Unlock hidden value: Adding fixed equipment to plantwide condition monitoring ecosystem

Over the years, we’ve built an enviable reputation in the industry as experts on rotating and reciprocating machinery. We’re very proud of that reputation and we work actively every day to continue earning and retaining that trust. It’s not surprising, therefore, that when people think of System 1™, they think of it as a platform for managing such assets. 

However, System 1™ can be used to managed fixed assets—not just rotating / reciprocating assets.  What’s more, customers are starting to tap into the full power of Cordant™ Asset Health, built on System 1™, to manage a much broader cross-section of assets. As one of our customers put it, “even if it doesn’t go round-and-round or back-and-forth, I can use Cordant™ Asset Health to help me manage it.”

Why the spending gap for inspection and maintenance?

In many plants, the inspection and maintenance (I&M) spend devoted to fixed assets is considerably greater than that for rotating/reciprocating assets[1].  One of the primary reasons is that rotating and reciprocating (R&R) machinery is more heavily instrumented than fixed assets, and the sensors on R&R assets can accurately detect such a broad range of mechanical problems based on vibration and position measurements.  Thus, condition-based maintenance based on sensor data is very practical for R&R assets because the technology is readily available and readily employed. Fixed assets, however, don’t enjoy such a suite of sensors.  As such, it is common for companies to rely primarily on inspection-based approaches based on running hours and calendar intervals.  In other words, condition is assessed by visual inspection or other means that are generally invasive and require a process outage, rather than by other means.

The shortcomings of inspection-based approaches

One of the significant shortcomings of inspection-based approaches is what can be called “the assumption of uniformity”.  The assumption goes something like this: “We inspected the pipe wall thickness, and it wore X amount in Y years.  That means it will wear 3X amount in 3Y years.” This seems entirely reasonable to the casual observer, but it assumes that wear occurs at a uniform rate.  What practitioners can tell you, however, is that uniformity is only valid when nothing else significant is changing.  If the process fluid composition in that same pipe has had an “event” —even of relatively short duration—the wear and corrosion occurring in a matter of minutes or hours can eclipse that which would normally take years.  The US-based refinery mentioned in footnote 1, for example, experienced a pipe wall rupture that was completely unanticipated based on uniform wear rates.  The failure resulted in a fire and ensuing costs that surpassed $100 million USD. To make matters worse, it occurred in a heavily populated region where environmental concerns are among the highest in the country. 

The lesson from this is that uniform wear assumptions can lead to disastrous consequences. 

So, what are you to do?  If uniformity cannot be trusted as a reliable mechanism on fixed assets, and technologies to continuously monitor these assets are not as readily available (or economically feasible) as on R&R assets, what options remain?

Enter the role of process data.

Process data + Cordant™ Asset Health take management of fixed assets to next level

Fixed assets—including heat exchangers, piping, vessels, heaters, coolers, valves, and even instruments such as transmitters—all have one thing in common: the process fluid (whether gas, liquid, or solid) is moving through them, contained within them, altered because of them.  And where there is process, there are process measurements and process data.  Often, this data is retained in a process historian.  Even in instances where it is not archived in a process historian, it is often readily available from the Distributed Control System (DCS) or other process control system by means of standard protocols such as Modbus or Open Platform Communications (OPC).  By bringing this data into Cordant™ Asset Health, customers are doing some amazing things.  In fact, some customers without a process historian are using Cordant™ Asset Health as a process historian and using it to perform condition monitoring on their fixed assets. For maximum benefit, they could use it as a repository of both vibration and process data, and for proactive condition monitoring of both R&R and fixed assets.

Armed with this process data, customers can take their fixed asset programs to an entirely new level.  The measurements are frequently not “rocket science”.  Things don’t have to be complicated to be effective. For example, clogged filters can often be easily ascertained simply by looking at differential pressure across the filter element, and such measurements are usually readily available in the process control system.  Other examples can be cited for flows, temperatures, level fluctuations, fluid composition, and other readily available measurements in the process control system.  The question thus becomes not “is the data available?” but rather “is it being leveraged for condition monitoring purposes and not just used for control purposes?”

Case Histories

Consider another US-based refinery, different than the one previously mentioned.  They have been a customer for more than a decade and are actively using Cordant™ Asset Health to monitor not just R&R assets, but also fixed assets.  Here are two such examples from that facility:

#1: Naphtha Hydrotreater Feed Filter

The filter at the front end of the Naphtha Reformer has a direct effect on the quality of the final product. Bypassing this filter or choking the process by operating with a clogged filter have serious operational consequences, making the filter’s condition a critical part of the Reformer process.

A review of historic data showed that these filters are replaced every 45 to 90 days; however, 35% of the work orders initiated for filter replacements were categorized as “urgent/emergency”. Work performed under such conditions interrupts the maintenance team’s planned activities for the day, diverting resources, disrupting schedules, and adding both maintenance and operational costs. The customer saw an opportunity to monitor filter degradation and shift from “unplanned and urgent” to “planned and routine”.

Two pressure sensors on either side of the filter are fed into a rule the customer wrote themselves in the Decision Support module. The rule first subtracts the two pressure signals to create a “virtual” differential pressure signal. This differential signal is then trended and compared to empirically derived “normal” values. For example, experience had shown that 6 PSI of differential is the point at which maintenance personnel should be initially advised. This was configured as a “level 1” severity in the system, triggering a notification to maintenance planning engineers to watch the differential pressure twice a day. At 9 PSI, the severity is upgraded from 1 to 2 (which is still below the Alert level –severity level 3). Once at severity 2, another notification is sent; this time, to enter a work order for a planned filter replacement.

Should the differential reach 15 PSI, an alert, or severity level 3 alarm is sent. At this level, the work order will be upgraded to “urgent/emergency”. Finally, if the differential pressure reaches 30 PSI, a level 4 “Danger” notification is sent, instructing the operator to immediately open the bypass valve to prevent damage to the unit.

In the first two years alone since this simple—but effective— Decision Support rule was implemented, it was invoked ten times, resulting in ten planned, routine, filter replacements without a single “urgent / emergency” work order being necessary.

#2: Asphalt Heater – Decoking Plant

The asphalt heater tubes can be affected by two potential problems. Following is a summary of these potential problems and how System 1™ helps to address them. 

i. Overfiring

Overfiring results in loss of creep strength and can lead to premature tube failure. Fortunately, it is relatively easily addressed. The seven heater tube temperatures are available in Cordant™ Asset Health and a simple rule in the Decision Support module then compares tube temperatures against empirically derived maximum limits, obtained by examining historical operating and maintenance data for the tubes. Depending on the severity of the temperature violation, a level 3 or 4 alarm is generated. An inspection engineer then uses this data to assess the situation and tailor appropriate actions, such as creep strength analysis.

ii. Clogging

Clogging affects unit efficiency, and although more complex to address than overfiring, it is still straightforward to implement in the Decision Support engine. The algorithm computes the average weekly temperature of the unit and compares the present week against the previous week. Increases above certain limits are cause for concern and trigger a notification for the process engineer to review operating parameters. The engineer uses this data to analyze inlet conditions and feed compositions, determining their effect on decoking time. By triggering notifications to the process engineer at the right time, the decoking process is optimized, saving time and money.

Learn more about how customers are successfully monitoring fixed equipment with Cordant™ Asset Health in part 2.