Compressed Air Systems

3 steps to better compressed air management

Not picking up signals of imminent parts failure? Suspect you’re not getting your money’s worth on bundled services or products? Here’s how to fix that.

By Phil Beelendorf, CRL, CMRP

In this article:

When you think about utilities, the first thing that likely comes to mind is water, electricity, or steam. While managing these utilities is a critical aspect of an overall asset management strategy, the so-called fourth utility, compressed air, is often overlooked. One of the reasons for this may be is the fact that compressed air is a mystery to many of us.

While most organizations wouldn’t dream of turning over control of their electrical or steam-generating assets to a third party, many have no problem doing so with their compressors. OEMs are happy to oblige and offer turnkey packages for compressor and dryer maintenance. Operations treats compressed air like it is manna from heaven, turning compressors on and off as they would a light switch in their homes.

To ensure that adequate air supply is available, most organizations rely heavily on redundancy, and when a compressor goes down for any length of time, they turn to their OEM, who is more than happy to supply rental units. By the time most organizations rid themselves of the rentals, they have paid for the cost of a replacement unit. But it does not have to be this way.

A few years ago, we had a disastrous year with compressor/dryer reliability. Age-related failures and inattention to our assets created a perfect storm of high cost and downtime. We were swimming in a sea of rental units as we struggled to work our way out of the mess we had created. This painful experience forced us to wean ourselves off of the “one-size-fits-all” maintenance strategy our OEMs offered and gave us the incentive needed to utilize the asset management strategy we had successfully employed with many of our other asset classes. We established a road map, rolled up our sleeves, and went to work. We have not looked back.

Any good strategy starts with a plan. You have to know where you want to go and need to create a road map to get there. So, the logical first step for us to figure out where we were going was to conduct a formal audit of our compressed air maintenance, repair, and operations (MRO) practices using our site proprietary audit tool.

Formulate your goals

Once we assessed our current state, we formed a multifunctional team of stakeholders to determine what our goals and objectives would be. We came up with the following goals:

  1. Improve utilities personnel’s ownership of compressed air assets.
  2. Remove rental units from the site and reduce our future dependence on them (no rentals to be used other than for equipment and plant outages).
  3. Have at least one standby compressor available at all times.
  4. Optimize energy use by developing a master control strategy.
  5. Reduce our maintenance cost by 20% over the previous five-year average.
  6. No overall equipment effectiveness (OEE) impact assigned to compressed air failures.

Two of the first things you can do to wean yourself off OEM “one-size-fits-all” service contracts are to increase operator knowledge of how compressors function, and teach operators to recognize the warning signs of imminent failure (potential failure modes). In this way, you can use operator rounds instead of frequent OEM service-provider visits to monitor equipment health.

If you are not already doing so, have your site maintenance staff take over routine maintenance. Don’t get me wrong: I am not going to ask our craftsmen to rebuild an air end, but they are certainly capable of changing the oil and air filters. I also find that we have better maintenance expertise than our service providers for many tasks, such as air dryer valve troubleshooting and most, if not all, of the predictive maintenance (PdM) route-based activities completed on site.

If you don’t believe this is true, ask your technician the next time he or she is on site taking vibration readings to explain how to read a spectrum and see what the response is. If you take over PdM, routine maintenance, and use operator basic care (OBC) rounds and data monitoring to identify failures before they occur, you can drastically cut down on the number of visits your service providers say are necessary to maintain your compressed air system in a healthy state. 

Early on, our team recognized the need to enlist the help of our original equipment manufacturers (OEMs) if we were to change the way we managed our compressed air equipment. The major OEMs tend to have a fairly rigid model when it comes to service, and we realized we were going to have to “shake a few trees” to get them to adapt their business model to fit our strategy.

Compounding this challenge was the fact that we have two major OEM brands of equipment at our site, and no two of our compressors were alike. This meant it would be difficult to rely on one supplier to service all of our equipment. Most OEM service centers own a geographic territory, so it is difficult to develop competition among OEMs. Finally, both of our OEMs had a “value-added” services division. These divisions were run as a profit center, relying heavily on audits and selling “value-added” packages to generate revenue. Using these services can reduce TCO over time but tend to increase costs in the short term. And there was little appetite for spending additional money after the disastrous year we had just experienced.

Set provider expectations

Challenges aside, we set about the task of developing service provider expectations, and once this was done, we met with our OEM representatives to outline our intentions. We had two goals:

  1. Assess whether we believed our service providers could transition to an asset management maintenance model.
  2. Provide an incentive for them to help us accomplish some of our program goals by indicating the evaluation could potentially result in service contract loss.

An excerpt from the original list of supplier expectations is shown in Figure 1.

Rarely if ever do I have salesmen or service providers tell me they cannot meet my expectations or deliver on a promise. You’ve heard the saying, “Talk is cheap”? Not only should you hold your contract partners accountable to the commitments they make, but also you should audit their work while on site to determine whether their abilities match their promises. You will be amazed at what you see if you shadow technicians as they are completing PMs or, at minimum, immediately read their trip report and then go out and have a look for yourself. Are they missing warning signs that you readily identify?

My rule for service providers is this: If I, who never fixed an air compressor in my life, can spot potential failures that were not flagged on the PM just completed, then what am I paying them to do?

If this happens more than a couple of times, start looking for a new service provider. If you do find that rare gem – someone who is aligned to your vision and has the technical competency to deliver reliability-centered maintenance – do not let them go! I have a number of partners I rely upon heavily to help us achieve our asset health and TCO goals. They are out there but are hard to find!

Once you have established service-provider expectations, complete a failure modes and effects analysis (FMEA). We use a streamlined approach that I call FMEA object-type templates to capture the common failure modes and cause codes for a given asset class.

The FMEA object-type template failure mode/cause codes can be loaded into your computerized maintenance management system (CMMS). Figure 2 shows an example of how we capture meaningful failure mode, cause code, and mean time to repair (MTTR) data in our CMMS.

Where and how to take action

Two important “first-step” actions I strongly encourage you to take early in the journey if you haven’t already done so are to create part codes for every part used on your compressors and dryers and review any preventive maintenance (PM) plans that are part of your service contract.

Most service providers develop parts and labor contracts that list parts as a lump-sum item. When failure maintenance work is requested, the quote will usually list parts as one lump sum. Most end users have no record of parts usage or history. This approach does not support the reliability excellence model. By creating part codes for consumable stock items as well as order-on-demand parts and enforcing the use of part codes for all materials purchased, the end user can build a usage history in the organization’s CMMS.

Take a look at the PMs your OEM completes on your site. If the PM lists line items, see how many of them start with “inspect,” “check,” or “record.” Ask your OEM the following two questions.

  1. What does “inspect” or “check” mean?
  2. What happens if I do not do this task?

After you complete an FMEA for your compressed air equipment, take a look at the answers to the question, “What should be done to prevent or predict the failure?” Perform this PM optimization exercise as you assume ownership of recording and monitoring key operating parameters, and you’ll get rid of the majority of line items listed on the PMs. This will let you reduce visits to cover only those few items that truly require the service provider’s expertise.

One “value-added” service that OEMs promote that I agree is money well-spent is 24/7 continuous data monitoring. Whether you decide to purchase one of the OEM-supplied software packages or decide to land key operating parameters back to your DCS and data historian is up to you. Linking an OEM’s proprietary controllers back to your data historian can be tricky, but there are third-party controllers that use common platforms such as Allen Bradley ControLogix®. These controllers can be installed on most of the common compressors. We already had our Atlas Copco compressors set up for the Atlas Copco SMARTLINK® data historian even though we had let our subscription expire, so the choice was easy for us. SMARTLINK® can be used on Ingersoll Rand units also. If you have a mix of compressors as we do, it is possible to settle on one platform for all of your machines.

If you have several compressors at your site, a master control system is also a wise investment. Approximately 70% of compressor life cycle costs (LCC) come from energy. If you do not base-load some machines and optimize operation of the ones that are in trim mode, you will throw away hundreds of thousands of dollars in energy costs. Compressed air is considered the least-efficient source of energy available, and the absolute worst thing you can do is compress air and then blow it off to atmosphere. Data historians combined with a master control strategy and judicious use of air storage can markedly reduce energy consumption. Figure 3 shows a snippet from a centrifugal compressor at our site operating in trim mode after we optimized our compressor operating strategy.

Energy efficiency can also be greatly enhanced if you utilize ultrasonic emissions (UE) to detect and fix compressed air leaks. Many articles will tout the incredible savings that can be realized if a site adopts a UE leak detection program. But a leak detection program will not save you one penny if you don’t fix the air leaks that you find. And here’s a truth that proponents of using UE to identify air leaks often don’t mention: You have to combine an aggressive compressed air leak-detection program with a master control strategy for your site to realize the full energy-savings benefit. If you fix a ton of air leaks but do nothing to idle a compressor or two, you will just blow off that precious compressed air to atmosphere.   

As your asset management program gains traction, you will find there are opportunities to spend CapEx funds to optimize and fine-tune your operation. This is where using LCC analysis can help you make wise total-cost-of-ownership (TCO) decisions. We have already performed three LCC analysis case studies on our journey to “best-in-class” asset management. Early in our journey, we were faced with the decision as to whether we should overhaul one of our older units, an Atlas Copco ZR6, or replace it with a newer model. Total LCC indicated that replacing the unit with a remanufactured ZR750 was the better choice. The project had the added benefit of storeroom inventory consolidation, as we already had one ZR750 on site. Purchasing a second ZR750 created a great duty/standby pair of units to meet our site redundancy needs.

Our asset management journey started 3.5 years ago now. The results we have achieved have exceeded even our wildest expectations.

  1. Compressed air maintenance costs have fallen 63% over the five-year period that preceded the asset management strategy kickoff. We believe that our long-term sustainable cost reduction will be around 39%.
  2. So far, we have not had a rental unit in the plant since shortly after the strategy kickoff. We typically now operate with one large unit, and sometimes one large and one small unit in standby, giving us great flexibility when it comes to scheduling service.
  3. Energy use has dropped dramatically. Our conservative estimates are that we have reduced our energy use by 22%.
  4. We have had no OEE impact attributed to compressed air system equipment since program kickoff.

The most impressive thing is that we have accomplished these results with minimal capital investment. Basically, we just audited our practices; applied proven asset management principles; developed a written, detailed, action plan; rolled up our sleeves; and went to work.

In my opinion, it is difficult to employ a facility-wide or corporate asset management strategy that covers your entire asset base. There are usually too many other initiatives happening at any given moment. I find it is much easier to adopt a strategy asset class by asset class. It is just too big of a cultural hurdle to employ this strategy everywhere at once. It took a disastrous year for us to focus our attention on this important asset class. By employing the principles and practices outlined here, you, too, may enjoy the benefits of best-in-class results for your “fourth utility.”