The Ultimate in Machine Inspections

Wes Cash, Noria Corporation
Tags: lubrication programs

Being a consultant in the reliability field, you often get to see the latest and greatest in condition-monitoring tools and predictive data. It is very easy to get hung up on these tools and overlook simple machine inspections as a source of valuable information. If you have ever sat through one of my presentations or courses, you will often hear me refer to lessons taught to me by my grandfather. Perhaps one of the most influential came when I was a senior in high school working on my Suburban that was giving me problems.

After what seemed like days pouring through a Chilton manual and trying to diagnose some erratic noises and performance issues, my grandfather came to the shop to see how it was going. He asked me to start the vehicle. He listened to if for a moment and then pulled a dollar bill out of his wallet. He placed the dollar bill over the exhaust pipe and watched how it moved. He then put the bill back in his wallet and informed me that I had a burned valve. With that he left the shop and I was left to ponder what just happened. Come to find out, he was right, and I was amazed.

Some of the most impactful machine inspections can be carried out with minimal instrumentation, but it does require an individual that knows what they are looking for. While routine monitoring using vibration analysis, ultrasound, infrared, oil analysis and a litany of other technologies will always be important in providing hard, quantifiable data. The importance of daily inspections by operators and craftspeople cannot be overstated. Having a technician that is around the equipment daily is truly the first line of detection for abnormal conditions.

Early detection of potential failure is the key to minimizing the impact of those failures. While instrumentation will be able to detect faults with more granularity, few pieces of equipment get monitored everyday with these technologies. With the use of real time sensors is gaining popularity, these devices are often reserved for the critical 1-5% of machines. The remaining majority of the equipment falls into routine analysis that may be anywhere from weekly to quarterly analysis. This leaves far too much time between events and the likely hood of catching a failure early is greatly diminished.

However, by training the appropriate equipment on proper inspections; we now have the opportunity to watch the equipment in near real time. It is important to point out that during the failure mechanisms; the goal is to catch the failure as high up on the PF curve as possible. Predictive tools, when used correctly, can certainly catch a failure very high on this curve. Simple machine inspections can catch them high as well, provided they are doing the inspections to a high degree of thoroughness. Simply looking at oil levels and checking for leaks will not likely result in an early catch, but likely result in a “surprise” failure if not corrected.

Inspections can be thought about like using your senses to determine what is going on with your equipment. Often times when the term inspections is used, most tend to think only about visual inspections. While the majority of inspections will have a visual component to them, that is far from the only sense that should be used when ensuring equipment is functioning correctly. Your sense of smell, hearing, and touch are all just as powerful. We will breakdown inspection types by the different senses and discuss what can be determined using each of them.

Visual inspections

Visually inspecting a piece of equipment is more than just what you see, it should also include what you don’t see. As a machine operates, several things in and around it will likely change that indicate potential failures or faults. We can typically lump visual inspections into two categories; internal machine inspections and external machine inspections. Both can be performed at the equipment, but some are more intrusive than others. We want to minimize the exposure of the equipment to the outside environment as much as possible so many of these inspections will require modification of the equipment.

Internal Machine Inspections:

External Machine Inspections

Audible Inspections

When visiting different facilities and touring them with a seasoned maintenance or reliability professional; it never ceases to amaze me when they stop, pause and say “this machine doesn’t sound right.” Each machine has its own unique sound or serious of noises as it cycles through its operation, and subtle changes in those sounds may indicate an impending failure. While the use of listening devices such as ultrasound has gained popularity and is a great tool, just using a sounding rod, stethoscope, or the naked ear can provide useful information.

Tactile Inspections

While being in close proximity of moving equipment does present some safety concerns, your sense of touch can be extremely sensitive to different common failure modes and symptoms of failures. Being safe is paramount when performing these types of inspections and you should always adhere to company policies regarding equipment and wear the proper personal protective equipment. Some of the many conditions you can monitor using touch are:

Olfactory Inspections

Don’t overlook your sense of smell during your inspection rounds. This is a powerful tool, especially when it comes to diagnosing issues with lubricants. Many different compounds can be generated and exist within lubricants, all with their unique odor that, with time, can be identified. Perhaps one of the most common expressions heard when dealing with failed equipment is, “something smells burned.” This is an inspection type that does require some caution and it is always best to gently waft the smell towards your nose as opposed to bringing in a big breath. This is also an inspection that is best done from oil in a sample bottle as opposed to being in the field because of added vapors or fumes that may be present that could impact the sensitivity of your nose.


As discussed, many pieces of equipment come with the proper accessories to be properly or even easily inspected while they are in services. Thankfully there are many devices that can be retrofitted to most equipment to make these inspections a reality. While some may require more modification than others, there are many relatively simple modifications that can greatly enhance your inspection program.

By taking a step back from your current practices and designing a new inspection program utilizing some of these recommendations, you can expect to have a better insight into how your equipment is operating. While some of these may be easy to implement, most will require some additional training for maintenance, reliability, operations, or whomever is actually performing the inspections. Remember, each set of eyeballs that goes onto the plant floor is an inspector and as such, they should know what they are looking for!