OMDEC - Optimal Maintenance Decisions Inc.

1. Haul Truck Motors – Coal Mine

• Project was completed in 2001 on 26 trucks, 55 motors.
• EXAKT reduced Mean Time Before Replacement from 19,700 to 13,500 hours.
• Failures dropped from 100% to 26% (this is the minimum cost level based on the Company’s ratio of Preventive Replacement cost to Replace on Failure cost (1:3).
• Total fleet maintenance costs for the motors dropped from $1.46m to $1.09m for an annual savings of $371,000 or 25%.
• If the 1:3 ratio was increased to 1:6 for example to take account of these other real costs of failure, then the annual savings are $1.46m. (Note 1:6 is still very low by normal commercial standards)
• Other commercial benefits not included in the calculations:
  • higher revenues from fewer failures and less downtime
  • reduction in fleet size due to fewer and shorter out-of-service conditions
  • avoidance of contract penalty costs due to non-delivery

2. Circulating Pumps – Liquid Fuel Production

• Project was based on historical data from 8 pump bearings involving 11 failures.
• Original Replace on Failure policy caused swap outs at 404 days; company had shifted to 215 days to reduce the failure rate.
• EXAKT recommended 263 days, dropping failures to only 4.
• Cost of failure included replacement costs and loss of production. Failure replacement took 8 hours and contribution to the company was valued at $4460 per hour per pump.
• Annual Replace on Failure cost was $306k versus the cost of the Company’s current policy of $261k.
• EXAKT’s recommended policy reduced costs to $162k for savings of about $100,000 compared to the current policy, and $140,000 compared to Replace on Failure. This represents a cost reduction of 38%.
• No account was taken of the benefits to the Company resulting from:
  • Avoidance of contract penalty costs
  • Loss of reputation with customers
  • Government penalties due to environmental spills and safety issues

3. Nuclear Fuel Rod Seals

• 30 seals examined with a history of 25 failures.
• Existing policy was Replace on Failure at 657 days – cost was $4.56 per replacement cycle.
• EXAKT’s proposed Preventive Replacement policy reduced this to $3.56 per cycle for a savings of 22%
• Time involved in failure replacement only was considered.
• No commercial benefit was calculated for protecting the revenue stream from power generation losses or loss of reputation as a result of power fluctuations and brown-outs.

4. Gear Boxes

• 11 single reduction helical gearboxes were run to failure on a test-bed
• considering only failure repair versus preventive replacement cost, the cost reduction from applying EXAKT was 33%
• no additional cost data was measured

5. Copper Mine – Haul Truck Motors

• Project was conducted on Rocker Arm Gaskets in the haul truck motor; a sample of 92 with 9 recorded failures was used.
• Replace on Failure policy showed expected time between replacements of 3677 hours, for an annual cost of $26m.
• EXAKT recommended to replace on 2705 hours for an annual cost of $20m
• Annual cost reduction is 23% or $6m
• EXAKT data was extracted from Mincom Ellipse

6. Chemical Processing Plant – Compressors

• Company produces feedstocks for petroleum production
• Equipment was two stage hydrogen compressor – sample size was 45 with 37 recorded failures.
• Data was extracted from Datastream MP2.
• Phase 1 of the project concentrated on understanding concepts and setting up the data collection process
• The Final Report said “EXAKT established the links between Condition Based Maintenance (CBM) data and failure; confident failure predictions and optimized maintenance decisions using EXAKT will be possible shortly”

• 21 condition variables monitored; of these only three proved to have a significant impact on the failure mode
• This resulted in a “significant reduction in data collection and analysis costs”
• EXAKT’s preventive replacement recommendation led to 55% reduction in costs compared to the Company’s practice of Replace on Failure
• Preventive replacement led to a 10% increase in equipment life and a corresponding reduction in capital cost
• No other financial data is currently available
  

8. Light Rail Transit System – Wheel Bearings

• Company had excessive failures of traction motor bearings – up to 9 per year.
• Bearing failures cause serious loss of confidence in rider safety.
• EXAKT added one critical variable to be monitored – bearing grease colour and recommended the Inspection Interval be reduced from 3.5 years to 1 year
• EXAKT recommendations:
  • reduced the units’ maintenance costs by 55%
  • reduced failures from 9 to 1
  • reduced Condition Based Maintenance data collection costs by $3m annually

9. Pulp Mill – Pump bearings

• 33 bearing histories were examined in 8 pump locations, including 11 failures.
• EXAKT recommendation would have prevented 10 of 11 failures, and reduced the Mean Time Between Replacement by 7% (from 571 to 529 days)
• This resulted in a cost saving of over 30%
• based on a ratio of Preventive Replacement cost to Replace on failure cost of 1:3
• no account was taken of revenue protection caused by the lower failure rate or of damage to reputation from environmental spills