Define what the verification must decide before the machinery is run.
Post-overhaul verification can answer different questions: whether the machine is safe to return to service, whether vibration returned to its healthy baseline, whether a suspected forcing mechanism changed, whether an installation defect remains, or whether a named maker, project or contractual criterion is met. Those questions need different evidence. Record the decision owner, controlling requirement, required operating state, witness expectation and action if the result is inconclusive.
Vessel machinery condition monitoring is appropriate when the decision depends on repeatable baseline and trend evidence. Marine machinery vibration analysis is appropriate when spectra, waveform, phase, order or controlled operating comparisons are needed to investigate a symptom. Neither service automatically constitutes class approval, maker acceptance or an approved-service-supplier activity.
| Record ID | Machine / work | Decision required | Requirement / revision | Acceptance owner | Witness | If inconclusive |
|---|---|---|---|---|---|---|
| VER-___ | ___ | ___ | ___ | ___ | ___ | ___ |
| VER-___ | ___ | ___ | ___ | ___ | ___ | ___ |
Record exactly what changed and what did not.
“Overhauled” is too broad for diagnosis. Identify bearings, coupling elements, rotor, impeller, seals, alignment shims, soft-foot correction, balance weights, foundation fasteners, resilient mounts, pipe supports, lubrication, control settings and connected equipment that were inspected, renewed or adjusted. Keep the work report, clearances, torque records and alignment results available. A change in support stiffness, mass, process setting or pipe strain can alter the measured response even when the rotating assembly is sound.
| Item | Before condition | Work performed | After setting | Evidence reference | Potential vibration effect | Verified by |
|---|---|---|---|---|---|---|
| CHG-01 | ___ | ___ | ___ | ___ | ___ | ___ |
| CHG-02 | ___ | ___ | ___ | ___ | ___ | ___ |
| CHG-03 | ___ | ___ | ___ | ___ | ___ | ___ |
Also record components deliberately left unchanged. If a recurring defect could originate in the driver, driven machine, coupling, base, structure, process or connected pipework, the scope should not imply that work on one component eliminated the entire system-level cause.
Confirm that the comparison record is genuinely comparable.
A healthy pre-overhaul baseline is valuable only when its source and conditions are known. Check asset identity, point photograph, direction, sensor and mounting, measurement quantity, amplitude convention, frequency range, record length, processing, speed, load, temperatures, valve or damper position, vessel state and nearby machinery. If the old record lacks these details, retain it as context and establish a new controlled baseline instead of calculating a precise improvement.
| Comparison item | Baseline evidence | Post-work evidence | Same / different | Material effect | Usable? | Limitation |
|---|---|---|---|---|---|---|
| Point and direction | ___ | ___ | ___ | ___ | ___ | ___ |
| Quantity and bandwidth | ___ | ___ | ___ | ___ | ___ | ___ |
| RPM and load | ___ | ___ | ___ | ___ | ___ | ___ |
| Equipment lineup | ___ | ___ | ___ | ___ | ___ | ___ |
If the baseline and retest differ materially, report the new condition and the limitation. A percentage reduction calculated from incompatible measurements can be more misleading than no comparison.
Measure the machine train and the transmission path needed by the decision.
Assign point IDs to the driver and driven-machine bearings or casings, coupling sides, mounts, base or foundation and relevant connected structure. Record horizontal, vertical and axial direction, attachment, surface condition, sensor identity and photograph or drawing reference. Use shaft-relative probes, casing acceleration, velocity, displacement, phase or process measurements only when the machine design and decision justify them. Do not merge unlike quantities into a single undefined vibration number.
| Point ID | Component / location | Direction | Sensor / attachment | Quantity / units | Photo reference | Purpose |
|---|---|---|---|---|---|---|
| PT-___ | ___ | ___ | ___ | ___ | ___ | ___ |
| PT-___ | ___ | ___ | ___ | ___ | ___ | ___ |
| PT-___ | ___ | ___ | ___ | ___ | ___ | ___ |
Where work involved alignment or soft-foot correction, include both sides of the coupling and document the hot/cold state where relevant. Where a mount or foundation changed, include upstream and downstream points needed to distinguish lower machine motion from increased transmitted response.
Control the state that produces each measurement.
Vibration can change with RPM, electrical or mechanical load, flow, pressure, temperature, valve position, generator combination, thruster use, vessel speed, propeller condition and nearby equipment. Agree safe steady holds, controlled transitions and process targets with the vessel team. Log each run and any deviation. A berth check may verify assembly and gross behaviour but may not reproduce the sea-going load needed for final comparison.
| Run ID | RPM / frequency | Load / process | Equipment lineup | Temperatures / pressures | Vessel condition | Deviation |
|---|---|---|---|---|---|---|
| RUN-01 | ___ | ___ | ___ | ___ | ___ | ___ |
| RUN-02 | ___ | ___ | ___ | ___ | ___ | ___ |
| RUN-03 | ___ | ___ | ___ | ___ | ___ | ___ |
Allow stabilization after start-up and after each load change. Keep the time relationship between vibration, tachometer or phase reference and process values. If a protective trip, abnormal temperature, leakage or unsafe response occurs, stop according to the vessel’s authorised procedure; a measurement plan does not override operational control.
Make the data traceable before interpreting it.
Record analyser, transducer, calibration or verification status, cable and channel assignment, mounting, orientation, sensitivity, sampling rate, frequency range, window, resolution, averaging, integration and amplitude convention. Review overloads, clipping, loose mounting, poor contact, cable movement and unexpected noise while access is still available. A valid calibration certificate does not correct the wrong point, direction, bandwidth or operating condition.
| Setup ID | Instrument / sensor | Certificate / field check | Mounting / orientation | Range / resolution | Processing | QA status |
|---|---|---|---|---|---|---|
| SET-___ | ___ | ___ | ___ | ___ | ___ | ___ |
| SET-___ | ___ | ___ | ___ | ___ | ___ | ___ |
For an overall-value verification, retain enough raw or spectral evidence to investigate an unexpected result. For speed-dependent machinery, include a reliable speed reference where practical. For transient events, keep time records long enough to connect the response with the operating change.
Separate absolute level, change from baseline and diagnostic evidence.
Review at least three views. First, compare the defined quantity with the confirmed machine-specific maker, project or applicable standard basis. Second, compare like-for-like points with the controlled healthy or pre-work baseline. Third, examine whether spectral, waveform, phase, order, temperature, lubricant or process evidence supports the proposed mechanism. These views may not agree, and the report should show that rather than force one pass/fail conclusion.
| Point / run | Baseline value / pattern | Post-work value / pattern | Criterion | Condition differences | Interpretation | Status |
|---|---|---|---|---|---|---|
| CMP-01 | ___ | ___ | ___ | ___ | ___ | ___ |
| CMP-02 | ___ | ___ | ___ | ___ | ___ | ___ |
| CMP-03 | ___ | ___ | ___ | ___ | ___ | ___ |
ISO 20816-1 includes general vibration magnitude and change concepts for operational monitoring and acceptance, but machine-family parts, manufacturer limits and the actual project basis may govern. It excludes torsional vibration and does not convert every shipboard casing reading into a universal acceptance limit. Confirm applicability before reporting conformity.
Escalate evidence when the verification does not close the question.
An elevated overall value can justify further work but does not name imbalance, misalignment, looseness, resonance or bearing damage. A narrow speed-sensitive response may require run-up or coast-down amplitude and phase. Repeated bearing or coupling distress may require alignment, soft-foot, pipe-strain, temperature, lubrication and load evidence. Impulsive high-frequency content may require suitable waveform or envelope processing plus inspection. A process-performance change may require pressure, flow, current or valve-state correlation.
| Finding | Confidence | Alternative cause | Next evidence | Operating action | Owner / due date | Closure test |
|---|---|---|---|---|---|---|
| FND-01 | ___ | ___ | ___ | ___ | ___ | ___ |
| FND-02 | ___ | ___ | ___ | ___ | ___ | ___ |
Distinguish confirmed mechanism, probable interpretation, correlation and unresolved observation. If vibration is transmitted into accommodation or structure, the next scope may be structural or habitability vibration rather than continued machinery-only measurement. If the change is torsional, shafting-specific methods and the approved calculation route are separate.
Release a conclusion that matches the evidence and acceptance route.
- Identify the machine train, work performed, measurement date and vessel condition.
- Attach point photographs or drawings, operating logs and acquisition settings.
- State the baseline source and every material comparability limitation.
- Keep measured values, diagnostic interpretation and acceptance statements separate.
- Name the criterion, revision and authorised acceptance owner where conformity is stated.
- Record anomalies, deferred runs, immediate restrictions and the next monitoring interval.
- Define the matched closure test for any corrective action.
| Report / revision | Evidence chain complete | Baseline suitable | Criterion confirmed | Open exceptions | Acceptance owner | Release status |
|---|---|---|---|---|---|---|
| RPT-___ | ___ | ___ | ___ | ___ | ___ | ___ |
These blank structures contain no vessel, customer, measured value, pass result, improvement percentage, approval, endorsement or completed-case claim.
Confirm the controlling revision for the actual machinery and project.
- ISO 17359:2018: general procedures for setting up condition-monitoring programmes; confirmed current by ISO in 2023.
- ISO 20816-1:2016: general machine-vibration measurement and evaluation guidance; current but expected to be replaced.
- ISO 13373-2:2016: processing, analysis and presentation of vibration data; its review closed on 3 September 2026.
- ISO 13379-1:2025: current general guidance on condition-monitoring data interpretation and diagnostic approaches.
These standards provide general technical context. The controlling maker instructions, machine-family standard, class rule, flag requirement, approved procedure and contract must be confirmed for the vessel. IACS does not approve service suppliers, and no class, flag, laboratory or maker authorisation is claimed.
Define the comparison before the post-work run.
Send the machinery details, overhaul report, point plan, previous data, target RPM/load, maker or project criterion, required witnesses and intended decision so the verification scope can be reviewed.
Request a machinery verification scopeUse the broader diagnostic evidence pack