What should an industrial instrument calibration record include?
A calibration record should show whether an instrument met its acceptance criteria before anyone adjusted it, what was changed, and whether it met the criteria afterward. A certificate that says only “passed” loses the evidence needed to detect drift, repeat problems and process risk.
Record the instrument and the test conditions
Use the unique asset tag, manufacturer, model, serial number, location and measurement range. Record the procedure revision, test date, person performing the work, reference instrument identification and its calibration status. Include relevant environmental and process conditions when they affect the measurement. The acceptance tolerance must be stated in engineering units, not left to memory.
Keep as found and as left values separate
- As found: actual readings at defined points before adjustment, including direction of travel where hysteresis matters.
- Decision: pass or fail against the approved tolerance, with the numerical error and any uncertainty considerations required by the procedure.
- Action: adjustment, repair, replacement or no change, with the work order reference.
- As left: readings after work, showing that the device meets the approved acceptance criteria.
- Exceptions: out of tolerance condition, impact assessment, notification and disposition of any affected process data or product.
Example: a pressure transmitter that drifted
A transmitter expected to read 100 psi reads 106 psi on the first test. The technician adjusts it and records 100 psi afterward. Without the as found value, the record conceals the drift. The reliability team cannot tell whether the device has a recurring problem or whether its previous readings affected a control decision. The record should preserve both readings and link the exception to a documented evaluation.
Apply the correct compliance boundary
For equipment within an OSHA process safety management covered process, 29 CFR 1910.119(j)(4) specifies inspection and testing practices and documentation including date, performer, equipment identifier, description and results. It does not mean every instrument at every plant is automatically subject to PSM. Apply the site's governing procedures, manufacturer guidance and applicable standards to determine intervals and tolerances.
Make the records useful
Store records against the correct asset in the CMMS or calibration system. Trend as found errors by tag, service and device family. Repeated drift may justify investigation, revised operating conditions or a different instrument rather than another routine adjustment.
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Technical references
OSHA Process Safety Management, mechanical integrity · OSHA interpretation of inspection and test documentation