November 18, 2018, 3:07 pm

Reliability in Operations

In this article, we will explore some of the key ways in which Operators and Operations Management can impact on equipment reliability, and offer some practical suggestions for how they may be able to assure, and improve Reliability in Operations. This is the third article in a series of eight articles on Reliability Improvement.

reliabilityThe other articles in this series include:

 

Inherent Reliability vs Operational Reliability

In the previous article on Reliability in Design, we noted that “Inherent Reliability” (the level of reliability of an asset, as determined by its fundamental design and installation) differs from “Operational Reliability” which is the reliability of the asset actually observed in operation. In the context of reliability in design, it is important to realise that actual operating and maintenance conditions and practices vary significantly from those assumed by designers then Operational Reliability will vary significantly from Inherent Reliability.

While Operations has an important part to play during the Design phase of the asset lifecycle in ensuring that the assumptions made by designers during this phase are reasonable, Operations has an even greater part to play in ensuring that actual operating conditions and practices align, as far as is possible, with those assumptions made during the Design phase of the asset lifecycle. At the very least, there needs to be a realisation that, if operating conditions and practices vary from those assumed by designers, then there may be an adverse impact on system reliability, and that operating performance may vary from expectations.

The Journey to Operational Excellence

Before we consider Operations’ role in assuring and improving reliability, let’s first consider Ledet’s model of Operational Improvement, illustrated below.

reliability operations improvement

Figure 1 - Journey to Operational Excellence

An explanation of this model in its totality is beyond the scope of this article, but let’s briefly outline the key elements. Ledet and his associates proposed that, based on their experience in improving operational performance at Dupont Chemicals and Specialities in the 1990s, that individual work sites tended to operate in one of five “domains” – those entitled, “Don’t Fix It”, “Reactive”, “Planned” etc. in the above diagram. Clearly, organisations want to move to the right in this diagram – the aim, as a minimum is to move into the “Proactive” domain. In order to move into the next domain, organisations need to focus on improvement in specific areas (for example, “Predict, Plan, Schedule, Coordinate” for the Planned Domain.

How can Operators impact on Reliability?

When considering the Ledet/Dupont model for excellence, operators play an important role in helping to predict and avoid failures through early detection.

reliability operations

There are some key elements of basic equipment care that operators need to adhere to:

  • Understand the assumptions made by Designers regarding operating conditions and practices
  • Understand Equipment Capability and Limitations
  • Operate Equipment within its Limitations and in line with the operating conditions and practices assumed by designers
  • Treat Equipment with TLC
    • Tighten
    • Lubricate
    • Clean
  • Inspect/Check equipment for obvious incipient faults, and either fix them, or report them

Fundamental to all of these things is the underlying philosophy that Operations “owns” the equipment – or at least that they treat it as though they owned it. What we want to avoid is the “hire car” mentality that exists in many organisations where operation’s view is that all the equipment needs to do is to survive until the end of my shift (or when I return it to the hire company), and then it becomes someone else’s problem if it fails.

Understand and Operate Equipment within its Limitations

Some key things that can be done to assist operators to operate equipment within its limitations and in line with assumed operating practices and conditions include:

  • Identify Critical Operating Parameters
  • Understand and Set Operating Limits/Envelopes
  • Communicate these to Operators
  • Set alarms, monitor and control overrides/bridging
  • Make it easy for operators to see when equipment is operating outside limitations
  • Identify critical operating activities where overloads/equipment damage is possible
  • Train Operators to avoid those situations/perform those activities reliably
  • Monitor, audit and enforce compliance

window gaugeMaking it Easy for Operators

Visual guides and aids can be much more effective in conveying information. Consequently consideration of operator use needs to be made as part of the design. In terms of the operation and use of equipment, visual simple visual instructions / single point lessons can help ensure correct operation and use. Sight glasses rather than the use of dipsticks are a good example.

Some Critical Operator Activities Which Can Impact on Equipment Reliability

Examples of some critical operator activities which, if not done correctly, could adversely impact on equipment reliability are as follows:

Commencing downhill segment of haul route in mining truck. If the operator enters the segment driving too fast, then he will either:

  • Overspeed the engine, reducing its life, or
  • Incorrectly apply the service brakes, reducing their life

dump truckStarting/Changing Pumps

  • If an operator starts a radial-flow type pump with the discharge valve open, then the driver may become overloaded
  • If an operator starts an axial-flow type pump with the discharge valve closed, then the driver may become overloaded
  • If an operator does not open the discharge valve quickly enough after start up, the pump may overheat
  • If a pump fitted with mechanical seals has inadequate seal water flow, the mechanical seal may overheat

Equipment Lubrication

  • Operators are often responsible for lubricating equipment, and poor lubrication is the most common cause of rotating equipment failures.

equipment failure causes

Do you know what the critical operator activities are at your organization? Have instructions been developed to assist operators to perform these activities correctly? Have they been trained in these activities – and if so, how long ago is it since you checked for competence in these areas?

Operating with Precision

Another area operators can assist with improving reliability is through precision in operations by reducing variability.

operating precision

There are many sources of operational variability:

  • Variability in Raw Materials/Feedstock
  • Variability in Customer Demand
  • Lack of Clear Operating Parameters
  • Process Control Parameters/Tolerances
  • Differing Practices between Shifts
  • Shift Change
  • Equipment Reliability

The following is an example of how reducing variability, improving precision, can improve reliability as well as productivity and availability:

“The Improving Performance Together (IPT) asset management program payload management initiative delivered further improvements across many of the Group’s mines in 2009. The average load carried by the Group’s haul truck fleet increased by an annualised rate of more than 100 million tonnes – more than the annual tonnes mined by the Mount Tom Price iron ore mine. The initiative reduced load variability by five per cent from 2008.” (Rio Tinto 2009 Annual Report)

The (hypothetical) graph below illustrates the variability in loads for a type of dump truck. From a reliability perspective, operation in the overloaded state would lead to premature failure of components as the truck is being operated outside of its designed capacity.

average truck

The graph below shows that through proper training and adherence to more accurate truck loading by loader operators and truck drivers, fewer trucks would be subjected to overload conditions. Fewer overloaded conditions increased truck reliability and lead to fewer failures. Also from an operational perspective, higher average loads per trucks means more carriage of material which can mean either fewer truck loads required to meet daily production needs (which may lead to a reduction in truck fleet size), or more material being able to be delivered for production.

average truck load

Coordinating Operations and Maintenance for Reliability

The final are where Operations can impact on reliability is by ensuring that equipment is released to Maintenance when preventive maintenance is required. Early detection is one aspect of operator care but then allowing the fault to be fixed is the next step. It is better to fix an oil leak than replace a seized engine. Similarly, failure to release equipment for scheduled inspections or servicing also increases the risk of premature failure. Once the maintenance plan has been agreed between Operations and Maintenance, then both parties should make an agreement to stick to it. It is there for a reason.

fix now

Conclusion

This article has outlined some of the key ways in which operations can impact on equipment reliability, and offers some suggestions for activities that Operations can undertake to assure equipment reliability. It is the third in a series of articles, with the remaining articles in the series consisting of the topics:

If you would like to receive early notification of publication of future articles, sign up for our newsletter now. In the meantime,if you would like assistance in establishing effective reliability in operations within your organisation, please contact me. I would be delighted to try to assist you.

Sandy Dunn

Director

 

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