Machine Criticality 101 Don Silcock
GE Energy
Why is this topic important?
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Scenario Your customer wants to expand
the System 1® on his critical machines to manage other assets in his plant. How would you go about deciding
which of our solutions to advocate?
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Why is this important?
Technology / Solution
Maintenance Strategy
Improved Business Performance
Customer Business Objectives
Business objectives drive the maintenance strategy, which in turn drives the technologies and solutions applied.
Maintenance strategy definition and development is a critical success factor in the
customer’s value chain.
Terminology
6
Terminology
The four main maintenance strategies are:
• Reactive Maintenance (RM)
• Preventive Maintenance (PM)
• Predictive Maintenance (PdM)
• Proactive Centered Maintenance (PCM)
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Terminology
Reactive maintenance (RM):
• Maintenance performed after a failure or after an obvious, unforeseen threat of immediate failure.
•In reactive maintenance, machines are operated in a run-to-failure (RTF) mode
• Daily maintenance activities are driven by unforeseen problems from assets breaking down without detection of the impending failure.
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Terminology
Preventive Maintenance (PM):
• Maintenance tasks conducted at regular, scheduled intervals based on average statistical/anticipated lifetime to avoid failure
• Includes inspection, service and/or replacement
• Intervals may be calendar or operating time.
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Terminology
Predictive Maintenance (PdM):
• Maintenance based on the actual asset condition (objective evidence of need)
• Assessment data obtained from in-situ, non-invasive tests and operating & condition measurements
• Also referred to as Condition Based Maintenance (CBM).
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Terminology
Proactive-Centered Maintenance (PCM):
• A program of continuous maintenance optimization
• Based on feedback from Root Cause Failure Analysis (RCFA) repairs, quantitative PM’s, PdM routines, CM systems and operations.
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Terminology – other acronyms…
• MTBE: Mean Time Between Events
• MTBF: Mean Time Between Failure
• MTBR: Mean Time Between Repairs
• MTTR: Mean Time To Repair
• MRO: Maintenance, Repair, Overhaul
• OEM: Original Equipment Manufacturer
• O&M: Operating and Maintenance
• ERP: Enterprise Resource Planning
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Terminology
Condition Monitoring (CM):
• The process of recording measurements that define condition without disrupting operation
• Examples are vibration, fluid & electrical characteristics and thermal gradients
• Measurements are compared to their limits.
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Terminology
Reliability Centered Maintenance (RCM):
• A systematic, disciplined process to ensure safety and mission compliance that defines system boundaries and identifies system functions, functional failures, and likely failure modes for equipment and structures in a specific operating context.
• RCM develops a logical identification of the causes and effects (consequences) of system and functional failures to arrive at an efficient and effective asset management strategy to reduce the probability of failure.
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Terminology
Functional Failure:
• The System is no longer capable of performing the intended function.
• For example, a pump that is designed to produce 100 gpm at 200 psi is considered to have functionally failed if it can only produce 90 gpm at 200 psi.
Maintenance strategies
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Time based
Wait until it breaks..
Data based
Information based Type of
maintenance
Top
Quartile
Lower
Quartile
Proactive >20% 0%
Predictive >45% ~12%
Preventive >25% ~31%
Reactive <10% ~55%
Sources:
•Society of Maintenance & Reliability
Professionals Survey
•The Business Case for Reliability
Robert DiStefano, John Schultz
(Eff
ec
tive
ne
ss
)
Org
an
iza
tio
n &
Av
aila
bilit
y
Maintenance Cost Expenditures
Preventive
Reactive
(Efficiency)
A
B
Predictive
Proactive
>65%
~86%
100% 100%
Maintenance strategies
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$10
$15
PdM PCM PM RM
$20 M
ain
ten
an
ce C
ost
$/h
p/y
r
$5
From EPRI Power Generation Study
Maintenance Strategies
Note: This chart represents established programs
Comparative maintenance spend
Asset criticality ranking
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Asset criticality ranking Asset Criticality ranking helps determine the right level of asset management resources (technology, parts, and people) for each asset. This enables the business risk of each asset to be managed in an appropriate manner.
The Primary criticality ranking criteria are:
• Safety,
• Environment & Regulatory Compliance,
• Production,
• Maintenance & Operating Costs
• Product quality
Plus other criteria if relevant
The criticality ranking process produces a balanced ranking of All Assets in the plant – each with a 4-digit numerical criticality number.
A cross-functional team is usually assembled to agree on criteria weighting and asset evaluation.
Typical Asset Criticality
Ranking Tool
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Asset criticality ranking On the Asset Criticality Pareto Chart, natural “break points” appear to segregate the assets into identifiable criticality classifications
For the most critical assets (typically 10-15% of assets), a Reliability Centered Maintenance (RCM) approach is used to determine the appropriate maintenance strategy.
Critical assets are assessed using Failure Modes & Effects Analysis (FMEA) process.
Less Critical assets are assigned a strategy using standard Templates
Non-Critical assets Run-to-failure
Distribution of Assets
15%
Cri
tica
lity
Ra
nk
ing
30% (typical) 50% (typical) 5%
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Mechanical Asset Example (Centrifugal Pump)
Quantitative PM P-F
Interval 5-8 weeks
• The P-F interval is the interval between the occurrence of a potential failure and the decay into a functional failure • Time can be
measured in seconds, minutes, days, months or years. • P1-Px indicate detectability intervals by various techniques or technologies.
Vibration P-F interval 1-9
months
Wear Debris in oil P-F
interval 1-6 months
Audible noise P-F
interval 1-4 weeks
Heat by touch P-F
interval 1-5 days
P1 P2
P5
P6
F
IR Thermography P-F
interval 3-12 weeks
P3 P = Potential Failure Is an identifiable condition which indicates
that a functional failure is either about to
occur or is in the process of occurring
F = Functional Failure The point at which the asset fails to
deliver to it’s intended purpose
P4
P7
Process Performance Data (highly
dependent on tuning of system /
instruments) ~1 week – 6 months
Time
P
Relays
The P-F interval
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Maintenance Management Maintenance Management is the process of managing failure modes to ensure the asset performs its intended function. This is an integral part of our Customer’s asset management and business processes, directly related to their key performance indicators.
There are four Maintenance Strategies commonly employed, each with particular attributes and suited to certain applications.
Selection of the maintenance strategy should support the objectives of our customer’s business.
Today, the top performers in industry are deploying effective maintenance strategies, supported by technologies, resources and sound procedures to keep their assets performing high on the P-F curve.
Time
Failure Mode #1
F1
P1
Time
Failure Mode #2
F2
P2
Time
Failure Mode #3
F3
P3
The P-F Curves illustrate progression of multiple
failure modes on one machine - from Potential
Failure Initiation (P), to Functional Failure (F)
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Technology Maintenance Strategy
RCM
FMEA
PM Templates
Run to Failure
Protection, on-line diagnostics, process data, performance &
Decision Support
On-line scanning & process data
Off-line portable & process data
Process data
Plant equipment criticality
Protection, on-line diagnostics & process data
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Bently Nevada Solutions Maintenance Strategy
RCM
FMEA
PM Templates
Run to Failure
3500 & 3701, System 1, Bently Performance/EMAP &
Decision Support
Trendmaster DSM & wireless
Snapshot PDC
Plant equipment criticality
3500 & 3701 & System 1
System 1
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System 1 asset management platform
Online - Continuous
monitoring & protection
Critical Assets • Gas Turbines
• Steam Turbines
• Compressors
• Main line Pumps
3500 & TDI 3300 &
TDXNet or TDE
Online – Periodic
(scanning) monitoring
Wired Wireless
Essential Assets • Fans
• Pumps
• Blowers
• Etc…
Snapshot PDC
BOP Assets • Vibration
• Portable Devices
• Lube Oil
• Thermography
• MCA, etc…
Offline – Periodic
walk-around monitoring
Switch/Hub
Questions?
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