In the world of operations, maintenance and reliability engineering it’s a term that’s thrown around quite a bit. I used it a while back in a blog post stating that the failure modes that have the most significant impact on asset reliability are those that result from the context, environment and culture in which you operate your assets.
Not long after I posted the blog someone asked “does this mean most of the failures we see today result from improperly operating our equipment?”
After looking the question over a few times I wondered what this person was thinking when they wrote the question. Did they really think the term operating context only has to do with how we operate the equipment? Operating context is a really a common term in our field and it encompasses several things outside of how we actually operate our equipment.
I wanted to reply to the comment but before I jumped into giving my standard definition of the term, I did what I always do when it comes to reliability engineering terms, I pulled out my Nowlan and Heap RCM document and looked for their definition.
Interesting, they didn’t use the term, they considered operating environment in the RCM document. I have always considered operating environment as part of the operating context.
So I Google searched the term expecting to find a few clear definitions from some known source on equipment reliability.
It seems the world of cellular phones has coined a clear definition, it states “The operating context is the hardware and software environment in the device, the target user, and other constraints imposed by various other stakeholders, such as a carrier.”
Interesting but not at all what I was looking for.
I then sat down to draft up my own personal definition of what I believe operating context means.
Operating Context – The current condition, environment, and culture in which you operate a piece of equipment. This would include but not be limited to the following:
- Temperature (Hot,Cold or severe swings)
- Dirty or dusty atmosphere
- Wet or dry area
- Corrosive, erosive or abrasive environment
- Dark or dimly lit
- Culture (Goals and expectations not clearly defined, high level of emergency/demand work)
- Operating outside design expectations or performance standards
- Asset condition (Loose, improperly supported, improperly installed, improper design, damaged)
- Improper operation (Start up, shutdown, product change, setting, speed, flow, pressure)
- Human error (I forgot, no check lists or procedures)
When I think of how the operating context of an asset changes the failure modes and then of course the mitigating tasks or actions one would have to implement and perform to achieve a high sustained level of reliability always think about the pump in the picture below.
The company who owned and operated this asset was attempting to implement a PdM program using vibration analysis, oil analysis and infrared thermography and were quite frustrated that while they could detect high vibration, heat and metal particles in the oil, each time they replaced the pump or motor the unit would almost immediately go back into alarm.
Just by looking at the attached picture one can see several problems with the installation of this pump and motor. Each of the issues listed below are
now impact the operating context for this asset;
- There is no foundation; the unit base is bolted to the floor.
- The base is made out of a piece of plate steel and does not allow for precision alignment.
- Two of the anchors are loose, the pump and motor are never aligned or secured,
- There are flow restrictions immediately in front of the pump suction.
- There are no piping supports for over twenty feet on the suction and discharge piping.
- The area in which this pump operates is wet, dirty and dusty.
Things that are not visible in this picture that also impact the operating context of this pump;
- Two of the eight bolts that hold the pump and motor in place are missing.
- The pump is started from a PLC, suction and discharge valves are opened automatically, it is normal for this pump to cavitate for thirty seconds or longer each time the pump starts.
- The pump is stopped and started a minimum of ten times a day.
- The pump and piping are cleaned with a strong basic solution at least once a week.
Thinking about the ten items I listed that impact the operating context of this asset it’s important to understand that there is several failure modes associated with each of these that now have a direct impact on the reliability of the asset. Only two or three would in any way be seen as
improper operation of this pump;
- Improper start up
- Improper shutdown
- Restricting the suction or discharge valves
Prior to performing a RCM analysis on this asset in 2003 the MTBF (Mean Time Between Failures) for this pump was 6.3 months. Several redesigns were recommended to eliminate the failure modes for the issues listed above. In the ten years following implementation, the pump has yet to fail. Still using the three PdM technologies they started with, they have received only one alarm, the motor was running at a high temperature in the summer and was contaminated with cardboard dust. Once the motor was cleaned the motor returned to normal operating temperature. A cleaning task identified in the RCM had been skipped for several months, had the task been performed as designed, the unit would have also run 10 years with no alarms.
The important thing to remember is our equipment was designed with precision in mind to operate within specific performance standards. Those of us, who design, operate and maintain these assets impact the operating context, environment and culture that will create or eliminate failure modes.
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