Start with an instrument register
Before any AMC discussion, list every instrument with tag number, type, make, model, range, location and criticality. Without this list, quotations are guesses and disputes appear at the first breakdown call. The register is also the backbone of your calibration schedule.
Define what the contract covers
| Element | Questions to settle up front |
|---|---|
| Preventive visits | How many per year, how many engineer-days per visit, which tags per visit |
| Calibration | On-site or lab, number of instruments, certificate format, traceability |
| Breakdown support | Response time, whether visits are included or charged, escalation contact |
| Spares | Consumables included, major spares charged at actuals, recommended stock list |
| Documentation | Service reports, certificates, updated register after each visit |
| Exclusions | Damage from misuse, third-party modifications, civil or electrical work |
Scope by criticality, not headcount
Splitting the register into safety-critical, quality-critical and operational instruments lets you buy frequent attention where it matters and lighter coverage elsewhere. A plant with 400 instruments rarely needs all 400 serviced at the same frequency.
Agree the schedule against your shutdowns
Line up major preventive work with planned shutdowns so instruments that need removal can be pulled without lost production. Instruments that can be verified in place go into the between-shutdown visits.
Insist on documentation you can audit
- Calibration certificates with as-found and as-left values
- Traceability of the reference standards used
- Service reports listing every tag touched and the work done
- An updated due-date list after each visit
- Observations and recommendations, including instruments that should be replaced
Review the contract annually with data
At renewal, look at breakdown frequency by tag, out-of-tolerance results, and instruments repeatedly repaired. That data tells you where to shorten intervals, where to extend them, and which instruments should be replaced rather than maintained.