As a reliability consultant, I have often been asked to assist with ‘making plants more reliable’.
The problem is that most business units do not have a definite value or description for reliability. Maintenance organisations often chase reliability, but when asked what do they want from ‘reliability’, it is met with a silent frown. Reliability is reliability, right?
Wrong. Reliability for each plant means something different. Even reliability within a plant has different requirements for different sections. For example, the skirting on a conveyormayonly need a reliability of 90%. If it fails, it may cause a bit of spillage, which can be cleaned up and the repair done during the weekly planned outage/ stop. But your fire hydrant needs a reliability of 100%. When that fails, the consequence can be dire.
What makes up Reliability
Reliability of plant is a function of effort (man hours & cost) vs risk vs reward.
“Reliability is a function of Effort vs Risk vs Reward” – D. Martins
Some businesses will run with low effort, high reward (i.e. high ROI) but also high risk. Where a failure will cause a significant impact on reward until repaired.
Other businesses again, will rather spend high effort, get relatively high rewards with a lower risk. Now I say relatively highrewards, as the reward is lowered due to the higher effort spent. The risk is also lower and the up time of the plant is more predictable.
Defining your Reliability
How do you define your Reliability? Below is a suggestion:
Rank the following three items in terms of importance in your business unit:
– Low Risk
– Low Effort (cost & man hours)
– High Reward
You need to identify your highest driver. Let’s say your highest driver is high reward in the form of high predictability of product delivery. It will entail a lower risk but effort will definitely increase. Your reliability is then defined as a: “High predictability of product delivery, while sacrificing cost to achieve this”.
Or, let’s say your highest driver is high reward in the form of high output, but you also want to do this at low effort, then your risk will also be very high. Your reliability is then defined as a “High ROI strategy, while accepting high risk of failures impacting delivery”.
This definition will be based on your business drivers, the culture of the business, the maturity of the business as well as the risk tolerance of the business.
Example: Crushing & Screening Plant
Take a crushing and screening plant for example. You could potentially spend very little on Preventative and Predictive Maintenance, deliver your tonnes at a (fairly) stable monthly rate (daily rate will be erratic) yet run the risk of catastrophic failure that could jeopardise your delivery for the month. This will give you a resultant low $/ton rate over a longer period of time.
Or, you could spend a lot of effort on Preventative and Predictive Maintenance, deliver at a stable daily and monthly rate with low risk of catastrophic failure, but your $/ton cost will be substantially higher (potentially double) than the first example.
If you are not seeing either of the two above, it may be necessary to start with defining your reliability, and then applying the 80:20 principle for your maintenance effort. (See previous article).
If you need assistance in defining your plant’s reliability, contact Asset Optimisation.