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What is the Correlation Between Safety & Reliability?

By Joseph Pitman, President, EAM at SEAM Group

September 2020

In the asset management world, can we draw a correlation between safety and reliability? At first glance, most people would say “yes.” The more reliable the asset, the safer it must be, and the safer the asset, the more reliable it must be. True? False?

Well, the answer is more complex than the binary yes or no.

I began pondering this question many years ago when traveling the country as a young consultant. Back in those days, I was in a different hotel room every week – in a different city and seeing a different customer.

During one of those many trips, I got up one morning and hopped into the shower. Since it was just me in the room, I didn’t think twice about leaving the bathroom door open. Personally, I like to take a hot shower, and before long, the room filled with steam.

Since the bathroom door was open, the steam waffled out into the adjoining room. After a few minutes of this, the hotel’s smoke detector suddenly sprang to life with its screech. What is this? Did I do that, I wondered?

In less than a minute, I finished my shower and quickly got dressed. I knew that when one smoke alarm goes off, all of them go off, so I wasn’t certain if the steam-filled room caused the problem. Maybe someone pulled the alarm?

With the shower off and exhaust fan running, the room began to clear of steam. The alarm was still blaring, so to test my theory of whether I was the culprit, I started waving a towel back and forth in front of the smoke detector. Within a minute, the alarm suddenly stopped. Interesting.

I still could not be certain if I set off the alarm. It could have been a coincidence. Since I am inquisitive by nature, I tested my theory at home, and sure enough, smoke alarms are sensitive to steam. This got me thinking. The smoke detector isn’t too reliable if steam can set it off, but is it safe?

Well, the answer is yes. It is very safe. Almost everyone has experienced the overly cautious smoke detector doing its job when it detects the occasional burnt toast or overcooked dinner. The house isn’t on fire, but the alarm doesn’t know that. It only detects the presence of smoke, so it alarms.

We see this contrasting relationship between safety and reliability all the time in the military, aviation, manufacturing, process refinement, consumer products, etc. Being safe doesn’t always correlate to being reliable and being reliable doesn’t always mean being safe. It is important to understand this certitude, or else you may be lulled into a false sense of security.

I’m former military, and I can attest that we used a lot of equipment that was highly reliable but inherently unsafe to operate. Conversely, as a homeowner, I own a number of assets around the home that are very safe but not always reliable.

As for safety professionals, we need to be conscious of the potential dichotomy between safety and reliability. Being safe doesn’t always translate into being reliable and being reliable doesn’t always translate into being safe.