If you’re someone who has been reading my blog posts the last several years I believe it is quite evident that I love facilitating RCM events.  While there are several reasons for this they all boil down to the fact that I enjoy working with the maintenance and operations people and showing them how they have the power to improve equipment reliability.  Reliability Centered Maintenance is designed to identify and mitigate the failure modes that result in the functional failures of your assets.  Your people fact are the experts when it comes to how these machines should be operated and maintained, the reality is no one has ever asked them what needs to be done and if they have they didn’t listen.

nut-n-boltNow, while I truly enjoy this process there are certainly times I have become frustrated as a facilitator and there are certain failure modes that come up on a frequent basis that make me stop, take a deep breath and roll into what I call a standard explanation as why the failure mode they just listed isn’t really a failure mode but a failure effect.

The most common; “The (name a part), failed, because the bolts came loose.

(I’m taking that deep breath once again as I write this.)

My standard explanation…

Really, the bolts came loose, isn’t that a failure effect?  How in fact did the bolts come loose, that would be the failure mode.  At this time someone will quickly answer that this machine vibrates a lot or this piping connection goes through thermal cycling.

I ask the question; don’t all those things happen to the drive train on your car?  Doesn’t your engine get hot; doesn’t the entire drive train vibrate and bounce as you go down the road?

Nearly everyone in the room will agree with this statement.

Ok, so how often do you have to tighten the bolts on your drive train?  I mean if bolts just came loose wouldn’t auto makers set up a PM to have you bring your car in every six months or so to tighten all the bolts back up?

The team is now looking at me, I must be turning red again so I take yet another deep breath and ask.

Why don’t the bolts on your drive train come loose?” In my lifetime I have had more than 10 vehicles, I have been driving for over 37 years, and have driven I’m sure over one million miles and in all of that time I have never had a drive train bolt come loose.  Why don’t they come loose?

Someone quietly speaks up; “Is it because they torque them”.


So can someone please explain why your bolts are coming loose?

Because we don’t have torque wrenches available to use, we sometimes use the wrong grade of fasteners or reuse the nuts and bolts, and we rarely use Loc-tite?


The team is typically smiling; they can see that my breathing is close to normal now so I ask one final question.  So, if bolts just don’t come loose, please let me know the cause.  What caused your bolts to come loose?

They all wait for someone to speak up, finally someone says the two words us maintenance guys always try to avoid.

Improper Installation – The bolts are loose due to improper installation!

The truth, bolts don’t just come loose, we don’t tighten them properly.  So take some time today to be proactive, go out and purchase a few torque wrenches, and some Loc-tite.  Put together a quick training class on how to use a torque wrench as well as proper torqueing patterns and for my sanity, please remember to get rid of that PM that gives people time to go check for loose bolts!

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2 Responses to Do You Have A Screw Loose?

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  2. Bob Marlie says:

    I have attempted to discover data on strings, screws, fasteners, and pipes strings. Your site provided for me much data about the threads. Thanks for sharing this information.

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