maintenance considerations in designjpak.jkr.gov.my/document/files/dokumen/slaid/l#1... · ‘vs...
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Design For Maintainability
• Design for Maintainability : guide to aid in achieving optimum
performance throughout lifespan of facility within minimum Life Cycle
Cost
• “Doing it right first time”: spearheading integration of designers,
constructors, FM, on outset of planning/design stage, through easy to
read tables summarizing (1) knowledge learnt from past mistakes, (2)
maintainability benchmarks
• Based on predictive/preventive strategies, tables define acceptable
standards in design, construction, operation practices
• Covers major facilities components for basements, wet areas, façades,
common areas, roofs, M&E & C&S services etc
(Maintainability of Building” database
(http://www. hpbc.bdg.nus.edu.sg)
Reality Today:
Performance Based Logistics & Supply Chain
Performance Warrantees
Autonomous Operation
More Emphasis on Contractor Performance
https://slideplayer.com/slide/4500678/
How Do we accommodate Change in
Philosophy ? Understand Requirement; Design to achieve them
Warranties:
Availability:
INHERIENT ?
ACHIEVED ?
OBSERVED ?
All the above
RELIABILITY?
MAINTAINABILITY?
DIAGNOSTICS?
TRAINING?
SPARES?
ALL THE ABOVE?
In Structured, Optimized Approach which Balances Acquisition Cost,
Capability, Performance & Support Cost i.e.
“A Structured Systems Engineering Process”
Basic Principles Of DfM
• Degree to which product allows safe, quick, easy replacement of
component parts
• Embodied in design of product. Lack of maintainability evident as
high maintenance costs, long down time, injuries etc
• Measure of maintainability: Time to Repair (TTR, ‘turn-around
time’)
• In public phone, target Time to Repair 15 minutes (on-site time) to
restore faulty payphone to full working order
• In large eqpt, maintenance times listed for different tasks on
individual parts of eqpt
Basic Principles Of DfM
4 Kinds of maintenance activity identified for any product:
• Preventative maintenance (PM), replace engine spark plugs
every 30,000 km, or change oil filter, requires replacement of
parts still working but expected to fail soon. Undertaken where
degradation of component endangers components elsewhere in
product. Old oil filter cause serious engine damage by starving oil
bearings, or allowing abrasive metal sludge into clean areas
• Remedial maintenance (repair), fit new vehicle starter motor
where existing burned out. Repair performed after product failed
• Anticipated life of component known, failure avoided by scheduled
replacement. Wholesale PM cheaper than piecemeal maintenance;
replace all fluorescent lights in office p.a. cheaper than replacing lights
individually, because labor used more efficiently
• Maintainability designed in, specify reliability x maintainability =
availability targets early in design cycle; early knowledge of anticipated
life of product & constituent parts & degree to which parts made
replaceable
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CLASSIC FUNDING BATTLE IS A PRIMARY
REASON FOR THIS DILEMA
Design For Maintainability (DfM)
Concepts
• Design defined as transformation of idea into process that meets
both designer’s requirements & end user’s needs
• Maintainability defined as degree (or ease) to which design can
be maintained (or repaired), both economically & efficiently
• Maintainability: characteristic of final design, whereas
maintenance = result of design
• Design for maintainability is designing plant to find optimum
balance between capital cost & ongoing maintenance cost
• Top 4 requirements:
ease of access,
standardization of eqpt both internally/between items,
skill levels to maintain eqpt &
redundancy of running eqpt, all have time to repair
component associated with them
Design For Maintainability
• Easier to access eqpt, shorter time required to maintain it
• Eqpt standardized, specialized maintenance skills not required,
reducing time to repair
• Focus on ‘time to repair’ (or mean down time), clear, plot of ‘MDT
‘vs ‘MTBM’ for various operational availability levels
• At 90% availability, plant engineer have 80 hours to complete all
corrective & preventative actions (not only failures) on plant, for
example
• In addition, this down time includes all delays, not only pure
repair time of eqpt
• At 95% target, available time reduces to 38 hours, while at 99%
target, 7 hours
Design For Maintainability
• Design team should aim to reduce MDT when piece of eqpt fails,
or requires PM. Some practical examples include:
• Provide lifting equipment access to all high maintenance
eqpt, e.g. pumps, pulleys
• Install permanent trolleys on all crawl beams to increase TTR
• Install standby pumps & dedicated pipelines (auto-
changeover, not affecting available maintenance hours/month)
• Make pumps accessible, under flooded plant conditions,
through walkways & access platforms
• Provide dedicated pipe routes with access
• Install split guards & split bearings on main conveyor pulleys
• Provide easy & clean access to all instrumentation
• Take cognizance of environmental implications of oil spills +
time to clean up.
Design For Maintainability
• Design parameter & not expensive if considered early in design
process
• Failure to take needs of maintenance team very expensive in
form of safety risks to personnel, retrofits to eqpt, operation
disruptions & cutting torch maintenance
• Design engineer review project goals & strategies with
operational team prior to design sign-off
• Design engineer invest time to compile design & installation
specifications & obtain sign-off from both operational teams &
contractor responsible for design & construction of services/eqpt
• During design process, utilize 3D design packages, review
maintenance access with key members of maintenance team
• Design improvements become apparent during construction
• Be flexible during construction & get maintenance team on site
early
Need for M - Prediction
• Prediction of expected nos of hours that system or
device in inoperative or “down state” while undergoing
maintenance of vital importance to user -adverse
effect from excessive downtime on mission success
• Once operational requirements fixed, technique
utilized to predict maintainability in quantitative terms
early during design phase
• Prediction updated continuously as design progresses
• Cheaper to improve design during construction
process, than disrupting value chain of running the
system
Useful Reference Materials
MIL-HDBK-472, Notice 1, Maintainability Prediction
MIL-HDBK-470a, Designing and Developing
Maintainable Products and Systems
In Conclusion, Ideal Design Criteria for Maintainability:
Maintenance is available on site with no waiting
Fault isolate is immediate and accurate Access is
direct
Necessary spare parts are on-hand
Maintenance is removed/replaced with no tools
required
No requirement to recalibrate, adjust, align or
otherwise verify
Definitions of Maintenance Action
• Element of maintenance event. One or more tasks necessary to
retain an item in or restore it to specified condition:
Fault Localization
Fault Isolation
Disassembly
Interchange
Reassembly
Alignment & Checkout
• Fault Localization – process of determining location of fault
• Fault Isolation – process of determining location of fault to the
extent necessary to effect repair
• Disassembly – opening of item & removal of parts or sub-
assemblies to make item to be replaced accessible for removal
• This does not include actual removal of item to be replaced
Definitions of Maintenance Action
• Interchange – Removing item to be replaced & installing
replacement item
• Reassembly – Assembly of items removed during disassembly
& closing reassembled items
• Alignment – Performing adjustments necessary to return an
item to specified operation
• Checkout – Tests or observations of item to determine its
condition or status
• Mean-Time-To-Repair (MTTR) – Basic measure of
maintainability. Sum of corrective maintenance times at any
specific level of repair, divided by total nos of failures within item
repaired at that level, during particular interval under stated
conditions
MTTR
• Mean-Time-To-Repair (MTTR)
Definitions of Maintenance
Strategies
• Availability – A measure of degree to which item is in
operable & committable state at start of a mission when
mission is called for unknown (random) time
• Maintenance – All actions necessary for retaining an item or
restoring it to a specified condition
• Preventive Maintenance – All actions performed in attempt to
retain an item in specified condition by providing systematic
inspection, detection, prevention of failures
• Corrective Maintenance – All actions performed as a result of
failure to restore an item to a specified condition
• Corrective maintenance can include any or all of the
following steps: Localization, Isolation, Disassembly,
Interchange, Reassembly, Alignment and Checkout
Predictive Maintenance
Examples:
• Chemical Analysis
• Vibration Analysis
• Infrared Scanning
• Ultrasound Scanning
• Bore pipes & Cameras
• Eddy Current Testing
Programmed Maintenance
• Goal of maintenance: prevent or reduce degradation or
deterioration of quality of service by each component over its
design service life
• Every component has finite service life
• Programmed Maintenance = PM + planned replacement
• Major Renovation
Human Factors Considerations
• Minimize skill requirements
• Minimize tools & test equipment
• Minimize adjustments and calibrations
• Allow for visual inspection if possible
• Put handles on heavy equipment
• Use bad-good or redline meters - avoid numerical
readouts
• Causes of Human Error
• Poor training and low skill levels
• Inadequate maintenance or operating procedures
• Inadequate supervision
• Poor working environment
• Improper or lack of motivati
Working Environment
• Noise pain at 130 db
• Illumination 50 foot-candles/lux equivalent for dials,
gauges, and meters
• Vibration exposure limits depends on frequency &
amplitude
• Ambient Air temperature (550 to 750 deg F.)
• Humidity
Key Factors when DfM
• Maintenance Policy
• Maintenance Staff - In-House; Outsourced
• Type of Equipment
• Maintenance Budget
• Rehabilitation Program
• Climate
IEEE 1219-1992
Maintenance phase 1: Problem Identification
a. Input
•The Maintenance Request (MR)
b. Process
•Assign change number
•Classify by type and severity etc.
•Accept or reject change
•Make preliminary cost estimate
•Prioritize
c. Control •Identify MR uniquely
•Enter MR into repository
d. Output •Validated MR
e. Selected
quality factors
•Clarity of the MR
•Correctness of the MR (e.g., type)
f. Selected
metrics
•Number of omissions in the MR
•Number of MR submissions to date
•Number of duplicate MR's
•Time expected to confirm the problem
a. Input
•Original project documentation
•Validated MR from the identification phase
b. Process
•Study feasibility of the MR
•Investigate impact of the MR
•Perform detailed analysis of the work required
•Refine the MR description
c. Control
•Conduct technical review
•Verify …
…test strategy appropriate
…documentation updated
•Identify safety and security issues
d. Output
•Feasibility report
•Detailed analysis report, including impact
•Updated requirements
•Preliminary modification list
•Implementation plan
•Test strategy
e. Selected
quality factors
•Comprehensibility of the analysis
f. Selected
metrics
•Number of requirements that must be changed
•Effort (required to analyze the MR)
•Elapsed time
IEEE 1219-1992
Maintenance phase 2: Problem Analysis
Maintainability
Users left out from design stage
• Early in design stage, designers discuss concept/idea for bldg w/representatives of owner/users
• Representatives not always ones finally occupy bldg, nor forward concept to future occupiers. Bldg users last group to be notified on what they can expect to have
Builder not notified of original concept or design intent
• Builder expected to price/construct based on drawings, w/ detailed instructions on how certain things constructed
• Very little briefing on original concept behind design, builders do not appreciate design intend or able to share design vision
Maintainability Strategy
• High system availability & reliability
• Align w/service partners; LCCM
• Sustainability of built environ (Green Mark)
• Design for Maintainability & operation
• Corrective, preventive, condition based, predictive maintenance
• CAFM & related ICT
• Take over audit/hand-back
EXAMPLE
• FP system poorly maintained higher average failure rate than same system maintained w/dedicated program, periodically
• Checklist & forms – MTNY based
• Predictable, specifiable,
measurable parameters
Spec design; Fault detection
Isolation, built-in test, auto test
eqpt, Comms for periodic
exercise/monitoring of FP eqpt
FMEA Criticality Analysis
M&E Reliability Stress Analysis
QA & Reliability, inclusion in
specs/contract for procurement of
critical FPS
Design For Sustainability Checklist
Checklist categories:
• General Maintenance Reduction
• Safety & Environmental System Design Features
• Design Standardization Features
• Design Features for Routine Maintenance
• Design Features for Troubleshooting
• Design Features for Repair/ Replacement
• Visual Inspections & Accessibility
• Design for Physical Accessibility
• M&E System Maintenance Design
• Personal Protective Equipment
• Storage Battery etc.
• DFM: product serviceable (easily repaired) & supportable (cost-effectively kept in or restored to usable condition)
• Durability (absence of failures)
• Reliability- how long eqpt down/available
Common Mistakes
• Planning & attention to smallest detail prevent mistakes that hinder
efficiency of maintenance facility
• Some of most common mistakes that create problems for vehicle
maintenance facility owners & managers
• Lighting – Important to choose lighting fixtures that offer full spectrum
of light. Lighting ramifications on efficiency, functionality, safety of
facility, on the general atmosphere of workplace
• High-pressure sodium lights may work well outdoors but aren't suited for
maintenance shop. Inside a building, light's orange-yellow cast creates
poor color rendition, making different colored wires look same & blood
indistinguishable from grease
• Overhead Clearance – Ductwork, plumbing, cranes installed too low
encroach on overhead space & interfere with required unobstructed
vertical clearance in repair bay, rendering cranes & lifts useless
Common Mistakes
• Door Size – Measure each vehicle's width/height – including mirrors &
vertical extensions
• 10’-wide ‘garage’ doors accommodate truck 8’ wide. Most trucks have
mirrors that protrude up to a foot on each side, which shrinks clearance
from 2’ to only few inches
• Building Finishes/Aesthetics – Bottom 4’ to 6’ of shop walls durable
(concrete or masonry) to withstand abuse in shop environment
• Make sure entire inside of building – walls/structure – painted to allow
proper maintenance to extend useful life of facility
• Designing facility's exterior to complement surrounding environment &
adding native landscaping help gain public approval of project
• Expandability – Building should not only handle shop's current work
load, should be adaptable & able to accommodate demands 20 years
from now
Common Mistakes
• Additional bays aren't built during initial construction, room left on site to
accommodate expansion. Also, load bearing walls avoided to maximize
flexibility for future modifications
• Public Involvement – Everyone interest in project to be informed
• Best-designed project won't get built if not approved bec’ elected official
or public doesn't understand importance of facility
• Appearance – Form follows function. Possible to make functional
building good-looking, but not possible to make a good-looking building
functional.
• Peer Review Sessions - During initial design phase, encourages shop,
fleet & fleet maintenance managers to hold peer review session; invite
other managers to day-long informal review session to ask them to
critique design. During session, peers can contribute great ideas &
validate design
Common Mistakes
• In project Aspen, one peer manager pointed out no
place to push the snow
• Install snow melt into pavement
• Designing maintenance facility complex process
• Asking right questions & planning carefully in advance
means maintenance managers will experience
smooth design & construction process that results in
safe, efficient, positive work environment that will last
whole life of facility
Sample – Maintenance Tasks
This information can be
found in MIL-HDBK-472 or
MIL-HDBK-470A. This
example shows remove &
replace times associated
with Standard Screws &
other types of fasteners
Above example of remove tasks for Elapsed Time Meter. The total
time is 4.03 minutes to perform tasks - Remove Time for this item
Sample – Replace Tasks
Above replace tasks for an Elapsed Time Meter. The total time is
5.15 minutes to perform tasks. Replace Time for this item. The
Interchange Time is sum of Remove Time & Replace Time for
item of interest
Sample – Prediction
Above example of simple Maintainability Prediction that includes
three replaceable items
What’s Next Software Wise?
• For more information, review other tutorials to see how ASENT
software help automate & manage Maintainability Analysis
The Challenge
• As consultant, frequently come across projects which require
software development skills able to give client comprehensive
service
The Solution
• By partnering with Ascent Software, extend range of services
offered by including software development in portfolio
• Software developers has significant vertical experience in
financial services, postal/logistics, aerospace, education,
transport, utilities & telecoms
Software Development
• Technical skills range from customization of Microsoft CRM &
Share-point, to projects requiring standard development skills, to
projects based on more advanced techniques such as A.I. and
Block-chain
• All stages in development cycle, option of determining level of
involvement in project; from simple referral up to being involved
in all the stages
• View [email protected]
Benefits
• Partner with premium development house & offer software
development
• Determine level of involvement in each project
• Tried & tested partnership model
8 Factors of Maintainability
1. Standardization
2. Modularization
3. Functional packaging
4. Interchangeability
5. Accessibility
6. Malfunction annunciation
7. Fault isolation
8. Identification
Others:
1. Planning
2. Df Reliability & Durability To minimize Service requirements
3. Overarching Principles - Simplification, Standardization & Mistake-Proofing
4. Df Diagnosibility
5. Process & Principles
6. DfS & Development Process
Summary
• Considerations of time, complexity, cost, functionality in a design
• Considering factors during design process provides meaningful
basis to balance needs of maintenance as we attempt to restore
system to service
• Cost of ownership function of main tenability & during design
process, ability to minimize number of bruised knuckles that
occur
DFS Analysis Of Company Items
• Exercise Objectives
• Analysis Methodology
• DFS Team Analysis Exercise
• Review of Team Findings
• Final Questions & Discussion
Conclusion
• Literature contains many references to criteria used in design to assess
maintainability
• Criteria are not independent & terminology used not consistent; very
detailed, quite unsuitable for concept design
• Literature collated to generate united set of criteria under 4 principal
headings: Personnel, Logistic Support, Operational Context, Design
• Criteria used to evaluate designs throughout design activity, more
particularly suitable for detailed design
• Concept design requires synthesis of diverse factors, some pertain to
maintainability, pressure on designers- create something that works at
acceptable cost
• Many detailed maintainability criteria just add to cognitive overload
• Comprehensive set of maintainability criteria analyzed to determine key
axioms
Conclusion
• Axioms: simplicity, parts/component features, operating
environment, parts identification & assembly/disassembly
• Influential design axioms to influence conceptual design of eqpt
• 3-D CAD systems principal design environments
• Virtual environments (VEs) using VE CAVES & haptic devices
attractive propositions
• When considering design that includes maintainability as principal
criterion, axioms above show potential for incorporation
• Whether VE has significant cost/benefit advantages compared to
desktop systems
• Further research develop axioms into embedded CAD & VE
software; investigate their effectiveness in VE systems
Key Considerations when Designing for
Pavement Maintainability
• Maintenance Policy
• Maintenance Staff
In-House
Outsourced
• Type of Equipment
• Maintenance Budget
• Rehabilitation Program
• Climate
Water, Water, Water
How Water Influences Design &
Maintenance
• Water Management Affects
Pavement Design
Shoulder Design
Subgrade Treatment
Horizontal alignment
Subdrain
Ditching
Landscaping
Pavement Design
• Pavement Design
Thickness
Subgrade Treatment
Type HMA vs PCC
Porous Pavement
Rehabilitation Strategy
Thank You !!