Lessons Learned

3 lessons from closed NCRs · searchable knowledge base

Recurring Defect Patterns Detected
Weld Defect — 2×Piping — 2×

These defect types have appeared multiple times. Review the lessons below before starting similar work.

3 lessons
NCR-2024-0007MV Shoft Kabir (Yard No. 078)Weld DefectMajor2024-11-20
Defect

Porosity cluster found in tank top butt weld (weld seam TT-H2-09) during radiographic examination. 4 pores in a 50mm length; max pore diameter 2.1mm. IRS Rules for Steel Ships (Part 2, Ch.13) limit: max pore diameter 1.5mm, max 3 pores per 50mm. Total affected seam length 320mm.

Lesson Learned

Radiographic examination of tank top butt welds must be performed before block erection. Pre-weld NDT checklist updated for Hold No. 2 and 3 blocks.

Action taken: Defective weld zone cut out by gouging. Weld joint re-prepared and back-gouged. Re-welded by Welder 2G qualified (WPS-SHOFT-TT-003). RT re-examination: 3 films cleared. IRS surveyor acceptance obtained.
NCR-2024-0001INS Vikrant (Yard No. 3001)Weld DefectMajor2024-10-13
Defect

Undercut defect on bracket-to-longitudinal fillet weld at Fr.115. Measured depth 1.4mm, exceeding IRS permissible limit of 0.5mm. Total affected weld length approx. 320mm.

Lesson Learned

Bracket-to-longitudinal welds at frames 110–120 in P-14 block require mandatory pre-heat due to plate thickness >20mm. Added to block pre-assembly checklist and WPS-CSL-007.

Action taken: Defective weld ground out to base metal. Re-welded with pre-heat 75°C as per WPS-CSL-007. Post-weld VT and UT inspection passed. IRS surveyor re-inspection completed.
NCR-2024-0005MT Bharat Gaurav (Yard No. 449)Hull PlateMajor2024-09-18
Defect

Keel plate distortion — max deviation 9.2mm over 2m length measured by straight edge. IRS flatness tolerance: 5mm/2m. Caused during block assembly due to inadequate support jig spacing.

Lesson Learned

Keel plate support jig must be spaced max 600mm for plates >14mm thickness. Pre-erection flatness check mandatory. Added to Procedure-LT-HULL-021.

Action taken: Flame straightening applied by certified operator. Thickness check by UT confirmed no reduction. BV surveyor re-inspection passed. Jig spacing increased to 600mm for future keel blocks.