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Visual Testing (VT)

The most fundamental — and most underestimated — of all NDT methods. When performed by a qualified inspector with the right tools, the right lighting, and the right knowledge of what to look for, visual testing is the first and most immediate line of defence for asset integrity.

What Is Visual Testing?


Visual Testing (VT) is the direct or aided observation of a component or structure by a qualified inspector to detect and evaluate surface conditions, dimensional compliance, and other visible features that indicate the presence of defects, damage, deterioration, or non-conformance. It is the oldest and most universally applied NDT method — required as a mandatory inspection step in virtually every major inspection code and welding standard.

The effectiveness of visual testing depends critically on three factors: the qualifications and experience of the inspector, the quality of lighting at the inspection surface, and access to the inspection area. Each of these is a managed parameter in our VT operations — not an afterthought.

Direct VT aids we deploy:

  • Calibrated illuminance meters — verifying minimum lighting levels per applicable code
  • Magnification lenses and loupes — for close-range surface evaluation 
  • Weld gauges and profile templates — for weld geometry assessment 
  • Mirrors and flexible inspection mirrors — for angled and restricted-access areas 
  • Pit depth gauges and surface comparators — for surface roughness and pitting depth assessment 

Where We Apply VT


  • Weld quality inspection during fabrication — at all required hold points
  • In-service condition assessment of pressure vessels, piping, and structural steelwork 
  • Marine structure and ship hull inspection during drydock 
  • Civil structure visual condition survey — bridges, jetties, and reinforced concrete structures
  • Pre-coating and post-coating inspection in corrosion protection programmes 
  • Dimensional verification of weld geometry (throat, leg, undercut, reinforcement) against specification
  • Post-incident visual assessment of damage extent and distribution  

Applicable Codes and Standards


  • ASME Section V — Article 9 (Visual Examination)
  • AWS D1.1 — Structural Welding Code — visual inspection requirements and acceptance criteria
  • EN ISO 17637 — Non-destructive testing of welds — Visual testing of fusion-welded joints 
  • API 510 — Pressure Vessel Inspection Code — external and internal visual inspection 
  • API 570 — Piping Inspection Code — visual inspection requirements 
  • API 653 — Tank inspection — visual inspection requirements