Comprehensive valve monitoring for improved valve management — Modern control valves are able to capture and store a bunch of operational data. So it is possible to monitor and elaborate available information around those assets to predict failures. Appropriate counter measures prevent plant shutdowns, which positively influences production efficiency. Additionally, plant managers are able to schedule necessary maintenance and to minimize wear, thus significantly reducing the cost of operation — another key issue for profitable operation. As a repetitive process the analysis and calculations during operation enable valuable improvements.
Control valves are commonly used actuators in process industry plants. They are important for the operation and safety as unexpected valve failures may lead to plant downtimes, process upsets and risks for people and environment. Timely maintenance of these plant assets is essential to ensure high plant availability and process safety. On the other hand, servicing healthy assets based on fixed time schedules introduce unnecessary costs.
Typically, valves are driven pneumatically and combined with an electro pneumatic positioner that adjusts the valve actuator’s position based on a control signal. But most valves are never monitored or optimized in respect to their positioner settings. There is room for improvements in case of valve management that finally translates into measurable monetary success:
- Detecting blockages, accumulated dirt/pollution, wear and leakages that result in an increased energy demand when operating plants/equipment;
- acquiring and optimizing operating conditions at equipment and actuators to increase the energy efficiency of drives and supply energies;
- introducing solutions to prevent or reduce non-scheduled process states that in turn result in an increase in the production and energy efficiency.
Valve Data Driven Service Scheduling
“In many production plants today there is only scheduled maintenance implemented for valves. And indeed, many maintenance procedures are implemented too early or too late, which is the reason for inefficient production processes because of bad conditions,” explains Dörte Sack, head of the Technology, Concepts and Digitalization group within Siemens Process Industries and Drives, the situation today. “And there is a strong need to centralize and consolidate supplier knowledge with user experience in a central system. It significantly eases the intensive use of relevant information for maintenance purposes”.
Intelligent valve positioners like Siemens Sipart PS2 collect and maintain a bunch of serviceable information that allows advanced maintenance planning. Consequentially a data driven service scheduling based on performance data significantly help to reduce maintenance efforts. As digital technologies reshape the capability to progressively capture and consolidate asset data, it is a matter of course to apply applications which deliver a comprehensive overview about installed valves in the plant.
By expanding its integral portfolio of hardware, software and services, Siemens is driving forward the digitalization of industrial automation.
The Siemens Valve Monitoring Application serves customers with significant advantages while extending the transparency on valve and positioner quality. Besides presenting the general view on all valves, it recognizes anomalies and wear and tear in time through monitoring of suitable key performance indicators (KPIs).
This allows assigning the dedicated valve to a planned maintenance slot. In-time maintenance is a key enabler for cost-optimized use of the installed assets, as work procedures are scheduled not too early and not too late.
How Monitoring Ensures Advanced Scheduling based on KPIs
The app takes advantage of wealth data, which are collected by the positioners as for example total travel of valve, number of direction changes, slip-stick, pneumatic leakage and more. This forms the base to recognize e.g.
- questionable positioner settings like not activated diagnostics, implausible limits, no tight-closing and more;
- abnormal movement data and/or abrupt changes in valve behavior;
- badly designed valves (always open, always nearly closed, …).
The consolidated information enables to extrapolate trends regarding the wear limit, thus determining the expected maintenance date based on real-time information. Operators and maintenance managers receive deep insights of the valves and may reschedule and rearrange maintenance activities.
Work procedures can be assigned to maintenance slots based on the devices predictive maintenance dates minus a safety reserve, which positively influence the cost of ownership. The recommendation is updated whenever new valve data are supplied, resulting changes in predictions are shown, automatic and manual re-assignment of valves to maintenance slots is possible.
Valve Managemnet Takes Advantage of Versatile Information
As an application developed for the Process and Asset Performance Suite of Siemens the software marks a milestone for digitalization in process industries. Customers benefit from the overview about installed valves in the plant. The App takes advantage of available but rarely used information in valve positioners. It extends the transparency on valve and positioner quality and recognizes anomalies and wear in time for planned maintenance slots through monitoring of suitable KPIs.
Accomplishing smart data-driven predictive instead of corrective maintenance with clear guidance for maintenance engineer/asset manager reduces operational expenditures for the plant, that pave the way for to increase a companies’ bottom-line margin.
* * The authors are Manager Chemical Industry Technology & Concept, Siemens, Karlsruhe/Germany.