Plant operators have long considered increased availability coupled with minimized expenses, to be the effective levers to maximize profitability. Traditionally, operators have adopted preventive maintenance practices such as walk-throughs, random checks, and annual shutdowns to prevent equipment failure. While these may help avert some potential issues, studies have found that most of these periodic maintenance checks can be avoided. Preventive maintenance is not only labor-intensive, time-consuming, and prone to human error, but it also does not eliminate the possibility of catastrophic failures. While preventive maintenance practices cannot be eliminated, there is a growing need to gradually evolve to condition-based maintenance strategy.
Condition monitoring offers an approach to monitor parameters and specific events to identify changes in performance or condition of an equipment, or its components, such that remedial action may be planned in a cost-effective manner.
The best way to ensure the successful implementation of Condition-Based Maintenance is to understand the challenges and pitfalls that companies may face when first deploying this maintenance strategy:
- Complex technical environment with multiple protocols, multiple asset types from multiple vendors
- Different assets types are serviced by wide ranging Condition Monitoring systems that are completely disparate from each other. The Maintenance engineer is forced to manage multiple systems, and be familiar with many different user interfaces, simply to fulfill their role; thus, resulting in data overload and information islands which in turn leads to an inability to differentiate and prioritize asset health data automatically and in real time.
- Some facilities still rely on workers to perform manual field observations such as transformer temperatures and power meter readings. Technicians make rounds from one asset to the next, clipboard in hand, checking on its status and reporting on anomalies. This is time consuming and tedious for the Technician, subject to error and omission. It also introduces safety risk and makes it all but impossible to conduct advanced trending or analysis to optimize performance.
- Satisfying the needs of a wide range of stakeholders, ranging from the Plant Manager to the Maintenance Supervisor/Technician to the Plant Operators.
- The ability to access information on the go and act on it (e.g., raise a work order) using handheld devices like smart phones, tablets, etc., is emerging as a critical need for maintenance staff.
A well-executed condition-based maintenance program provides a wide range of benefits, including early warnings of potential failures, reduction in unplanned downtime, reduction in maintenance & inventory costs, support risk reduction with less inspections at heights, confined and remote assets while mitigating the aforesaid. Such a comprehensive system necessitates collaboration between equipment, control, business, and people facilitated by the three key functions, namely Monitor, Decide, and Act as shown in Figure 1 below.
Figure 1: Functional layers of condition monitoring system
Condition-based monitoring solution
Monitor Layer: Monitor Asset Heath for increased awareness
As discussed earlier, any typical plant consists of a wide variety of automation assets, ranging from instruments and valves to drives etc., and production assets like pumps, fans, motors etc. The monitor layer of condition monitoring system leverages multiple built-in condition monitoring engines to automatically monitor the health of plantwide assets in real-time and presents the information in a common and unified dashboard environment, enabling faster and more effective responses to abnormal conditions.
Condition monitoring techniques
Potential Condition monitoring techniques which can be applied for various asset types is described as under :
· Connected Assets: Connected Assets are equipment that continuously accumulates data including which can give insight into its health in near real-time. Such data is often collected leveraging plant SCADA or thru dedicated sensors.
· Intelligent Connected Assets
Vendors are increasingly embedding newer generation connected assets with intelligence to power predictive maintenance strategies. The condition monitor can leverage in-built predictive context awareness to monitor the condition of intelligent assets. Example of such assets are Intelligent Field Device, Drives etc. Such Condition monitoring system usually would be able to scan for new/updated online diagnostic data from monitored assets in real-time, interpret diagnostic data against known conditions and transform it to user-friendly language. Extra information like location data, plant area, NAMUR 107, etc. is added to support maintenance prioritization.
· Non-Intelligent Connected Assets
For non-intelligent automation, condition is monitored using simple or complex rule engines depending upon complexity of the asset. If necessary, additional sensors can be installed to monitor and capture monitor health asset data. The Condition monitoring system will scan for new/updated data from these sensors available via OPC DA, apply simple or complex rules to monitor asset health status. Extra information like location data, plant area, NAMUR 107, etc. is added to support maintenance prioritization.
· Stranded Assets: In older plants, stranded or non-instrumented assets often represent 40 to 60% of asset base which renders data gathering to a manual process. Many of failure contributing causes cannot be digitally monitored. These can only be captured through frequent inspection rounds. Current day mobile workforce system that replaces error prone paper processes with an interactive electronic mobile work process application. The solution includes configurable software and ruggedized handhelds or commercially available off-the-shelf mobile devices that enable creation of inspection and regulatory procedures & data collection. It also will assign, schedule, and execute rounds and report findings that are prioritized based on the level of severity of the issue. The parameters like Ambient temp, Dust, Corrosion, Vibration, Noise etc. that impacts health of any stranded assets is captured through a mobile device. Operators are easily guided through a question and answer process which helps uncover hidden bottlenecks and process or equipment problems. If problems are found, Operators are immediately guided through additional steps or actions to properly identify and address the developing issue. A maintenance alert will be triggered in case of exceptions based on rule base strategy.
Decide Layer: Unified workspace to make smart decisions
One of the primary operational challenges associated with implementing a condition monitoring solution is data overload. This results in an inability to differentiate the relative significance of asset health data in real time so that asset maintenance priorities can be correctly established. This functional layer provides a single unified workspace for plant-wide assets, acting as a “command center” for maintenance. Asset health alerts are presented in an intuitive, easy-to-understand way, with the recommended corrective action. Context is added to alerts to indicate criticality levels using standard such as NAMUR 107 etc. Smart analytics and comparison with historical data help identify failure modes, quality trends, and process issues to reduce time to repair and eliminate unnecessary trips to the field. Comprehensive reporting enables improved shift handovers and status reporting. All this information empowers maintenance to make more informed decisions in real-time.
Act Layer: Unified workspace to make smart decisions:
This layer provides tools to support action on maintenance-related decisions. It includes:
· Mobility to allow quick response from anywhere in the plant
· Workflow options to streamline maintenance processes and eliminate paperwork
The combination of the above three functional layers provides a modular yet integrated condition monitoring solution which is compatible with a wide range of plant assets. The modular design allows solutions to be tailored according to specific needs and budget. Additional components can be implemented and integrated into the overall system as needed
How it all comes together – delivering a Maintenance Command center
Solutions enabling condition monitoring of assets have been fragmented for years. Each system runs in its own island of operation with limited or no interfacing between each other. The new proposed solution integrates multiple condition monitoring techniques as illustrated in figure 2 and providing a unified condition monitoring solution.
Figure 2 How it comes together
Driving profitable reliability, safely
An effective Condition-Based Maintenance solution encompasses the capabilities to monitor the condition of assets, ideally automatically in real time, providing early insight into emerging abnormal asset conditions for better maintenance decision support. It has been shown in practice that Condition-Based Maintenance delivers higher productivity at lower risk.
The top three benefits are:
1. Maximized asset operational uptime
· Detection and avoidance of asset failures
· Shortened time of scheduled shutdowns
2. Minimized O&M cost
· Elimination of wasted effort
· Reduced overtime
3. Maximized workforce productivity and improved safety
· Improved efficiency with effective, fast response times
· Improved collaboration among team members
· Improved safety with fewer visits to the field
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