Formula Used
Direct repair cost = diagnostic cost + parts cost + labor hours × labor rate.
Expected repeat failure cost = failure probability × (1 - repair success probability) × failure impact cost.
Repair strategy cost = direct repair with contingency + tax + downtime cost + expected repeat failure cost + energy penalty + residual safety risk.
Replacement strategy cost = replacement cost + installation cost - salvage value + tax + replacement downtime cost + residual risk.
Preventive strategy cost = preventive service cost + diagnostic cost + planned downtime + reduced failure cost + reduced energy penalty.
Defer strategy cost = monitoring cost + increased failure cost + increased downtime cost + safety risk + energy penalty.
Equivalent monthly cost = total strategy cost ÷ useful months inside the analysis horizon.
Physics View of Repair Strategy
Repair planning is not only an accounting task. It is also a physics problem. Every asset fails because load, heat, friction, corrosion, fatigue, or vibration changes material behavior. A repair strategy should connect those physical causes with cost and downtime. This calculator helps you compare repair, replacement, preventive service, and deferral in one place.
Why Failure Probability Matters
Failure probability describes the chance that the asset will stop meeting its function during the chosen horizon. A bearing, pump, motor, panel, valve, or test rig may still work today, yet its risk may rise fast under stress. Higher probability increases expected failure cost. It also raises safety exposure and lost production time.
Cost Is More Than Parts
A repair invoice can look small. The full cost can be much larger. Labor hours, diagnostic work, part lead time, downtime, energy losses, taxes, and contingency should be included. Energy penalty is important in physics assets. A worn component may consume more power, create extra heat, or reduce output. That hidden loss often changes the decision.
Repair Versus Replacement
Repair usually wins when direct cost is low, success probability is high, and remaining life is useful. Replacement may win when the asset has poor efficiency, severe risk, or short remaining life. Preventive service can win when planned downtime is cheaper than unplanned failure. Deferral only works when risk is low and monitoring is strong.
How to Read the Result
The calculator lists each strategy with total estimated cost and equivalent monthly cost. The best option is the lowest practical monthly cost after risk is included. Review the repeat failure probability too. A low cost option may still be weak when safety exposure is high.
Use Results With Judgment
Numbers support decisions, but they do not replace engineering judgment. Inspect the asset. Check records. Review operating load and environment. Confirm critical spares. Then compare the calculator output with safety rules and production needs. The strongest plan is usually the one that balances money, reliability, and physics-based risk.
When Inputs Should Be Updated
Update inputs after inspections, load changes, temperature spikes, repeated trips, quotes, or delays. Fresh values keep the strategy realistic and stop old assumptions from hiding urgent failure signals.
FAQs
What is an option repair strategy?
It is a comparison of repair paths. It reviews repair, replacement, preventive service, and deferral. The goal is to choose the safest and most economical action for a physical asset.
Why does this calculator include downtime?
Downtime can exceed the repair bill. A short repair may still cause lost output, missed tests, idle labor, or delayed work. Including downtime gives a more complete strategy cost.
How is repeat failure probability calculated?
It uses failure probability multiplied by the chance that repair does not fully succeed. This gives a practical estimate of risk remaining after the repair option is chosen.
When should replacement beat repair?
Replacement may be better when repair cost is high, remaining life is short, energy loss is large, downtime is costly, or safety risk remains unacceptable after repair.
What does preventive service mean here?
Preventive service means planned work before major failure. It can include alignment, lubrication, calibration, sealing, cleaning, inspection, part changes, and controlled downtime.
Can this calculator handle safety exposure?
Yes. Add an estimated safety or compliance exposure cost. The calculator applies it through risk probability, so hazardous assets receive stronger decision pressure.
Why is energy penalty included?
Damaged or worn equipment may waste energy. It may also create heat, vibration, or drag. Monthly energy penalty helps reflect hidden physics losses during operation.
Is the lowest cost always the best option?
No. Use the ranked result with judgment. A low cost path may still be unsuitable when safety, compliance, critical uptime, or engineering limits require a stronger action.