A look at reliability centered maintenance
Reliability Centered Maintenance (RCM) for Leak Detection Equipment
LDP should include written procedures to ensure that the LDSs and their supporting infrastructure components are designed for reliability and maintained. This includes instrumentation, communication systems, and processing units (e.g. SCADA/DCS hardware and software, flow computer/PLC, hardware, and software) and backup systems.
The maintenance program may include the following questions.
- What is the function of the particular item and what is its performance standard?
- ln what ways may it fail?
- What happens when each failure occurs?
- In what way does each failure effect the LDS?
- What procedures can prevent consequence of failure (an active prevention approach)
- What may be done if a suitable preventive task cannot be found?
In each LDS, components may require specific calibration hardware, training, and skills to successfully maintain them. Procedures should be followed to ensure that each component is maintained and contributing to the robust and reliable performance of each LDS.
Leak Detection Component Identification
All components integral to the reliability of an LDS should be identified and documented. These components may be physically tagged and/or their corresponding tracking database tags flagged to signify that they are components of the LDS. A common database naming practice for all leak detection database components may be used.
Design
Design for Reliability and Maintainability (DfRM) is a closed-loop process that may use the following approach.
- Gather maintenance data and develop into Reliability, Availability, and Maintainability (RAM) models. Maintenance data may be gathered from the maintenance technicians’ field data collection system, customer surveys, and warranty information. The data are then developed into information that supports decisions.
- Identify and develop maintenance concepts using information from the RAM models. The selected maintenance concept is an important design constraint.
- Design products using selected maintenance concepts. The design process begins using a systems approach and a variety of design tools, design rules, and approaches. At this stage, flexibility is great and design change costs are low.
- Design, analyze, test, and improve/optimize the LDS. Based on the results of analysis and test (a prototype of portions of the product or even the entire system may be built), the design evolves and maintenance concepts are reviewed and revised. At this stage, flexibility decreases and design change costs rise. Engineering finalizes the design and implements the DfRM system. At this point, flexibility to modify the product maintenance features is low and the change costs are high.
- Collect Held maintenance data and develop information. Collect product field data in the form of customer feedback, warranty information, surveys, and service work. The information derived from these data may be used to evaluate the performance of the product in the field and in designing and implementing new maintenance systems. The results of ongoing meter proving may be used to evaluate the condition of the meters.
- Make field improvements as required by safety, economics, and other factors. Initial field performance may be lower than anticipated and there may be additional charges to the design, procedures, or maintenance concept. At this point, modifying the product is very difficult and expensive. Only those changes dictated by customer acceptance or safety or that are economically attractive may be made.
- DfRM process repeats with next-generation products. Based on information generated from the field data.
- The design for the maintainability process is repeated for the next generation product. Design rules may be revised, new tools developed, and design approaches validated or revised.
Redundancy for component failure and maintenance may be provided. This may be hardware redundancy for individual components, backup systems, communication channels, or alternative operating procedures. For example, redundant sensors may be made active while the primary is offline for calibration, maintenance, or replacement. The pipeline operator may evaluate the process by which a redundant system or component becomes active. An automatic cut-over to the backup/redundant system or component is one approach. The use of an alternate operating procedure is another approach.
Field instrumentation should provide the required accuracy and repeatability for leak detection under all operating conditions. Look at the maintainability. Address software maintenance activity in the field as patches, upgrades, and new software revisions are deployed. A complete maintenance picture includes defining scheduled maintenance tasks and assessing impacts on LDS availability.
References
- American Petroleum Association. (2014). Recommended Practice 1175, Pipeline Leak Detection Program Management (2st ed.). Washington, DC: Author.
A Look Inside API Recommended Practice 1175 Series
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