Any failure of any single component in a hydraulic system can lead to loss of productivity and potentially present a threat to the safety of workers, the public and the environment. A preventive maintenance program that is in place to keep all of those components in service can help mitigate those risks.
This article will discuss the benefits of installing a preventive maintenance program for one system component in particular—high-performance valves used in extreme or harsh conditions.
Differing perspectives on maintenance
Different organizations tend to look at the maintenance of their systems through a varied set of perspectives, depending on their product, process and organizational goals. Typically, there is a direct correlation between the product being manufactured and how maintenance within the organization is perceived. A company that uses a hydraulic system to produce high-dollar goods will generally be more proactive in its philosophy than a company that produces low-value commodity goods.
But, there is plenty of evidence to suggest that the low-value commodity producers could benefit from embracing a more proactive maintenance mindset. Let’s first take a more in-depth look at the range of existing approaches when it comes to maintaining hydraulic system valves:
The first approach is "run-to-failure" or reactive maintenance. For hydraulic systems, the benefit of this mindset is not having to spend any money on maintaining a valve until it fails. The downside of this philosophy is having to spend a great deal of money when the valve fails, most likely at a time that is tremendously inconvenient. When it does fail, production is shut down until the valve can be repaired or replaced, which usually happens on overtime. Lost production has to be made up, which usually also happens on overtime. This is the most expensive method of maintaining a hydraulic valve.
The second approach is to implement a preventive maintenance (PM) program. This method establishes time or condition intervals for performing a set list of tasks that are expected to prevent a piece of equipment from failing, and is designed to reduce maintenance costs, increase productivity, and enhance safety.
For example, an OEM valve manufacturer typically will establish guidelines for replacement or inspection of certain components, such as seals, gaskets and packing. The established interval at which service should occur for these components might be every two years (time) or 5,000 cycles (condition), whichever comes first. Some degree of flexibility is allowed for the end user to dictate when the valve will be taken out of service, as opposed to the roulette wheel approach of run to failure. Industry data shows that performing maintenance on a scheduled basis is three to five times less expensive than the same repair being made on a reactive basis.
The third approach – predictive maintenance – may be relatively new to many plant maintenance teams. Predictive maintenance utilizes a flow of information from a hydraulic system to help determine when maintenance procedures should be performed. Sensors that monitor pressure, velocity, vibration, acoustics and temperature are incorporated into the hydraulic system to gain real-time data about how a valve’s components are functioning. If a valve is operating at its design condition, it is left alone. When the performance data that is supplied by the sensors suggests a trend away from the design condition, then a work order is generated to perform a corrective action. While more costly initially than a preventive maintenance program, predictive maintenance eliminates unnecessary scheduled maintenance and its associated work interruptions.
Making the move from reactive to proactive maintenance for hydraulic systems
So how does a company that is mired in a run-to-failure mindset successfully make the transition to a more proactive approach when it comes to servicing their valves?
Communication counts. For this to happen, the benefits of the PM program have to be clearly communicated to different levels of the organization. For instance, the impact on profitability will be of prime interest to the folks in the front offices. That point may be of lesser concern to the maintenance crew who might view the installation of a PM program as heaping more work on them.
But, if it is presented to the crew that a valve PM program will reduce unexpected failures where they are asked to work on a weekend or holiday to repair or replace the valve, then that might raise their eyebrows a bit. The benefits of a valve PM program need to be communicated in language that suits the audience, whether that means talking about an improved bottom line or increased job satisfaction.
The goal is to get everyone on the same page in realizing that a PM program will benefit the company as a whole.
Leverage CMMS/database tools. As PM programs have grown in popularity, so have the tools available to help administer these programs. These typically can be run within the majority of Computerized Maintenance Management Software (CMMS) packages that are widely used. The foundation of these programs is the equipment database, which is the key component for establishing any PM program.
To create a database that can be used as the basis for a valve PM program, the first step is identifying and assigning a label for each valve in the system. Then, every valve needs to be logged into a database management program, whether that is a complex CMMS program or a self-made spreadsheet. Important information to be included is the valve type, date of installation, manufacturer, location and function.