Emerson’s Lifecycle Services Business Development Manager John Carlow recently published an article in the March/April 2022 edition of Process Instrumentation. The article is titled Get Expert Operating Analysis with Remote Valve Condition Monitoring. It describes how plants can unleash the power of their installed equipment to avoid unplanned outages by utilizing remote monitoring services. A summary of the article follows.
Automated valves are critical to most processes, and their unanticipated failure costs plants millions of dollars in production every year. Avoiding such losses is achievable if the plant can detect valve performance degradation before it transitions to outright failure (Figure 1). While many sites have taken the first steps to achieving this goal, few are entirely successful, as John explains:
Many users have already installed digital positioners with advanced sensors and diagnostics on their valves to detect potential problems well before outright failure. Unfortunately, only a very small fraction of plants utilize this capability to its full extent, and many plants barely use diagnostic capabilities at all.
There is a myriad of reasons why plants fall short. Some positioner diagnostics only run when the valve is offline, limiting the opportunity for testing. Other plants have positioners with online diagnostic capability but simply lack the time and resources to take advantage of the data provided by these devices.
Remote valve monitoring closes the gap
When the plant personnel are overwhelmed, remote valve monitoring provided as a third-party service can be an excellent solution. Valve condition monitoring takes advantage of the digital positioner diagnostics already installed in many plants, which continually sense valve travel, drive signal, temperature, cycle count, travel deviation, supply air pressure, friction/torque, valve stroke time, and other parameters.
Using Fisher ValveLink software to perform scheduled online testing of each valve as it operates allows data to be automatically gathered any time the positioner detects an abnormal condition. This data is then transferred via various methods dependent upon the specific requirements of the company’s IT staff. Data files can be emailed every week, automatically transferred via a wireless network and a data diode (Figure 2), or transmitted via a secure data highway and firewall set up by the users’ IT department.
Once the data is delivered, John describes the next phase of the process:
Emerson experts, serving as an extension of onsite staff, review and analyze the diagnostics information via a cloud-based analytics platform. The analysts, who are factory trained and certified, look at the current data and monitor historical data trends to identify performance degradation or developing mechanical problems.
The result of this analysis is delivered to operations and maintenance plant personnel via a combination of manual monitoring and automated functions. A partial list of the items typically highlighted in the reports include:
- Air supply or filter regulator problems
- Actuator or diaphragm leaks
- Packing issues
- Valve oscillation
- Inability to reach or maintain setpoint
Non-critical issues are noted in a monthly report documenting the overall health of each valve, with recommended corrective action provided as needed. Critical issues are highlighted immediately, allowing the plant to act before a failure occurs.
Remote monitoring can translate into dramatic savings for pressure swing adsorption units or heat recovery steam generators (production units. In both cases, the units are dependent upon automated valves operating in very punishing conditions. Remote monitoring allows developing valve issues to be flagged early to avoid unplanned outages, improve uptime, and increase production.
A less obvious benefit of valve condition monitoring is its ability to aid in turnaround planning. John describes this scenario:
A combined cycle power plant was overhauling every critical valve during each outage to maximize uptime upon restart. After installing upgraded digital valve positioners and implementing diagnostic alert software, plant personnel were able to focus their repair efforts more efficiently, saving $68,000 in one shutdown alone.
Predicting the future is no simple feat, but advanced diagnostics in digital positioners can allow maintenance staff to do exactly that. When a plant lacks the resources to implement internal monitoring, the work can be outsourced to knowledgeable third-party experts who can detect problems before they become major issues to improve a plant’s bottom line significantly.
Visit the Valves, Actuators & Regulators Lifecycle Services section on Emerson.com for more on ways to better manage equipment repair, turnaround support, and field services.