Independent Inspection and No-Load Testing of Heavy-Duty Industrial Gear Units

Project at a glance

The inspection challenge

The equipment was at different stages of manufacture, making it necessary to verify different characteristics on different units. Certain dimensions were inaccessible on the completed unit because covers and couplings were installed. The inspector therefore used the unit on the test bench and partially assembled units for complementary dimensional checks. The assignment also required clear separation between witnessed testing and activities that the manufacturer had completed before the visit.

Scope of inspection

• Review of available inspection and test plan, drawings, inspection certificates and test documentation.

• Visual inspection of gearbox housings, shaft seals and accessible assemblies.

• Dimensional verification against the general arrangement drawing, including input/output shaft geometry.

• Witnessing of no-load clockwise and counter-clockwise operation, including an overspeed stage.

• Monitoring of operating speed, bearing temperatures, vibration and noise.

• Dry-film thickness (DFT) assessment of the painted unit and review of surface condition.

• Recording deviations and outstanding actions requiring clarification before final release.

Testing and technical verification

The witnessed no-load test included one hour in each direction at a rated input speed of 1,286 rpm, followed by an overspeed stage at 110% of rated speed. The report records a total running time of 165 minutes. The observed noise and vibration were assessed as acceptable, and no abnormal operating behavior or oil leakage at the shaft seals was reported.

The dimensional checks were reported satisfactory. The inspected coating thickness was satisfactory, and the accessible shaft seal areas showed no leakage during the witnessed run.

Findings and actions

The visit concluded “satisfactory with comments,” with no open nonconformities recorded. Two punch-list items remained open:

• 01

  Rated power discrepancy: the order/notification indicated 315 kW, while other values were discussed during the inspection. Confirmation against the applicable technical data sheet was required.

• 02

  Speed measurement calibration documentation: one of five recorded calibration values was outside the stated range; the discrepancy was referred for client information and possible supplier clarification.

Additional completion points included applying equipment tag numbers and verifying the final identification at a later inspection. The report notes that the air leak test and oil filling had already been performed by the manufacturer and were not witnessed; the oil level itself was not independently checked. Backstop components located at another facility were outside this visit’s inspection scope.

Why independent inspection matters

For industrial drive packages, even a small mismatch between equipment ratings, test records and purchase specifications can create uncertainty at installation or commissioning. Independent witness inspection gives project stakeholders a clearer view of equipment readiness, distinguishes directly observed results from manufacturer statements, and preserves a traceable list of unresolved items before release.

3BPSPP d.o.o. inspection capability

3BPSPP d.o.o. supports industrial projects through vendor inspection, manufacturing surveillance, mechanical testing witness, expediting and QA/QC documentation review. Our approach emphasizes independent reporting, practical verification against approved project requirements and prompt communication of deviations.

Independent inspection. Clear findings. Better project decisions.