Vacuum box testing detects through-thickness leaks in welds via pressure differential and bubble formation. Tove Leeds inspects tank bottom/shell welds, lap joints per API 650/653, EN 1593 where internal pressurization is impossible.

Procedure: clean surface, apply bubble solution, seal transparent box (15-20mm window), evacuate to ≥8 psi (0.55 bar), hold 10s, observe bubbles. Calibrated gauges, LED 500-15k lux, foam seals for curves.

Equipment: 400-750mm lengths, 5m+ diameters, relief valves. ASME V Art.10 App.II QC, 5-50°C temps.

Applications: tank construction/maintenance, ship hulls (IACS/LR), vessels (ASME BPVC), pipelines. Detects cracks/porosity rapidly, cost-effective vs alternatives, no scaffolding needed for compliance.