Concepts Tasks Settings Glossary of MTA2 Terms The following terms are used throughout the MTA2 topics. For a full glossary of APM terms, see Glossary. Term Definition Action Plan An action plan in a strategy development analysis identifies an asset’s failure mode and recommends an action to prevent the failure or mitigate its consequences. For example, MTA2 and SIF action types are condition-based maintenance, failure-finding maintenance, scheduled restoration or discard, modification or redesign, and no scheduled maintenance (run to failure). RBI analyses support actions such as inspections, strategy, and modification or redesign. Asset Reliability Program An asset reliability program is a set of pre-planned work (standard tasks and standard jobs) for an asset. You can also include triggering rules that define when this work is to be done. Standard tasks and standard jobs that are not triggered may also be included in an asset reliability program. Condition-based Maintenance A task that entails checking for potential failures so that action can be taken to prevent the functional failure or to avoid consequences of the functional failure. Demand Scenario A demand scenario is a situation that requires that an asset, such as a safety device, be put into operation. Examples of demand scenarios are fire, power failure, and blocked outlet. Environmental Consequences A failure mode has environmental consequences if it could breach any corporate, municipal, regional, national, or international environmental standard or regulation which applies to the physical asset or system under consideration. Failure Consequence The way in which the effects of a failure mode matter (evidence of failure, impact on safety, the environment, operational capability, direct and indirect repair costs). Failure Effect What happens when a failure mode occurs. Failure-finding Interval A failure-finding interval is the length of time that it is considered safe to wait before performing failure-finding maintenance. The interval is calculated or estimated based on the desired availability and the frequency of failure of the protective device or system. Failure-finding Maintenance A scheduled task used to determine whether a specific failure has occurred. Failure Mode A failure mode is a single event that causes a functional failure. For example, if a pump’s impeller becomes worn, the pump cannot convey liquid at the required rate. Failure modes are analyzed in maintenance task analysis (MTA2), reliability-centered maintenance (RCM2), and failure modes, effects, and criticality (FMECA) analysis along with the action plans that prevent or mitigate failures. Safety instrumented function (SIF) analyses examine the risk of failure in safety devices, the effects and consequences of failure, and ways to reduce risk by putting safety provisions in place. For risk-based inspection (RBI) analyses, the failure of concern is loss of containment of pressurized equipment items. Examples of failure modes are small hole, crack, and rupture. Failure Mode Consequence Priority A failure’s or failure mode’s consequence priority provides an indication of the relative importance of the asset failure. The larger the number, the greater the severity of the failure. The priority can be used to recommend root cause analysis for a failure or to determine the order of action plan implementations. Consequence priorities are assigned to failure modes during risk assessment. In failure evaluation, the consequence priority is used in the calculation that determines whether the failure is suitable for root cause analysis. APM assigns the consequence priority by comparing the information to a set of customer-defined rules. The consequence priority rules can be based on the failure severity, relative risk (risk analysis only), failure costs, downtime costs, downtime, or a combination. For example, the Extreme consequence priority could be assigned to failures or failure modes whose total severity is greater than 25 or failure costs are more than $25,000. Function What the owner or user of a physical asset or system wants it to do. See also Primary Function and Secondary Function. Function Group A function group is a way of identifying assets that are responsible for performing a particular function. For example, the “Pump Assembly” function group could be used to indicate the relationship between a centrifugal pump, 20 HP motor, and valves. Maintenance Task Analysis Maintenance task analysis (MTA2) is APM’s unique strategy development methodology that enables the analysis team to quickly create and implement basic, technically-sound reliability programs. MTA2 is most effective when operational and maintenance knowledge about assets is well-documented and consistently used by employees. MTA2 provides an alternative to the resource-intensive RCM2 analysis, while still allowing you to identify the right work to improve performance across the plant. MTA2 methodology and tools allow the analysis team to: • Identify the assets to be analyzed • Identify the causes of asset failure • Recommend actions to prevent or mitigate failures No Scheduled Maintenance A failure management policy that permits a specific failure mode to occur without any attempt to anticipate or prevent it. Also referred to as “Run-to-Failure”. Non-Operational Consequence A category of failure consequences that do not adversely affect safety, the environment, or operations, but only require repair or replacement of any item(s) that may be affected by the failure. Operating Context The operating context is the circumstances in which a physical asset or system is expected to operate. Operational Consequences A category of failure consequences that adversely affect the operational capability of a physical asset or system (output, product quality, customer service, military capability, or operating costs in addition to the cost of repair). P-F Interval The PF interval is the time between the point at which a potential failure becomes detectable and the point at which it degrades into a functional failure. Primary Function The function that constitutes the main reason why an asset or system is acquired by its owner or user. Reliability Strategy Selection Reliability strategy selection (RSS) analysis applies a set of criteria to an asset to determine the most appropriate plan for improving its reliability. The analysis team uses the Reliability Strategy Selection questionnaire to perform, document, and review analyses of system-level assets. Possible strategies are to implement (or continue) basic care, perform maintenance task analysis, perform RCM2 analysis, or escalate the asset risk to stakeholders for further consideration and action. Run-To-Failure A failure management policy that permits a specific failure mode to occur without any attempt to anticipate or prevent it. Referred to in APM as “No Scheduled Maintenance”. Safety Consequences A failure mode has safety consequences if it could injure or kill a human being. Scheduled Restoration/Discard A scheduled task that entails restoring or discarding an item at or before a specified age limit, regardless of its condition at the time. Secondary Function Function that a physical asset or system has to fulfill apart from its primary function, such as those needed to fulfill regulatory requirements and those which concern issues such as protection, control, containment, comfort, appearance, energy efficiency and structural integrity. Strategy Development Analysis Strategy development analyses are methodologies for evaluating asset priority, defining asset functions, determining how failures occur (failure modes), evaluating the risk of asset failure, and preventing or mitigating the effect of failures. The varieties of strategy development analysis include: • Asset Prioritization Analysis • Current Practice Review (CPR) • Design FMECA • Reliability Strategy Selection (RSS) • Maintenance Task Analysis (MTA2) • Reliability Centered Maintenance (RCM2) • Risk-based Inspection (RBI) • Safety Instrumented Function (SIF) Analysis • Hazard and Operability (HAZOP) Analysis Strategy Development Analysis Template A strategy development analysis template is a group of settings that can be used as the basis for a strategy development analysis (MTA2, RCM2, SIF, or HAZOP). A template identifies failure modes for a type of asset, rather than for a specific asset. Similarly, it refers to indicator templates and task templates, not to specific asset indicators and standard tasks. It includes an operating context for assets and a maintenance strategy for each of its failure modes. In addition, an RCM2 template identifies functions and functional failures. Susceptibility to Failure Evaluations Susceptibility to failure evaluation examines the asset’s non-age related degradation patterns. It can provide an alternative to probability of failure analysis for these failure modes. For example, susceptibility evaluation can be used to determine the vulnerability of atmospheric storage tanks to corrosion under insulation or stress cracking. The evaluation can result in recommended actions, susceptibility ratings, or both. Time Between Failure The length of time between failures (TBF) is used in three ways in APM strategy development analyses: • The time between occurrences of the failure (TBF) when inspections and/or preventative maintenance are performed. This value is recorded in failure statistics. • The estimated length of time between failures (ETBF) when no preventive maintenance is performed on the asset. This value is sometimes used to determine probability of failure in risk analysis. • Estimated time between consequences (ETBC) – The time between unexpected consequences or failures when inspections and preventive maintenance are performed on the asset. APM calculates the mitigated (or residual) risk using this value when maintenance feasibility is evaluated.
