There are several different types of maintenance, each designed to address specific failure modes. By matching the right type of maintenance with the failure mode that you are dealing with, you can prevent equipment failures, prolong equipment lifespan, minimize costs, improve safety, and reduce downtime. In this article, we will delve into the specifics of each type of maintenance in further detail.
Maintenance can be broadly categorized into two types: Preventive Maintenance and Corrective Maintenance.
Preventive Maintenance is performed before any equipment failure occurs, and includes Time-Based Maintenance, Failure Finding Maintenance, Risk-Based Maintenance, Condition-Based Maintenance, and Predictive Maintenance.
On the other hand, Corrective Maintenance is carried out after a failure has occurred and can be further classified as Deferred Corrective Maintenance or Emergency Maintenance.
Preventive Maintenance (PM)
Preventive maintenance is a maintenance strategy that focuses on performing regular replacement or restoration of equipment, regardless of its current condition. This can include scheduled tasks such as replacement or restoration and is intended to prevent equipment failure.
Risk-Based Maintenance (RBM)
Risk-Based Maintenance (RBM) is a strategy that prioritizes the allocation of maintenance resources to equipment that poses the highest risk of failure. Equipment that poses a higher risk and has severe consequences of failure will be subject to more frequent maintenance and inspections, while low-risk equipment may require less frequent maintenance.
This approach continuously optimizes the frequency and scope of maintenance activities based on testing and a risk assessment methodology that considers the likelihood and consequences of failure.
Failure Finding Maintenance (FFM)
Failure Finding Maintenance is a type of maintenance that is focused on identifying potential failures in protective equipment such as pressure safety valves and trip transmitters.
This type of equipment is not typically used during normal operation, so hidden failures may go unnoticed. These hidden failure modes must be found before they can be relied on to protect the equipment.
Failure Finding Maintenance does not prevent failure, but rather detects it, and once detected, the failure must be repaired. This type of maintenance is typically performed at fixed intervals, based on regulations or risk-based assessments.
Time-Based Maintenance (TBM)
Time-Based Maintenance (TBM) is a type of maintenance that is performed at regular intervals while the equipment is still in operation, with the goal of preventing failure or minimizing the risk of failure. Preventive maintenance can be scheduled based on time, such as every week, month, or quarter. It can also be based on usage, such as every 150 cycles, 10,000 hours, or 10,000 kilometers for a car.
Condition Based Maintenance (CBM)
Condition Based Maintenance (CBM) is a maintenance strategy that focuses on identifying physical evidence of an impending failure in equipment. Unlike time-based maintenance, CBM does not rely on the age of the equipment to determine when maintenance is needed. Instead, it looks for warning signs that a failure is about to occur, in order to take action to prevent it or minimize its consequences.
It is important to note that CBM does not reduce the likelihood of failure, but rather aims to intervene before the failure occurs, with the goal of being more economical and less disruptive to equipment availability.
Predictive Maintenance (PDM)
Predictive Maintenance (PDM) is an advanced approach to Condition Based Maintenance (CBM), that uses multiple process parameters from online sensors to predict when equipment is moving away from stable operating conditions and heading towards failure.
The goal is to predict when the failure will occur, and schedule maintenance intervention at the appropriate time. With the advent of Artificial Intelligence, machine learning, and low-cost equipment sensors, PDM is becoming a fast-moving and exciting field in the Maintenance and Reliability industry.
However, it is important to note that even the most advanced PDM approaches should be based on sound reliability principles, and the use of PDM has been overhyped in many cases, often being little more than CBM rebranded with a new buzzword.
Corrective Maintenance (CM)
Corrective Maintenance (CM), also known as run-to-failure, is a maintenance strategy that only restores the function of equipment after it has failed. It assumes that the failure is acceptable and that preventing failure is not economically or technically feasible.
This strategy is often used in situations where the consequences of failure are minimal and do not require immediate repair. However, it can also be the result of unplanned failures that were not prevented through preventive maintenance.
When discussing the types of corrective maintenance, it is important to distinguish between Deferred Corrective Maintenance and Emergency Maintenance.
Emergency Maintenance is a type of corrective maintenance that is so urgent that it interrupts your plans and schedules and can lead to disarray. While some people may thrive in this environment, it is not an effective approach for achieving reliability.
Emergency Maintenance is costly, dangerous, leads to longer equipment outages, and has a greater impact on production. That’s why world-class organizations aim to keep Emergency Maintenance at less than 2% of their total maintenance.
In summary, there are different types of maintenance such as preventive and corrective maintenance, that are designed to address specific failure modes of equipment. By matching the appropriate type of maintenance with the failure mode, you can create highly efficient preventive maintenance programs that prevent equipment failures, prolong equipment lifespan, minimize costs, improve safety, and reduce downtime.
It’s important to understand the different types of maintenance and how they can be used to keep equipment and systems running smoothly. Preventive maintenance is a proactive approach that aims to prevent failure before it occurs, while corrective maintenance is reactive and repairs equipment after it has failed. If you want to learn more about the different types of maintenance in greater detail, then you can check out this article on the types of maintenance.