Driving down maintenance costs
Rationalizing maintenance flows

ABB has significantly enhanced its system component Asset Monitor Portfolio which facilitates the deployment of Plant Asset Management solutions. The Asset Optimizer (the module which was developed for the 800xA automation system) is a standardized processing platform for information which is generated by a wide rage of asset monitors. The examples below show how interaction between state-of-the-art technology and asset monitors can be used to rationalize traditional work flows.

Statistics collected by a number of users show that the cost of maintaining instrumentation in the chemical and petrochemical industry is high compared to other assets such as heat exchangers, pumps, compressors, valves and pipes. Differential pressure (DB) transmitters are among the most commonly used instruments in the process industry. These devices monitor pressure loss at various points of a process line as the media flows through a diaphragm in order to measure the flow rate. Particularly the instrumentation which is used in the oil industry is often susceptible to one particular problem which causes a significant percentage of maintenance costs. Impulse lines are often used to connect the pressure sensing points in front of and behind the membrane to the transmitter. However, flocculation often causes blockages in these lines, and the reading “freezes” rather than falling off to zero. It may take a long time for the operator to notice that a fault has occurred. Today, a considerable amount of effort has to be invested in regular checks to prevent the occurrence of undetected plugged impulse lines.

ABB says that the development of new diagnostic functions can help alleviate the situation. The company now offers DB transmitters which offer plugged impulse line detection functionality. These leading-edge transmitters automatically detect whether one of the impulse lines is blocked, and if so which one is affected. The gauge displays the fault on its local display.
SMS messaging
This is where integration of the transmitter and its diagnostic functionality into the 800xA automation system comes into play. Normally, a maintenance technician would have to go out and check each transmitter on a regular basis. Once the transmitters are integrated into the 800xA, the signals from every transmitter can be monitored at a central location, and corrective action can be initiated right away. A message can be sent via the field bus to flag a plugged impulse line, and this information is then automatically forwarded to the Maintenance Workplace. The responsible maintenance technician receives an SMS message, and the Asset Monitor gives him detailed information about the problem along with a specific recommendation of what action to take. “An analysis conducted by one of our customers in the oil industry revealed that a significant percentage of the cost of maintaining pressure gauges was incurred as a result of plugged impulse lines,” explained Hans-Jürgen Weidemann from the ABB Research Center in Ladenburg/Germany.
Other potential savings
According to Weidenhammer, ABB Asset Optimization minimized the time it takes to detect a problem, and it triggers a maintenance call only when necessary. Today, a substantial amount of effort is invested in routine checks which are necessary to detect plugged impulse lines as early as possible. State-of-the-art pressure transmitters and integration into the 800xA can reduce the cost to a fraction of the current level. The 800xA can also reduce cost in many other areas. The system can provide a fast, elegant preventive maintenance management solution, because the Asset Optimization System can be linked directly to the maintenance system (e.g. SAP/PM). Work orders can be entered automatically. An Automation and Asset Management Demonstrator at the ABB Research Center in Ladenburg shows how a portable calibrator can be used to calibrate a temperature transmitter and how oscillation in a control loop can be detected and repaired. For the calibration job, a calibration request in the system triggers a maintenance work order which is carried out using a hand-held device. All of the necessary data is downloaded to the device from the system, so that the technician has all of the information that he needs. Once calibration is complete, the data is sent back to the system via a client computer for storage on the system. The case of the misadjusted control loop demonstrates how components which do not have built-in intelligence (e.g. state-of-the-art transmitters) can be included in the Asset Optimization framework. A control loop asset monitor checks for oscillation caused by misadjustment. The monitor can properly diagnose the problem and send a report to the person or group which is responsible for maintenance. Corrective action can then be initiated as described above.