Preventive Maintenance & Calibration Planning SOP
A preventive maintenance and calibration planning SOP for instruments under a service agreement: criticality assessment, interval determination, scheduled maintenance, drift-trend analysis and evidence-based interval adjustment.
How it works
Replace the lanes with your actual planning roles
This chart uses Account Management, Calibration Planning, ServiceDesk, Field Service and QA & Documentation. If a different role owns criticality assessment at your site, or scheduling sits with the same person who plans intervals, merge or rename lanes rather than leaving a lane whose owner nobody actually is.
Write your own criticality and interval rules into the row
"Assess criticality of each instrument" and "Determine calibration/service interval per instrument" are judgment calls in this chart, not lookups. Put your actual criticality tiers and the default interval each maps to in the row's comment field so the planner isn't reconstructing the rule from memory each cycle.
Decide what counts as evidence for tightening or loosening
"Adjust interval necessary?" only produces a defensible answer if "Analyze drift trends across calibration history" has a stated rule, for instance how many consecutive in-tolerance results earn a longer interval, or how close to the tolerance limit a passing result has to be before it counts as drift. Write the threshold into the row rather than leaving it to whoever is reviewing that cycle.
Confirm the two handoffs actually connect
"Perform preventive maintenance and calibration check" and "Flag instrument and hand off to Out-of-Tolerance Calibration SOP" both point at other SOPs in this set. Make sure whoever owns Field Service in your adaptation knows to open the matching SOP at that step rather than treating the row label as the whole procedure.
Set People and Workload on every row before you rely on the BI panel
The workload panel can only total hours for rows that carry them. Fill in People and Workload using realistic effort hours, not elapsed time, so a customer with a large instrument register actually shows up as a heavier planning and analysis load for the right person.
Frequently asked questions
How is this different from just running the Instrument Calibration & Documentation SOP on a schedule?
The Instrument Calibration & Documentation SOP is the single-visit procedure: as-found readings, tolerance check, as-left readings, certificate. This SOP is the layer above it that decides which instrument gets visited when, and what a visit's result does to that instrument's interval afterward. "Perform preventive maintenance and calibration check" hands off to that procedure rather than repeating it, and "Update instrument register and calibration history" is where this SOP's own work gets recorded.
What happens if a scheduled visit finds the instrument out of tolerance?
The "Result within tolerance at this visit?" decision routes a failing result to "Flag instrument and hand off to Out-of-Tolerance Calibration SOP", which owns the customer notification and impact assessment. The result still flows into "Analyze drift trends across calibration history" afterward, because a failure is exactly the kind of evidence a future interval decision needs, not something to leave out of the history.
Who decides whether an instrument's interval gets tightened or loosened?
In this chart that is the "Adjust interval necessary?" decision, owned by calibration planning. It runs off "Analyze drift trends across calibration history", which compares the instrument's full history rather than the latest result alone, so a single lucky pass doesn't loosen an interval that should still be tightening.
Does every instrument in the register get the same interval?
No. "Assess criticality of each instrument" happens before "Determine calibration/service interval per instrument" precisely so a process-critical instrument and a low-consequence one on the same customer site can land on different intervals from the start, before any drift-trend evidence exists to adjust them further.
Can this SOP run without a formal service agreement in place?
The chart assumes one, since "Review customer instrument register" is scoped to instruments under agreement and the interval-adjustment loop is what that agreement is selling. For a customer without an agreement, drop the account-management lane and treat each cycle as a standalone planning exercise rather than a recurring one.