Plant Maintenance

Plant maintenance is the service and repair of assets and equipment. During normal operation, assets may accumulate wear-and-tear that needs to be addressed. Deviations outside of normal operation of cause the majority of damage to equipment and assets.

Plant maintenance includes scheduled and unscheduled maintenance. Plant maintenance may be scheduled according to age of equipment or usage of equipment. Unscheduled plant maintenance can occur after equipment failure or operation excursions.

Plant maintenance can cause downtime due to process disruption and critical assets being taken offline for servicing. During plant maintenance, input supply chains may lose efficiency as assets are unable to process at their normal rate. The short-term reduction in profitability caused by process disruption, as well as the costs associated with servicing or repairs, often leads many companies to defer plant maintenance.

Increasing asset efficiency

Wear-and-tear and fouling can decrease energy efficiency directly or force components to operate outside their most efficient ranges. A poorly maintained asset may substantially deviate from the operation design, leading to difficulties in process control.

While well-maintained assets do perform more efficiently during operation, disruptions caused by frequent plant maintenance can lead to throughput reduction. In fact, production losses during plant maintenance can exceed the cost of repairing and replacing assets by 5-10 times, so keeping downtime to a minimum is critical to the profitability of a plant.

Inefficient maintenance models

The most basic plant maintenance regimen is run-to-failure, under which equipment and assets are operated until they fail. Maintenance and servicing only occur when conditions have disrupted the operation of the asset. This can be the riskiest strategy for plant maintenance, as the downtime is always unplanned. It is also the most expensive. If the equipment needed to repair or replace the components that have failed is unavailable at the time of failure, expensive delays may occur as these assets are sourced and brought online.

Calendar or cycle-based maintenance schedules are a type of planned plant maintenance. These models are an improvement over run-to-failure practices but rely on equipment manufacturers’ general recommendations and may not reflect real-world requirements. They are also blind to variations in inputs; for instance, a small change in water chemistry could accelerate or slow the corrosion of equipment.

Using prescriptive analytics to accurately and regularly schedule plant maintenance can reduce the costs associated with these inefficient maintenance practices. In particular, being able to respond to anomalous processes with ample lead time can reduce unnecessary planned downtime caused by calendar or cycle-based maintenance schedules.

Calculating the right maintenance interval

A more proactive approach schedules plant maintenance based on calendar intervals or equipment uptime. An equipment manufacturer’s guidelines, as well as your plant staff’s experience and schedules, will determine the correct interval for plant maintenance.

Efficient shift scheduling should include plant maintenance and take into account that the skills required to perform plant maintenance are different than the skills required during day-to-day plant operations. Overall, this proactive approach has the advantage of catching problems during planned downtime.

However, variation in inputs, as well as environmental conditions, can cause the intervals to be too long or too short. Longer-than-optimal intervals can lead to equipment failures, and shorter-than-optimal intervals can lead to unnecessary productivity loss. Using prescriptive analytics and predictive maintenance tools will help rectify this inconsistency.

Using predictive maintenance to improve efficiency

Predictive maintenance uses sensor data to predict when to schedule plant maintenance. Comparing current sensor data against historical data can point toward conditions that lead to unplanned downtime. Traditionally, this data has been integrated by human operators who use rules-of-thumb and intuition to link sensor data to required plant maintenance. Plant operations staff may lack the time and attention needed to detect signs that plant maintenance is required, leading to over- or under-prescribed plant maintenance.

More recently, machine learning and artificial intelligence (AI) have been applied to the problem of plant maintenance. By comparing historical sensor data with asset failure, asset optimization software can detect failure signatures long before human operators would notice anything outside of normal operation. The Aspen Mtell^® software can notify plant operators months prior to the failure of a valve, seal, heat exchanger or other piece of equipment.

Being able to intelligently schedule downtime gives plant operators more control over plant maintenance. Multiple pieces of equipment can be serviced simultaneously, and supply chain logistics can be adjusted to reduced asset throughput.

FAQs

What is plant maintenance?
Plant maintenance is the repair of equipment, replacement of equipment components and replenishing of non-throughput consumables of an asset. Normal wear-and-tear and operation excursions cause assets to require plant maintenance.

What is plant service and maintenance?
Plant service and maintenance is an activity that seeks to extend the life of an asset through inspection, sensing, repair and replacement of components.

What are the objectives of plant maintenance?
The objectives of plant maintenance include extending the life of equipment, as well as increasing efficiency by reducing waste caused by wear-and-tear, fouling, leaking or other consequences of operation. Plant maintenance aims to prevent unplanned downtime caused by equipment failure.

Why do we need plant maintenance?
Plant maintenance increases the health and safety of employees by reducing the risk of workplace accidents. Plant maintenance helps companies achieve asset optimization by reducing unplanned downtime. Plant maintenance also helps assets perform closer to their designed efficiency, decreasing costs associated with suboptimal equipment performance as well as increasing reliability of control.

Why is plant maintenance important?
Plant maintenance helps to reduce forced downtime by turning unplanned downtime into planned downtime. Plant maintenance needs to be accounted for in the scheduling and control of a plant, as taking assets offline for plant maintenance can disrupt the throughput of a plant.

What is equipment maintenance management?
Equipment maintenance management is any system used to keep equipment in a serviceable condition. In addition to the physical process of inspecting, servicing and repairing equipment and assets, equipment maintenance management also includes operational decisions about when, how and under what conditions equipment should be serviced.