Figure 3 Design view of maintenance procedure
Procedures must be written to assist electronic loadup
into the work management system. Hence they
will need to be written in the first instance in a format
and media that facilitates this process. Additional or
supplementary information on procedures should
include:
1. List of materials that may be used in the
procedure – this is called the Bill of
Materials and should include the name of a
spare part, the stock code and the
Manufacturer. Possibly also the
Manufacturer’s item identifier code should
be listed as well.
2. Access requirements – this is particularly
important for isolations but may also
include what has to be done to access a
building (eg security requirements), or if
other equipment has to be removed or
isolated first
3. Documentation – drawing numbers,
software version numbers, where manuals
are located, etc
4. Consumeables – these are not items to be
included in the Bill of Materials but are
purchased material that may be used. This
would include all lubricants and any
disposable items.
4.0 PLANNING AND SCHEDULING
The overall view of a maintenance planning and
scheduling system is shown in Figure 4. This
identifies the key elements that are necessary for a
well-controlled maintenance system. Key
characteristics of a good system are set out in order of
priority from most important to very important:
1. Understanding of the plant processes –
what is important out there and when can
access be optimised
2. Use of the works management system –
functionality, flexibility, reporting, data
integrity
3. Project management – understand critical
path, set priorities, resource
planning/leveling (what can we do with the
people we have)
4. Communication – run planning meetings,
negotiate access to plant and services,
communicate backlog, risk and the strategy
to get through the work
MAINTENANCE
PLANS - PMs
STANDARD JOB
PROCEDURES
List of tasks
Job Safety Plan
Documentation
Bill of Materials
Inspections
Statutory checks
Condition monitoring
Appropriate for a type of equipment
SCHEDULE
CORRECTIVE
TASKS -
BACKLOG
List fo work orders for the week
WORK DONE
BREAKDOWNS,
URGENT CALLOUTS
% Schedule Work
Total Work Done
% PM
All Scheduled Work
REACTIVE
REACTIVE
PROACTIVE
Condition-Based Maintenance
Procedures
PROACTIVE
- triggered on condition
Figure 4 Planned and scheduled maintenance system
Note that breakdowns are not the province of the
Planner/Scheduler – they are the responsibility of the
team leaders or departmental trades people, who have
to organise a response. However the
Planner/Scheduler may get involved if these people
need access to site services, third parties etc.
Secondly, the Planner/Scheduler will support the
budget and procurement, and is expected to provide a
report to assist whoever is responsible for this, and is
expected to organise spares availability.
5.0 REPORTING
Routine reporting of key performance indicators
(KPIs) form the basis of the monitoring process for
performance-based maintenance. Maintenance
technical performance may be assessed by the
following measures:
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Covaris White Paper - Maintenance Systems Formation ver 1-0.doc 4
1. Frequency of work orders per week on a
rolling 12 month basis
2. Numbers of work orders sorted by Unit
basis
3. Pareto analysis of work orders on a Unit
basis
4. Downtime frequency per week sorted by
Unit on a rolling 12 month basis
5. Pareto analysis of equipment downtime
hours
6. Monthly downtime report – tabular format
of lost time incidents
Example plots are shown below:
0
10
20
30
40
50
60
70
Jul-00
Sep-00
Nov-00
Jan-01
Mar-01
May-01
Jul-01
Sep-01
Nov-01
Jan-02
Mar-02
May-02
N work orders
Raised
Closed
Figure 5 Sample work order frequency plot
0
5
10
15
20
25
30
N work orders
Nov-01
Dec-01
Jan-02
Feb-02
Mar-02
Apr-02
May-02
Jun-02
07-25
16R-34L
SSE
NE
Figure 6 Sample number of work orders
Backlog analysis is a Key Performance Indicator
(KPI) can show the risk outstanding with planned but
incomplete maintenance work. The backlog report is
a tool to distinguish between acceptable and high-risk
responsiveness to work requests. The report will also
show the specific tasks that are threats to the assets or
may need their criticality changed over time.
661 Backlog (05/02/2002)
0
5
10
15
20
25
30
1 10 100 1000 10000
Days
Figure 7 Sample backlog report
Each point on the plot is a work order, and the x-axis
refers to the days outstanding between when the task
was raised and the date of the analysis. The y-axis is
a measure of the risk of the work order, with 25
representing maximum possible exposure. The area to
the left side of the staggered line is the acceptable
performance area, where the time in backlog is
considered acceptable given the criticality of the task.
But the other side of the policy line identifies tasks
that are risks to the assets or need their criticality to
be reviewed over time.
6.0 CONCLUSION
The technical processes in establishing a maintenance
system include technical procedures improvement,
inspection management, reliability analysis, works
management system uptake and improved use,
including planning and scheduling of work, and
support for labour management. The end objective of
this work is to assure that the maintenance team has
the necessary systems and technical processes to
assist a consistent and well founded approach to
maintenance, covering use of the works management
system, a thorough maintenance plan and a mixed
resource base combining in-house and contract
labour. Tangible deliverables of this work include:
o Consistent and well structured plant
dictionaries within the works management
system, with appropriate criticalities of
plant identified
o Significant improvement in the technical
quality of procedures
o Wider use of inspections and reliability
analyses
o Planning and scheduling methods
improving the levels of planned work
o Management reporting and KPIs
The processes described in this paper and the
maintenance system design software are available as
services provided by Covaris Pty Ltd.