A) The Background
Engineers have tried to address the issue of Reliability of equipment and systems in various ways. Therefore, many methods and techniques are in existence. The usual approach pivots around the concept of “failure modes” and how best to guard against those so as to prevent the consequences of failures. However, the existing methods do not take into account, flow of energy as an important factor that determines reliability of plant and machinery.
Taking this into consideration, I am putting together some rules and principles that hopefully point to a path that might enable engineers to improve plant reliability with minimum effort, resources and time.
But before I do that I would like to put forward an easy understanding of the term — reliability.
B) Reliability of a Machine:
The period of time a machine would run (fulfils its function) without a problem or trouble.
Longer the period of trouble free running better is the reliability of the plant.
It therefore addresses the heart of reliability improvement — i.e. enhancement of useful operating life of a machine or a system of machines.
C) What does that mean in terms of energy flow?
We may say that a machine that can continue with the smooth flow of energy, with the minimum wastage of energy for a long period of time is more reliable than a machine where energy flow is disrupted frequently in some manner or the energy wastage is high or the energy is pushed out of equilibrium condition, which invariably stops the machine from functioning effectively.
D) So what might be the job of engineers?
It is evident that the fundamental job of engineers (both operation and maintenance) is to run and maintain a machine or system in such a way so that the energy wastage is minimized and smooth flow is ensured for a long or desired period of time.
E) How can this be done?
This may be done in three fundamental ways, which are as follows:
- Observe the dynamics of a machine or system to ascertain energy flow patterns and the degree of energy wastage and the reasons for such wastage. Also determine the degree of stability or instability of the system and what affects a system’s stability.
- Adjust or maintain the conditions within its operating context to ensure smoother flow of energy with minimum wastage. In the process, learn what changes in a machine/system would disrupt energy flow or push it out of equilibrium conditions and prevent such disruptions.
- Change, monitor, modify the system (made up of physical asset and components, process, information flow, analysis and decision making, teams) as necessary, for smoother flow of energy to continue over longer period of time with minimum energy wastage.
F) How to apply it in a real plant?
I have found the following method useful in various plants where I implemented Reliability Improvement Programs.
- Make a list of critical machines.
- Select a critical machine along with its sub-systems (machines that support its functioning)
- Apply the three steps as outlined in Section E (above) — within the operating context.
- Improve and stabilize performance; record the learning.
- Create a custom made monitoring system to spot changes in time along with custom made expert system to guide engineers to quickly decide the course of actions to be undertaken.
- Record the decisions, actions and changes in the form of equipment history.
- Move to the next critical machine and its sub-systems.
- As we go along, first check whether the all consequences of failures have been taken care of. Next check whether overall plant/area/section MTBF (Mean Time Between Failures) is going up and whether MTTR (Mean Time to Repair) is going down along with consequential lowering of maintenance and operation costs. Lastly check the accuracy of the custom made expert system (usually made up of multivariate parameters) in is ability to forewarn and guide maintenance decisions.
G) General Rules:
Keeping the above in mind I formulated the following four rules that might help engineers managers stay on the path of plant reliability improvement:
- For any machine, energy tries to move in sync through all elements of a machine through various interfaces against many contradictions and constraints but always choosing the path of least resistance.
- Changes in contradictions, constraints and interfaces change the quality of energy flow forcing energy flow to go out of equilibrium (instability) to either cause degradation of performance or cause failures that lead to unwarranted plant stoppages, affecting costs and productivity.
- Changes and the causes of such changes are reflected in the dynamics of a machine in terms of interdependent parameters like vibrations, heat, flow, wear, humidity, temperature, pressure etc.
- Reliability of any machine or system can be improved by either maintaining the contradictions, interfaces and constraints to “just right conditions” or changing those to enable smoother flow of energy for a longer period of time with minimum wastage.
Having applied these basic rules some industrial plants were able to gain on-going benefits for years. Here are some examples of — Plant Wide Reliability Improvement