Take Manual Out Of Maintenance

High-precision processes, such as those used in pharmaceutical manufacturing, benefit greatly from the ability of smart instrumentation to minimize downtime.

Smart instrumentation, with diagnostics and verification capabilities, advances uptime and safety in process systems.

By Bethany Silva, Endress+Hauser

In the process industries, maintenance is necessary to preserve equipment health, maintain operational safety, and ensure product quality. Until recently, most maintenance was performed manually because there were limited options. This type of work takes considerable time and effort, and often requires stopping the process, resulting in a potential loss of productivity. It also introduces the risk of human error while configuring instruments and can pose a safety risk to technicians when working in areas that are hazardous or difficult to access.

Today, technological advancements in instrumentation and other plant tools are automating regular maintenance. Smart instruments achieve this with a wealth of diagnostic data, along with on-demand and automatic online verification procedures, alleviating the need to disrupt the process for measurement optimization. This reduces the risk of human error, improves personnel safety, and keeps plant downtime to a minimum, all while preserving the standards of quality that maintenance aims to uphold.

Figure 1: Left unmaintained, plant performance can degrade over time due to accumulating process conditions and measurement drift. Courtesy Endress+Hauser

Manual maintenance drawbacks

Every plant process has critical measurement points that must be accurate to ensure proper functionality. However, instruments used to make these measurements can drift or detrimental process conditions can develop, such as corrosion or debris buildup (Fig. 1), reducing accuracy over time.

Preventive maintenance preserves safety and quality by ensuring accurate measurements and correct equipment functionality. Still, it can be expensive, inefficient, and can even pose a degree of risk. This is especially true when it must be performed manually and particularly when instrument removal is required.

In these cases, plant personnel must often disassemble equipment, remove instruments, place them on a test bench, calibrate and make necessary configuration adjustments, and reinstall them. This can be very difficult in compact, elevated, or hazardous areas. Additionally, every reinstallation introduces a risk of errors or contamination, particularly concerning in the hygienic industries.

Each removal often requires at least a partial process shutdown. For continuous processes, a pause may be required during maintenance. Although batch processes present a window for maintenance between batches, the time required often causes delays, affecting operations throughout the supply chain. Even the briefest downtime can be costly for facilities striving to maximize uptime.

Automated diagnostics

Smart instrumentation addresses these and other issues with automated verification, by which an instrument conducts a series of diagnostic tests to ensure its internal mechanical, electronic, and electromechanical components align with factory calibration. 

This type of verification does not provide the same level of assurance as bench calibration to a known standard, but it confirms the correct operation of critical components and can draw attention to potential issues before instrument or process failure occurs. Automated verification takes only a few seconds in each instance and can generate a verification report upon completion, certifying the instrument is suitable for use.

Automated verification can serve as an alternative to traditional preventive-maintenance checks while providing numerous advantages. First, it alleviates the need to remove and reinstall instruments, reducing labor requirements and increasing safety. Second, it diminishes the need to pause the process, minimizing plant downtime and increasing productivity. Third, the resulting verification reports can provide plants with the basis to move from preventive- to predictive-maintenance strategies, reducing manual intervention to only areas that require attention to keep operations on track.

In addition to on-demand verification reports, smart instrumentation can produce automated diagnostic notifications when sensing issues or anomalies at any point in time. This informs operators of developing issues, empowering them to take corrective measures to prevent larger problems from forming down the road. Diagnostic messages can also include specific directions that suggest potential root causes or clarify required mitigative action.

Figure 2: Two instruments, A and B, are operated for 40 months. Instrument A must be manually calibrated every six months to limit risk to acceptable levels. Instrument B performs automated verification every two months, so risk increases more slowly. Manual calibration must be performed only once every 30 months to remain within acceptable levels. Courtesy Endress+Hauser

Without automated diagnostics, minor errors can go undetected, resulting in quality and safety reductions (Fig. 2). The predictive-maintenance monitoring techniques described above make it possible to identify issues sooner, more reliably, and at lower cost, than with manual inspections.

By leveraging automated verification and diagnostics, plant personnel can significantly increase manual maintenance intervals while benefitting from greater productivity and safety, with a lower risk of undetected instrumentation or process issues.

Transmitter verification

Verifying pressure transmitters typically requires manual access to the instrument. Technicians must then open transmitter housing covers and search for the correct terminals in the control cabinet, tasks that are time-consuming and prone to error. Depending on the instrument location, hot work permits may be required and, in some cases, scaffolding or other access equipment is needed. Smart pressure transmitters eliminate these issues by facilitating automated and remote verification.

Using a mobile device, operators can connect using Bluetooth from a maximum distance of 50 ft. and perform a device verification in about three minutes without touching any wire terminals or taking the instrument offline. This procedure checks the most important components, providing more than 95% test coverage.

When verification concludes, the device generates a report containing an overall pass/fail result and additional information, including terminal voltage and sensor temperature. These reports are stored directly on the instrument for accessibility and can be exported as PDFs to prove regulatory compliance.

Cerabar pressure transmitters use Endress+Hauser’s Heartbeat Technology to perform automated verification and generate reports. Courtesy Endress+Hauser

Case histories

An Endress+Hauser Promag electromagnetic flowmeter in a chemical manufacturing plant periodically reported zero flow, triggering a safety shutdown, and bringing production to a halt. Standard fault analysis failed to reveal the cause, but an automated verification, using the flowmeter’s embedded technology, revealed the empty pipe detector cable was faulty, providing a clear direction for further analysis and resolution.

A pharmaceutical supplier designed a new plant with smart technology to improve efficiency. In its prior facility, it used standard temperature sensors in steam-in-place (SIP) processes. Those sensors required calibration every six to twelve months, creating significant downtime.

For the new plant, the supplier selected self-calibrating iTHERM TrustSens sensors to eliminate these costly procedures and improve measurement accuracy. These pharmaceutical-grade temperature sensors incorporate a high-precision reference that experiences an abrupt ferromagnetic change at its Curie point. This change in properties can be detected electronically by the instrument’s transmitter, triggering an automated process value checkpoint upon reaching the Curie point.

To assess accuracy of the new sensors, the supplier put them through four months of validation in an SIP process at 118 C. The sensors reliably performed self-calibration each time the Curie point was reached, deviating just 0.03 C on average over the whole duration, i.e., a tenth of the maximum permitted error of a standard Pt100 class AA sensor. The supplier now has the added benefit of a full calibration and report after every SIP cycle without any required manual effort.

Enhance

When the pressure to optimize productivity is felt, it can be easy for plant personnel to de-emphasize safety and quality. But smart instrumentation advancements significantly ease their day-to-day job, helping facilities transition from exhausting preventive-maintenance exercises to reliable predictive-maintenance techniques.

These advancements help plant personnel uphold safety and quality standards while reducing the need to disrupt critical processes with manual maintenance. Additionally, smart instrumentation, with automated diagnostics and verification, decreases error risks and provides staff with more time to optimize and innovate. EP

Bethany Silva is the Life Science Industry Manager for Endress+Hauser, Greenwood, IN (us.endress.com), a global process and laboratory instrumentation and automation supplier. Silva is responsible for the strategic direction, vision, and growth of the U.S. Life Science unit. She has more than 20 years of process-industry experience, holding positions in R&D, process development, marketing, and technical sales.