4K SLAM inspection of a 980m production shaft avoids a 72-hour shutdown.

The operator main production shaft had last been fully inspected five years prior. Recent anomalies in the winder system and visual indicators from the cage had raised concern about conveyance and shaft wall integrity. A full manual inspection would have required the shaft to be taken out of service for at least 72 hours, with an estimated production loss running into the tens of millions of rand.

The client required three things. A complete, classifiable defect record of the shaft interior. An engineering recommendation on which defects required immediate action versus scheduled intervention. And a process that did not interrupt winder operation. Commercial pressure to avoid unplanned shutdown was high.

Conventional inspection methods were unsuitable. A traditional manual platform inspection would have extended the shutdown window significantly. Off-the-shelf scanning tools would have struggled with the GPS-denied environment, variable lighting, and loss of accuracy at depth. No commercial tool available at the time held accuracy over a full descent or handled classified defect reporting at shaft scale.

Delta Scan proposed a three-phase engagement built around a purpose-built shaft scanner and a new in-house tool, Shaft Analyser, developed for this class of problem.

Phase one was scoping. Our engineering team reviewed the original shaft drawings, recent maintenance logs, and the winder anomaly reports. We agreed the defect taxonomy (corrosion, deformation, fastening failure, concrete spalling, conveyance damage) and the severity grading (critical, moderate, advisory) with the client engineering team. A safety plan for shaft scanner deployment during active shaft use was signed by a registered engineer.

Phase two was capture. Over two operational days, the shaft scanner captured a full length descent and ascent of the shaft, logging LiDAR point cloud data and panoramic visual imagery. Capture was coordinated with the winder team so that the scanner operated in periods of reduced conveyance activity. Shaft Analyser reconstruction, developed specifically to hold accuracy over a long vertical descent, was applied in the field to validate capture quality before demobilisation.

Phase three was processing and reporting. The 3D reconstructed shaft model was segmented by Shaft Analyser into quadrants and depth bands. Defects were auto-detected against the agreed taxonomy, reviewed and reclassified by our engineering team, and located with sub-metre positional accuracy in the shaft frame of reference. The final deliverable was a Pr Eng signed audit report with per-severity bubble diagrams, a prioritised action schedule, and repair methodologies for each defect class.

• Capture system. Purpose-built shaft scanner (Delta Scan)
• Sensors. LiDAR and panoramic visual imaging
• Processing software. Shaft Analyser v1.0 (Delta Scan proprietary)
• Delivery environment. DeltaCloud
• Engineering review. Pr Eng signed audit report

• Day 0. Scoping, safety plan, defect taxonomy sign-off
• Day 1 to 2. On-site capture with the shaft scanner across full shaft length
• Day 3 to 5. Reconstruction, defect detection, engineering review
• Day 6. Final report delivery via DeltaCloud

The operator used the audit report to schedule the four critical-grade repairs into the next planned outage, consolidating what would otherwise have required an emergency shutdown. The moderate-grade defects were added to the shaft continuous monitoring register.

The Pr Eng certification on the audit was accepted by the operator insurance underwriter as basis for the shaft next renewal cycle. Shaft Analyser has subsequently been deployed on multiple operational shafts in the same group portfolio.