By accessing the flow meter's diagnostics, we quickly recognized the problem, which was corrected by backflushing sensor tubes to clear partial blockage and bring all diagnostic indications back into normal range. The process engineers and production personnel became "believers" after this type of alert was repeated several times on various mass flow meters within the process.
Spreading The News
To gain plant-wide support for the predictive maintenance technology, we needed to inform site supervision and management personnel about what was happening in our unit. So we began issuing single-sheet "GT Success Stories" describing how diagnostic alerts had prevented costly production impacts and shutdowns. The news soon began spreading to other areas of the plant.
As more successes followed, "reliability" became more of an expectation than an aspiration. It took on considerably greater importance with the establishment of a dedicated Reliability Group for the entire site (see sidebar). At present, two electrical technicians focus on using predictive technology to continue improving overall electrical reliability. For example, in preparation for a recent scheduled outage at the GT Unit for catalyst replacement, they conducted diagnostic scans on about 40 Type A critical control valves using the AMS ValveLink Snap-On application as a proactive means of determining which valves should be serviced. This marked the first time 100% of the unit's Type A critical control valves were evaluated prior to an outage. It caught some previously unrecognized deficiencies, resulting in SAP work order entries to replace seats, rings, packing and even digital control valve positioners to maintain those valves in top operating condition.
In the past we routinely pulled many valves for overhaul — often unnecessarily — based solely on the amount of time they'd been in service. By completing preliminary scans and tests, reliability technicians determined which assets really needed maintenance and excluded ones that didn't, saving a substantial amount of time and money during the outage and ensuring the plant could be restarted without delay. With maintenance headcount at a premium, it's crucial to allocate man-hours wisely to complete all the highest priority shutdown activities.
We test, plan and schedule accordingly to avoid reactive situations where plant personnel must "drop everything to put out the fire." Every avoided reactive maintenance "fire" is a success to me and the rest of our organization.
Expanding the Program
Plant management wants the site to strive to become a world-class maintenance facility; establishing a reliability program based on asset prioritization was a major step in that direction. The recently formed Reliability Group now works closely with the Production and Maintenance Departments toward common plant goals and key performance indicators.
We currently are deploying AMS Device Manager software across the entire site. Soon 70% of the plant, encompassing approximately 1,200 I/O points, will be covered online. In the process, we're replacing many older field devices assessed as being critical with smart instrumentation, giving our asset management system more points to monitor for potential equipment failures.
Our ultimate goal is to prevent any unexpected outages due to instrumentation and equipment failures by continually enhancing manufacturing reliability. To date AMS Device Manager alerts have prompted generation of more than 100 deficiency work orders annually. This doesn't take into account the numerous auto-generated PM route work orders that make use of AMS Suite applications.
Joel Holmes is site tactical reliability engineer for Monsanto, Muscatine, Iowa. E-mail him at email@example.com.