Reliability Engineering

Following the principle of Docendo discimus, (Latin "by teaching, we learn"), I decided to speak on Process Plant Maintenance, at an upcoming symposium, leaving 9 other plum topics to my good friends. It is a subject that evokes the depressing picture of a greasy-faced worker in blue overalls with spanner and wrench in hand. Being the prime mover of the symposium, I can take liberties with titles and so I decided to sex it up by renaming it “Reliability Engineering”. My mandate to each speaker is to fire 10 takeaway bullets in 20 minutes. So here are my 10 bullets on “Reliability Engineering” as applied to Chemical Industry. 

1)   The Bathtub Curve
 
The diagram is self-explanatory. The trick is to be able to tell the transition times and prepare accordingly.

2)   Four Kinds of Maintenance

a)   Breakdown maintenance

b)   Preventive maintenance

c)   Predictive maintenance

d)   Reliability centered maintenance

3)   Maintenance Cost

a)   Downtime cost : Loss of production

b)   Spare part cost (including the cost of carrying it)

c)   Special tools, tackles and rigs

d)   Specialist engineers/technicians

e)   Stress of shutdown and restart

f)    Risk of collateral damage

4)   Design to Minimize Maintenance

Examples : a) Oil mist lubrication. b) Low speed machinery which will improve bearing life.

5)   Validation of Design Assumptions

Periodic maintenance should revalidate design assumptions like fouling factor (heat exchangers) and air ingress (vacuum system)

6)   Access for Maintenance

Poor access will increase time and cost and can compromise safety. To be addressed in design phase by maintainability study.

7)   Safety During Maintenance

~30% of fatalities in manufacturing industry are associated with maintenance activity.

8)   Emergency Equipment

Periodic health check for safety valves, shut-off valves, firefighting equipment etc

9)   Spares Management

To stock or not to stock?

10)  Internet of Things (IoT)

Sensors embedded in equipment check for abnormal conditions and trigger work orders when safe operating limits are breeched. IoT is expected to move Reliability Engineering into a whole new orbit.