A Possible Application of Reliability Centered Maintenance
Principles
in the Design, Construction
and Operation
of
High Speed Vessels
Richard S. PlossABS Americas, Houston, Texas
ABS2RACT
High speed vessels offer cost eflective options for short-haul surface transportation in regions with navigable waterways and heavily congested surface arterials (kuch as those existing in the Puget Sound). Today’s proven technology in construction materiais (aluminum, composites, or combination thereo~ combined with a wide varie~ of propulsion options (diesel, gas turbine, Z drive, water jets, etc.) have led to concepts ranging from high speed low wash passenger-only vessels to conceptual high speed vessels capable of open ocean transits at speeds of 40 knots with payloads of 800 tons. Technological advances enable the optimization of factors such as speed payload, endurance, and maintenance actions. A concept is presented to use Reliability Centered Maintenance (or RCM) in conjunction with an existing ABS Guide to satisfi Special Continuous Survey of Machinery requirements. A proven forty year concept, RCA4 combines design and maintenance requirements to controI maintenance costs and reaiize enhanced operational reliability. In the airline industry, the annual overhaul cost of a Boeing 747 aircra~ (an RCM design) when compared to the DC-8 (a partial RCA4 design) was $60 million less in 1984 dollars with additional savings (again in 1984 dollars) of $5 million in reduced engine overhauls. The paper shows how RCA4 concepts could be used with existing ruies and regulations to obtain: (1) use of approve maintenance plans to satisfi the mwimum number of survey items; (2) greater designer jlexibiiity in selection of the propulsion plant; or (3) procurement of vendor-supplied equipment and material that give the best returns for the intended service [e.g., greater revenue enhancements, higher reliabili~, lower maintenance costs, enhanced safety, e.g.].
INTRODUCTION
RCM is a disciplined philosophy to maintain the environmental, operational, and safety performance levels necessary to accomplish a vessel’s purpose. These performance levels are initially established during design. RCM reviews the design to identi~ possible failure modes, their consequences, and to identifi preventive actions through maintenance. It focuses on maintenance or, in cases where maintenance could not effectively restore performance, redesign.
A well documented and properly conducted RCM program can integrate the necessary actions, to optimize a vessel’s safe and reliable operation which is a point of prime interest to a classification society.
The results of an RCM program can be realized very quickly by an owner if applied correctly, and the
potential savings are substantial. RCM has been practiced extensively in the airline industry. The benefits documented by operators of regulatory compliant ‘products’ are shown below. It should be noted that these cost savings are in addition to increased operational availability that, in the commercial aviation industry, resulted in enhanced revenue.
- $60 (1984 dollars) million savings in overhaul costs of Boeing 747 airplanes (an RCM design) compared to the McDomell Douglas DC-8 (a partial RCM design)z,
- $5 million (1984 dollars) annual savings in 747 engine overhauls3.
- $100 million savings in submarine overhaul costs when RCM was used to extend the overhaul cycle from six to twelve years,
The American Bureau of Shipping (ABS) 1995 Guide for Survey Based on Preventative Maintenance Techniques allows the crediting of properly conducted preventative maintenance (based on an ABS approved maintenance plan) to satis~ Special Continuous Survey of Machinery requirements. It also provides for special consideration by ABS in the application of condition monitoring techniques other than those addressed by the Guide.
Reliability Centered Maintenance (RCM) can be used to help develop the maintenance plan intended to satisfy the maximum number of survey items, and to provide data to support the extension of machinery
overhauls beyond the five-year cycle, and eliminate unnecessary maintenance tasks.
It is recognized that a reader’s experience with, and knowledge of, RCM principles will determine his comfort level with the ideas presented. It is outside the scope of this paper, however, to describe the RCM philosophy in detail and only its major concepts are presented
1- DEFINITIONS AND APPLICATIONS The definitions and application of terms used in this paper are identified below:
Term Definition Application
‘ABSPM 1995 Guide for Survey Based on Preventative Usage refers to the document as a whole Guide’ Maintenance Techniques
‘Availability’ ameasure of the amount of time the equipment is As used in ‘Performance’. Sometimes called
capable of operating4 uptime.
‘Condition the various technique to detect a potential failure Condition monitoring is used in the context of Monitoring’ condition and monitor that condition over a on-condition techniques.
period of time.
‘Efficient’ productive of desired effects; productive without As used in ‘Efficiency’ wastes
‘Efficiency’ e~cient operation As used in ‘Performance’
‘Function’ the action for which a person or item is speciaily The capability of an item that is a specific flttedor used, or for which an item existf requirement of its design7.
‘Performance’ theprocess or manner of carrying something into Operating Performance is the product of
effect ‘availability’, ‘efficiency’ and ‘yield’ to
accomplish a given fimction or task; capability ‘RCM Reliability CenteredMaintenance @CM) is a As defined
process used to determine what must be done to ensure that any physical asset continues to fulfill its intended fimctions in its present operating contexf
‘Reliable’ suitable orflt to be relied on As used in ‘Performance’. Consistently good in quality or performance
‘Risk’ possibility of loss or injury Probability that an item’s capability remains above a specified level of performance ‘Special the use of a properly conductedABS approved As used in the ABS ‘1995Guide for Survey Continuous preventative maintenance plan to accomplish Based on Preventative Maintenance Survey’ Special Periodical Survey requirements in a Techniques’
regular rotatiqn within aflve year period.
Term Definition Application ‘Yield’ a measurement of how much of a machine’s As used in ‘Performance’. It is the
i
output conoorms to the required quali~ percentage of uptime the equipment can
standard provide the service at the required standard.
2- HIGH SPEED CRAFT REGULATIONS AND RULES
The International Code of Safety for High-Speed Craft (HSC Code) is contained in Chapter X of the Safety of Life at Sea Convention 1974 as amended (SOLAS). The purpose of the HSC Code is to allow appropriate sdety considerations be given to High Speed Crafts, whose mode and operations are in many respect distinct from that of conventional ocean-going cargo and passenger vessels. Due to the relatively limited experience of operating such vessels, the IMO HSC Code specifically call out alternative approaches to augment the traditional prescriptive methods used in the Code.
ABS published the Guide for Building and Classing High Speed Crofts initially in 1990. This guide identifies standards based on the design practices and various types of hull design in use at time of publication. The current version incorporates the needs high-speed passenger craft industry and operators have identiled to ABS. It speeifies machinery requirements and hull construction requirements based on three different materials used in the design of high-speed vessels; namely, steel, ahuninum alloys, and fiber reinforced plastics. Where applicable, the HSC Guide references the appropriate Rules for Building and Classing Steel Vessels.
The regulations applicable to high speed vessels designed and constructed in the United States depend whether their service will be international or domestic. TheHSC Code applies to high-speed vessels engaged in international voyages. 1] This code is an inclusive set of requirements for building and operating high speed craft, which is an advantage to a design team.
3- ABS 1995 GUIDE FOR SURVEY BASED ON PREVENTAm MAINTENANCE TECHNIQUI?S
This document (hereafter referred to asABS PM Guide) allowsthe use of a properly conducted and ABS approved maintenance plan to accomplish the following objectives:
1. Sati@ the requirements of Special Continuous Survey of Machinery.
2. Justify the extension of machinery overhauls beyond the normal five-year cycle.
3. Incorporate Condition Monitoring techniques beyond those referenced in theABS PM Guide. The benefits of using theABS PM Guide are:
1. Savings inmaintenance cost and time.
2. Increased operational time. 3. Enhanced reliability.
4. Better or faster ways to ident@ sdety coneems and their resolution.
4- RELIABILITY CENTERED MAINTENANCE CONCEPT OF FAILURE AND RELIABILITY
RCM is a top-down rnaintenanee philosophy that starts with identification of an item’s functions and progresses downwards to the lowest fimctioml level necessmy to optimize reliability.
Often reliability is thought of in terms of when something has broken failed, or will not work. RCM, however, defines reliability in terms of an item’s capability to meet a design standard. ‘Inherent reliability’ as used in RCM can only exist when an item’s capability exceeds the performance level necessa~ to accomplish a speeified function.
Failure in RCM is defined as the inability Of any physical asset to meet a desired standar> of performance. 12 Only when an item performs below its criteria does ‘failure’ occur. Because an unsatisfactory condition can be perceived differently by an owner, operator, designer, erailsmarL or surveyor, performance levels (or standards) need to be established by operations and engineering people working together. ]3 For this reaso~ the ability to identi~ failure with respect to a desired standard of performance is more important than defining a failure’s technical characteristics. The goal of RCM is to identi~ all potential failure modes and their consequences, and to develop tasks (or procedures) which prevent or minimize the possibility of their occurring.
Consequences of Failure can be classifkd into four categories. 14
- Hidden Failure. A failure where the consequence has no direct (or immediate) impact but has the potential to expose the vessel to multiple failure of serious consequences.
Example 1: The failure of a sprinkler system’s activation switch would result in a degraded performance that would not be noticed until the system is needed. RCM addresses solutions to such failures in three steps: (1) establish a level of probability acceptable to the organization (operator or classification society); (2) determine the probability that the fimction will fail during the period under consideratio~ and (3) determine the availability the hidden function
must achieve to reduce the risk of multiple failure to the required level.
- Safety and Environmental. A safety failure is one whose consequence is injury or death. An envirorunental failure is one whose consequence may result in a breach to a corporate, regional, national or international environmental standard. RCM stipulates that this category of failure must be identitkxi and prevented through the use of preventative maintenance actions or redesign. Example 2: A few examples of what constitutes this failure are: electrocution, falling objects, disintegration of large rotating components; the collapse of structures; or flooding.15
- Operational. This is a failure which has operational consequences by affecting items such as customer service, operation costs, schedules. Example ~: The purpose of a propulsion cooling system is to remove a specified amount of heat at a certain engine load under a set of given environment condition (e.g., seawater temperatures). Failure would occur from the designer’s perspective when, for whatever reaso~ the system cannot remove the specified amount of heat. Fouling of a cooling tube bundle or a worn pump may not prevent an engine from operating at the required performance levels to maintain a schedule when
the ship is in cold seawater even though the system is incapable of removing the specitled amount of heat. Failure by an operator under such conditions is wt observed. Failure might however, beobserved when the ship is operating in warmer waters such as the Indian Ocean in the
summer months and cannot produce the speed necessa~ to maintain a schedule.
Non-operational. These are failures which do not a.tTectsafety nor operations and only involve the cost of repairs. The consequences can be thought of as economic as they are only associated with the direct costs of repair. It may be that, in such scenarios, it is cost effective to allow a component to ‘fail’ than to perform preventative maintenance.
Example 4: Assume that the propulsion cooling system has one primary and one secondary cooling pumps. Suppose the expected failure rate of a bearing on the primary pump is once every three years, and that the cost to replace it is
$2,100.
Assume that an audible noise monitoring program was implemented on a weekly basis at a cost of $20 per check. The cost to do the monitoring ($20 x 52 x 3 = $3,120) is greater than the cost to replace the bearing ($2, 100). It would not be cost effective to implement preventative maintenance program knowing that the secondary pump is capable of providing the necessary cooling flow while the primary pump is being repaired.5- FUNCTIONS
Given that RCM must interface with the design process, there needs to be a common meaning of the terms ‘criteria’, ‘failure’, ‘fimction’, ‘purpose’, and ‘performance’. Performance-based design and its requirements have much in common with that of RCM. A good starting point in understanding these terms is to compare perfo-~ce based requirements with non-performance-based requirements.
Area of Comparison Performance-Baaed Non-Performance-Based Requirements Requirements
Purpose Describes the fimctions the product is to Describe how product is to be designed
perform and manufactured
Key Criteria Describesthe means for veri@ing Describe means for ensuring specified
performance processes followed
Design Latitude Given to Allow the supplier (builder) to determine Force the supplier (builder) to use Supplier (Builder) the best way to achieve results prescribed methods and approaches Responsibility Responsibility for results clearly belongs Responsibility for results is shared by the
to the supplier (builder) customer and supplier (builder)
Table 2 Performance-Based versus Non-Performance Based Requirements’G
Note that ‘function’ is used in Performance-Based used to describe the means (or standard of judgemen~ Requirements to describe the product and ‘criteria’ is to verify the required level of performance is met.
198
‘Function’ is a design requirement ofwhat we want an item to do (e.g. desired performance. Usually determined by the design team and the RCM Review Group (described in Section 11), fi.mctions are categorized at dMerent levels by their degree of importance. An example of primary and secondary fimctions is shown below:
- Primary functions are speed, payload, range, accommodation arrangemen~ and customer service.
- Secondary functions are engine size, safety, ship control, Comfom structural integrity, environmental compliant mooring, and navigation.
There are fimctions other than primary and second~ ones which would be categorized at lower levels such as bunkering, storing and towing.
Use of documents such as one from the United Kingdom in 1997 of a formal safety assessment for high speed vessels can help identify important functionsl’. Seventy-two fictional systems, features and other technical factors which directly influence the safety associated with the functions of high speed vessels are listed in six categories. Appendix A contains a partial listing of those items.
6- PERFORMANCE LEVELS
Performance levels are necessary to an RCM maintenance plan. They can be categorized as:
System Initial Performance (SIP) is that performance or material condition which corresponds to the ‘as designed’, ‘as built’ or ‘as overhauled’ condition of the system including subsequent alterations. The SIP represents the best performance level or material condition to which the system could be refurbished with design changes.
System Mission-Limiting Performance (SNIP) is that level of performance or material condition below which successful completion of the vessel’s mission would be jeopardized. The SNIP represents the baseline value to be used in determining the satisfactory performance level or material condition of a system
System Reliability-Minimum Performance (SRP) canbe greater or less than SMP. It is that performance level or material condition below which the system:
- Ceases to perform its design timction although the vessel’s mission is not jeopardized.
- Becomes uneconomical to repair or requires major expenditures to repair.
- Expenditures would be considered excessive when the dollar value to repair exceeds the initial cost (adjusted for inflation)
System Safety-Minimum Performance (SSP) is that performance level or material condition below which human life is endangered. There are some systems
which can fail completely without endangering human life and those will not have an SSP.
7- USE OF PERFORMANCE LEVELS
The performance levels are derived from a system or component’s requirements ofwhat we want an item to do. There is an important distinction between what we want an item to do and what the item can do (e.g. its capability). The difference between the two is what determines reliability. 18 An item can only have reliability if its capabi/i& is greater than its desired performance.
Fig 1 Propulsion System Functional Performance Figure 1 shows how performance levels are used. Here an owner has specified a performance requirement of a speed no less than 32 knots twelve months after the last time the hull was cleaned. A performance level (criterion) equivalent to the owner’s requirements is established. The ditTerence between the propulsion’s performance level (or capability) at any given time and the criterion represents the system’s inherent reliability at that point in time.
Performance levels can be used to assess safety, for those systems where a safety minimum performance (SSP) has been established, in the same manner as reliability is assessed.
The ‘P-F Interval’ is the time between the on-set (or occurrence) of potential failure and its decay to functional failure. This internal governs the frequency at which on-condition tasks or maintenance actions must be performed.19
8 - PREVENTATIVE MAINTENANCE AND
CONDITION MONITORING
Preventative maintenance and on-condition tasks are used to assess performance and determine material condition. The terms ‘on-condition tasks’ and ‘condition monitoring’ are often used interchangeably. This paper shall treat the two as one and define ‘condition monitoring’ as comprising the following techniques: 20
condition monitoring techniques
- primary effects monitoring techniques
inspection techniques based on the human senses A maintenance plan developed using RCM will ident@ clearly how condition monitoring and preventative maintenance tasks interface with each other to eliminate or minimize the risk of fictional failures. The data collected from these tasks is used to assess condition and system petiormance, and to determine if the observed (or calculated) degradation compares with predicted values.
A ‘strength’ of RCM is that timely corrective action can be taken when performance levels unexpectedly fail to meet criteria or when an unacceptable trend is noted, especially with regards to safety. Either of these conditions initiates a decision making process to determine if increased maintenance frequencies are necessary (and acceptable) or if corrective engineering is required. The availability of analyzed RCM data can be invaluable in documenting when corrective engineering are the best course of action.
9- SYSTEM PERFORMANCE “
Examples are given of how ‘criteria’, ‘performance levels’, and ‘reliability’ are used to determine a system’s performance.
Example 5- Propulsion System.
A propulsion system’s efficiency degrades due to factors such as reductions in the capability of the prime mover, fouling and roughening of the hull, or roughening of the working sections of the propeller caused by cavitation or erosion21.
II
RPM
Fig 2: Engine Performance Limits
Figure 2 shows an engine’s operating envelop as a fimction of its performance limits: the Mean Effective Pressure (MEP), Rated Power ( 100VOPower), air lirni~ and minimum load. An engine operating outside this envelop is subject to degraded performance due to a
variety of factors: accelerated wear due to generation of heavy smoke; exhaust system fouling, combustion chamber and turbocharger fouling, or turbocharger surging.
RPM
Fig 3: Propulsion System Performance
Figure 3 shows how a propeller can afTect performance. Here the sustained thrust power is super-imposed on the engine’s performance limits (e.g., its operating envelop). Also super-imposed are two propeller cumes where the pitch of propeller B is greater than that of Propeller A. If one enters Figure 3 at the sustained thrust power level and follows it to the righ~ it will be noted that an engine coupled to Propeller B must operate at 84% MCR (or at 89% MCR when coupled to propeller A), to generate the required thrust. The system’s reliability depends on what the desired performance is. In this example, reliability is relatively the same (9-100/.) but for different spectrums of performance. At first glance Propeller B appears to be the better choice as the engine genemtes the desired performance of 32 knots using less power than if Propeller A were used. The fuel consumption with Propeller B would be less than with Propeller A. Propeller B will also generate a greater thrust at lower engine rpm’s than will Propeller A, which is an asset during low speed maneuvering evolutions. Notice, however, that Propeller A will generate more thrust (and hence higher speeds) without overloading the engine and hence has more value in those situations where reserve power may be desired to regain schedules.
An engine manufacturer might speci@ an acceptable overload condition (provided it is below the MEP Limit) for a given period of time under specified conditions. This is illustrated in Figure 3 where the maximum allowable engine overload condition is set at 104% MCR. Even though the engine should be able to operate at 1040/. MCR, Propeller A starts to overload the engine at 102’?4.and Propeller B at 94% MCR; in
200
this example, Propeller A allows the system to generate more thrust to obtain higher vessel speeds without violating the manufacturer’s operating parameters. Thrust can also be reduced by factors such as a fouled hull which will cause propeller curves to ‘move’ to the left and overload the engine.
It should be apparent that the maintenance and monitoring tasks for the same engine would be different given the propeller selected.
Ekample 6- Pressurized Piping System.
This example shows how a pump can meet a system requirement but with varying degrees of reliability.
New PUIIP Heed Copoc, ty (SIP) Wovrn P“mP Head Cope, ty (SUP>
Reliability E (SMP) t t \ Tc,tol Stat!C He. d \ + Flow Rote
Fig 4: Effect ofPump Wear on Performance Piping system curves depict head (e.g., pressure) losses as a fimction of flow rate, piping elevatiow and friction losses (which accounts for head loss). These losses are caused by factors such as: roughness of a pipe’s interior surface; head (pressure) losses due to control valves (2-way or 3-way) position; variable operating parameters (such as minimum, continuous and maximum system flow rates); and calculation inaccuracies. A piping system might have a variety of system curves as indicated below:
- Curve A-B is the system curve for a restored (e.g., cleaned) system
- Curve A-C is the system cwve for a newly constructed system
- Curve A-D is the system curve for a corroded system
- Curve A-E is the minimum acceptable condition (e.g., maximum acceptable head and flow rate losses due to valve leakage and corroded / clogged lines).
Super-imposed on the system curves are the pump head curves for a new and worn pump, The new pump’s capability is represented by the line ‘s’-’t’, and a worn pump’s capability is represented by the line ‘r’-‘w’. The system’s functional requirement might be a head and flow rate as defined by point ‘w’.
Reliability exists so long as the required capability (indicated by the area ‘r’, ‘s’, ‘t’, ‘w’) is greater than tie system’s desired petiormance (represented by the line ‘r’-’w’).
The criteria selected would probably be along the line ‘r’-’w’. The system would sati~ its fictional requirements so long as the monitored head and flow rates are to the right of the line ‘r’-’w’.
10- RCM MAINTENANCE PLAN OBJECTIVES The objectives of an RCM maintenance plan that would maximize its ability to be incorporated as part of the Special Continuous Survey process should be to:
1. 2. 3. 4. 5. 6. 7. 8. 9.
Identi& the vessel’s functions.
Identi@ the performance levels required to accomplish those functions,
Identify the systems needed to provide the performance.
Determine the criteria to veri~ performance levels.
Determine how a system may fail to fulfHl its fimctions
Identi~ the causes of each fictional failure Determine the consequences of failure Identi~ actions to prevent failure
Identi@ situations for resolution where maintenance cannot deliver the desired performance. (A mandatory action when safety issues are involved.)
The RCM Review Group will be involved with all of the objectives, but the first four are normally the responsibility of the design team and opemtor.
11- RCM REVIEW GROUP
An RCM Review Group is used to review requirements, develop a maintenance plan and then monitor the plan’s effectiveness. The members should be persons trained and experienced in the use of RCM. The working group can be as small as two persons (one from a maintenance fimction and one from the operations functiow but ideally it would be comprised of 1. RCM Facilitator 2. Operating Supervisor 3. Engineering Supervisor 4. Operator 5. Craftsman
6. Technical or Process Expert 7. Surveyor
12- MAINTENANCE PLAN DEVELOPMENT There are two strategies an owner / operator can consider when implementing RCM22. Both will produce the same quality of technical results, the
of the results enduring due to the expenditure of greater resources in terms of people, training and time.
Strateg 1 Short Term Approach. The focus is on assets and processes to achieve results in the shortest time. This approach concentrates on either: (1) specific problems of an intractable nature having serious consequences; or (2) focusing on those assets which are most likely to benefit from RCM. Its benefit is a quick process that is easy to manage. The number of persons used, and the amount of training required is small. The disadvantage is that the persons involved in developing RCM often have no long term involvement nor commitment with the risk that the results are much less likely to endure.
Strate~ 2 Long Term Approach. This strategy
focuses on developing ownership of maintenance problems and their solutions for the purpose of obtaining results which are far more likely to endure. The advantage is that it develops teamwork and individual motivation at all levels, helping to create an organization that feels RCM “is the way we do things around here”. The disadvantages are that it is a slower process, takes more resources, requires a substantial amount of training, and is more difficult to manage.
Development of an RCM Maintenance Plan using one of the above strategies should be a minimum cost program using only the information available at the time23. It should be composed of tasks using the minimum of tools to focus maintenance resources on items critical to the safety, reliability and operations. It is the responsibility of the RCM Review Group to collectively make this happen.
The steps to develop an RCM program offering the greatest opportunity to save money are listed below. Use of these steps can are also identify areas (or even projects) where RCM may not provide cost savings.24 Step 1: Design for Maintainability
Design, technical, maintenance, operator technical knowledge and expertise is incorporated with that of shipbuilders and vendors to identi@ inspections which can be made with the fewest tools possible. It should match the expected or known failure rate to a preventative maintenance (PM) schedule. The indicators of failure (gauges, alarms, wear indicators) are identified and provided for. Risk assessments are made to ensure proposed maintenance action will not inadvertently induce more failures.
Step 2: Perform Functional Failure Mode Analysis All possible modes of failure (safety, economic, operational, hidden) are identified as well as their consequences. Processes such as Failure Mode and Effect Analysis @MEA) and Fault Tree Analysis are used during this step.
All high speed craft functions must be clearly identified.
Step 3: Categorize the Failure Distributions
The probability of failure is determined as to when wear-out or deterioration is anticipated to start and what is the effectiveness of repairing / overhauling components.
Step 4: Determine Maintenance Task Intervals. Maintenance tasks are prioritized and their periodicity are established. Only tasks which will maintain a performance level are included. Maintenance tasks associated with on-condition monitoring (where tasks can be inspected, measured, or observed in a non-intrusive fashion) of failure prone parts are given the highest priority, followed by those tasks which are intended to restore a part to its ‘like new’ condition. Removal and replacement of failed components and inspections for undetected failures are given lower priorities.
Development of a maintenance task should not be deferred when necessa~ data is not available. The RCM Review Group should combine the expertise available with conservative decision to develop the task and annotate it for later data collection efforts.
Step 5: Package All Tasks into an Implementation Plan.
The maintenance tasks are assembled into a maintenance plan. Those tasks with similar intervals are grouped to a common maintenance interval assignment, such as a drydocking or a period when equipment needs to be ‘open and inspected’.
An important consideration in grouping the tasks is to look at the signitlcance of the maintenance tasks and as well as their intervals. Some tasks are to prevent failures of safety or great economic consequences; others are to prevent failures of less serious consequences. The intervals of the tasks addressing less significant consequences are lengthened or shortened to correlate with those addressing more significant consequences.
Step 6: Optimize Results with Data Collection Efforts.
Trend analysis is performed to veri~ equipment is degrading is at an acceptable rate. Data is analyzed to venfi the assumptions made in the initial PM schedule development. Tasks and their frequency of performance are adjusted as necessary to optimize availability and expenditures.
202
Step 7: Analyze Results for Potential Corrective Action.
The tasks and their frequencies are reviewed to determine if the results obtained are economically worthwhile. Adjustments are made as necessmy.
Redesign is considered for any item whose ftilure modes cannot be reduced to an acceptable level with PM. It is mandato~ for those failure modes which cause safety consequences which cannot be redueed to an acceptable level with a PM task or combination of tasks.
13- ANNUAL MAINTENANCE REPORT
The RCM Review Group should prepare an Annual Maintenance Report format for submittal with the maintenance plan to ABS for approval. The format should be sufficient in detail for ABS to assess the data collected and its analysis will be stilcient to sati~ the requirements of the Special Continuous Survey of Machinery.
The report shall have two parts: one for the ‘Planned Maintenance Program’ and one for the ‘Condition Monitoring Program’.
14- FEEDBACK
Accomplishment of Steps 6 and 7 in Section 12 allow the operator (or maintenance supervisor) to veri& the data collection effort is properly focused. It can be expanded or contracted as appropriate.
Feedback from data trends allows the frequeney of maintenance tasks to be adjusted as neeessmy to optimize availability and minimize expenditures.
It can also ver@ if the expeeted benefits are being realized, and if not, identi~ the contributing causes so that appropriate corrective action can be taken that has the best eeonomic return.
15- BENEFITS
The benefits tlom using RCM to satisfy the Special Continuous Survey requirements are similar to those of any RCM program consequently they are extraeted from an RCM publication. These benefits are:25
- An enhanced understanding of how the vessel performs.
- A better understanding of how the vessel could fail and identification of the root causes for each failure.
- Greater safety and environmental protection - Improved Operating Performance due to higher
vessel availability and greater equipment efficiency.
- Greater maintenance cost effectiveness through a focusing of resources on those items critical to the safety, reliability and safe operation of the vessel by elimimting redundant or none required tasks.
- Longer useful vessel life due to foeused emphasis on condition monitoring teeh.niques. - Greater safety and environmental integrity. The
systematic identification of every evident safety and environmental failure and their implications forces these items to become top priorities. - A greatly improved general understanding of the
equipment in its operation eontext.
- ‘Ownership’ of maintenance problems by persons other than the craftsmen or maintenance
DRAFT Appendix A
Possible High Speed Craft Functions
A partial list of functioml systems, features and other technical factors identified by the United Kingdom as directly influencing the ability ‘to provide for the safe and commercially viable international transport of payload using ships within a marine environment’. These are extracted from Section 4, Amex B, of a Formal Safety Assessment prepared by the Sub-Committee on Ship Design and Equipment, 41s’ Session Agenda Item 5, DE 41/INF.7, 12 December 1997. Possible functions are identifkxl initalics; primmy by (P) and secondary by (S)
Technical - Auxiliary Power
Generation, Storage and Distribution (S) - Bunkering - Communications @) - Control (P) - @namic Support ~) - Emergency Response @) - Habitable Environment @) - Layout@ - Maneuvering @) - Mooring (S,) - Navigation (S.) - Payload Loading /Rearrangement I Unloading
- Payload Protection and Care - Pollution Prevention ~) - Propulsion ~) - Propulsion Power Generation@) - Propulsive Power Transmission - Ride Control@) - Safety (P) - Stability (P) - Static Support @) - Storing
- Structure -Hull and Superstructure - Towing Managerial - Administration - Authorities - Business Planning - Commissioning and
Re-commissioning - Construction ~) - Commercial Control and Finance - Coqmate Responsibility - Design (P) - Decommissioning and Disposal - Disaster Planning (P) - Docking@) - Fleet Operations - Maintenance ~) - Pollution Prevention and Management @ - Port Operations - QualiyAssurance (1) - Refit - Regulators - Rescue Operations ~) - Resource Management
(Manning & Persomel) - Repair
- SaJe~ (P)
- Sales and Marketing - Salvage
- Ship Operations @) - Specifications - Survey @) - Training @)
Environmental Regulatory and Legislative
- Berths - Corporate
- Breaker’s yard - Design ~) - Canals /Locks - International @) - Coastal Areas - National @) - Current (tide) @) - Operation ~) - Docks
- Environmentally Sensitive Areas ~) - Emerg ‘y Situations (P) - Fog
- Harbor - Humidity - Ice ($)
- Lakes
- Open Sea or Ocean - Polluted Air and /or Sea
Environment - Ports
- Port Approaches (entering / leaving) (S) - Protected and Partially
Protected Waters - Precipitation - Restricted Areas
(buoyed areas, shipping lanes, etc.) - Riverine areas - Shipyards - Temperature extremes (s) - Salinity extremes - Water depth extremes - Waves @)
- Wind (S)
1Moubray, J,Reliability Centered Maintenance, Industrial Press, New York, 1992, pg 20
2 Grumman Data Information Semites, Inc Reliability-CenteredMaintenance Course Resource Manual,., 1984
3 RCMResource Manual, 1984 4Moubray,RCM, pg 254
5Webster’s Ninth New Collegiate Dictionary, Merrian Webster Inc., Springfield, MA
6 Webster’s Ninth New Collegiate Dictionary 7 Grumman Data, section 2.2.1
BMoubray, RCM, pg7
9 The Oxford Paperback Dictionary, Oxford University Press, Walton Street, Oxford, 0X2 6DP, United Kingdom, 1979
10Moubray, RCM, pg 254
*1International Maritime organizatio~ International Code of Safety for High Sped Vessel, Section 1.3.1 12Moubray, RCM, pg 50
13Moubray, RCM, pg 51
14Strategic Technologies, Inc (STI), Reliabiiity-CenteredMaintenance-An Introduction, ‘Failure Consequences’, Aladon Lt& 1997, pg 4
15Moubary, RCM, pg 63-64
16Reliability Analysis Center,Reliability Toolkit, Commercial Practices Edition, Rome, NY (undated) Table 3.1.1 -l, pg49
‘7 Sub-Committee on Ship Design and Equipment, ‘Formal Safety Assessment Trial Application to high speed passenger catamaran vessels, Final Report” 4 l’t Session, Agenda Item 5, DE 4 l/INF.7, 12 December
1997, Annex B, Section 4 1sMoubray, RCM, pg 44 19Moubray, RCM, pg 118 20Moubray, RCM, pg 121
21Marine Engineering, The Society of Naval Architects and Marine Engineers, Jersey City, NJ, pg 13
22Moubray,RCM,pg241-246
23RCMResource Manual, section 5.3.1 24Reliability Toolkit,pg231
