Precision D-Patch Repair Following NDT Inspection

During a scheduled service and non-destructive testing (NDT) inspection, a defect was identified in the access ring of the boiler. Following the survey, the NDT inspector issued a detailed report, which allowed us to develop a comprehensive method statement and repair schedule for performing a D-patch repair.

The repair process was carried out systematically to ensure both safety and compliance with industry standards:

1. Defect Identification and Marking: Upon arriving on-site, the faulty area of the access ring was clearly marked for removal, ensuring precision and accuracy in repair work.
2. Material Removal: The defective section was cut out using an oxy-propane torch, creating a controlled opening for the new patch.
3. Surface Preparation: The cut edges underwent weld preparation, including beveling and cleaning, to ensure an optimal bonding surface.
4. Patch Fabrication: A custom patch was manufactured and accurately shaped to match the boiler’s curvature and dimensions.
5. Initial Fit-Up and Inspection: The patch was tack-welded in place and inspected to verify proper alignment and compliance with engineering standards before final welding.
6. Welding and Finishing: The patch was fully welded and the welds were ground smooth, creating a seamless finish that restores the boiler’s structural integrity.
7. Post-Repair NDT Testing: The repaired area was subjected to further NDT inspection to verify the quality and integrity of the weld.
8. Hydrostatic Testing: A hydro test was performed as the final stage of quality assurance, ensuring the boiler was fully safe and operational before sign-off.

This D-patch procedure not only restored the boiler’s integrity but also demonstrated the effectiveness of combining thorough inspection, precise fabrication, and rigorous testing protocols to extend the equipment’s operational life.