According to Tesfay Tesfamicael, a consultant with MaxGrip Americas, before any plant is able to maintain an asset, some basic fundamentals must be met: First is understanding the asset's function and its associated performance standards, followed by ensuring the asset performs that desired function.
"Function is the purpose for which an asset is designed," Tesfamicael explained, adding that an asset can have two functions.
"The primary function relates to speed, feed rate, load quantity, tank capacity and product quality," he said in an address discussing maintenance strategy at the Society for Maintenance & Reliability Professionals (SMRP) Houston Chapter 2nd Quarter Meeting held recently in Deer Park, Texas.
The secondary function, he explained, relates to safety and environmental protection, operation protection, cost efficiency, energy consumption, integrity of the structure, comfort and appearance.
"Reviewing existing asset information helps in determining what we actually know about our system, such as flow diagrams, piping and instrument diagrams, process procedures and base of design packages," he said. "Identifying gaps and how to close them gives your first phase of criticality analysis based on operational impact, age, historical impacts and future projects."
The advantage of the criticality ranking is knowing where preventative maintenance (PM) needs to be focused.
"Maximize resources based on priority and execute work in a cost-effective manner," he said. "That's the reason it's important: because we don't have unlimited resources. Where's the biggest bang for our buck? What are the assets we need to utilize these resources to make sure we get more reliability and availability in whatever metrics we're using?"
Tesfamicael said determining criticality also helps with choosing an appropriate maintenance strategy.
Why RCM?
Reliability-centered maintenance (RCM) is a risk-based process for determining cost-effective maintenance and surveillance actions to maintain a proven level of reliability.
"The main difference between it and general PM is that we look at it from an operating context," Tesfamicael said. "We don't just say, 'I want this thing to pump' or 'I want this thing to heat up.' We specifically look at the operating context: What level is appropriate? What temperature is appropriate? What flow rate is appropriate? And if we're outside of those, what are the mitigating factors?"
Tesfamicael warned that "applying RCM to everything" is not necessarily among the most cost-effective strategies.
"You need to have facilitators and people who are actually knowledgeable about the work processes who might not already be in your organization," he said.
Reliability analysis, Tesfamicael noted, is an evolving system, with innovation in asset management being directly related to rising expectations. During the 1940s and 1950s, a plant's maintenance strategy was to fix something if it was broken. As the number of plants grew in the 1960s and 1970s, components had longer lifespans, resulting in lower costs. The 1980s through the 2000s have brought even more plants and reliability, as well as greater safety, better component quality and longer life expectancy, increased cost efficiency and improved environmental impact.
"Expectations, understanding and our tolerances toward injury and safety change," Tesfamicael said. "So much has changed that now we need these processes to help us make decisions."
As plants consider which maintenance strategy best suits their needs, "whether risk-based inspection or RCM, sticking to one strategy is also very important, as opposed to trying 50 different work processes," he concluded. "Sticking to one and following it through is key."
