V750 Vacuum Box

Bubble leak testing or vacuum box inspection of storage tank welds

The V750 vacuum box has been designed for the operators and to API 650/653 recommendations. Bubble leak (or vacuum box) testing is an integral part of tank inspections as required by the American Petroleum Institute (API) and other international standards associations to establish the condition of tank bottom plate welds and shell-to-bottom plate welds.


  • Designed to API 650/653 recommendations
  • 750 mm (29.53 in) weld inspection length, improves inspection times and reduces operator fatigue
  • Integrated LED lights provide the required light intensity as specified by API and ASME inspection standards
  • Screen glare and shadows from external light sources are eliminated
  • Calibrated vacuum relief valve ensures the correct vacuum is generated, too high a vacuum can damage the vacuum box and cause injury to the operator
  • Superior build quality with robust cast aluminum body
  • Two-stage seal design to improve initial vacuum, especially on large lap welds
  • Electric vacuum pump or compressor driven


More Efficient: Vacuum Box LEDs

The optional built-in LEDs provide the recommended light intensity along the weld under test by API 650. The internal LEDs eliminate the view window reflection that occurs when external lights are used to brighten the weld inspection area. You can easily turn the LEDs on and off, eliminating the need for you to move standard halogen floodlights as you move around the tank.

Better Accuracy: Calibrated Gauge

The V750 Vacuum Box comes with an industrial 50.8 mm (2 in) face pressure gauge rated to 762 mm (30 in) of mercury as required by ASME V Article 10–Bubble Test Vacuum Box Technique. The calibrated gauge offers the necessary confidence in your inspections by ensuring the proper recommended vacuum is generated.

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Safer and Quicker: Vacuum Relief Valve

Using a calibrated vacuum relief valve ensures the recommended vacuum under international standards. The advantage of such a valve is that once the necessary vacuum is achieved, the relief valve opens and maintains this vacuum, preventing it from damaging the vacuum box or injure the operator.

Electric Pump or Compressor Driven

The V750 generates a vacuum using an electric pump or an Air Vacuum Generator (AVG), and an external compressor. Inspection companies tend to use the electric pump because it is more flexible, while construction companies tend to use AVG systems.

High-pressure and Low-pressure Models

Vacuum boxes are rated to 20 in of Hg (10 psi/0.7 bar) recommended for in-services tanks or 10 in Hg (5 psi/0.4 bar) recommended for new tanks. V750 models are rated to 20 in of Hg, but if you are interested in a low-pressure model, review the V600LP and V400LP.


  • API 650/653 compliant
  • Optional integrated LEDs to maintain correct light levels and work alone
  • Higher productivity–Inspect 750 mm (29.5 in) long welds
  • Two-stage seal design to improve initial vacuum
  • Calibrated relief valve and vacuum gauge
  • Electric pump, compressor, or combination model

  • Flat and corner weld inspection models
  • More efficient
  • Reduce operator fatigue
  • Increase operator safety
  • Field-proven durability and reliability
  • User-replaceable seals



Dimensions (W × D × H)
  • 935 × 256 × 190 mm (36.8 × 10 × 7.5 in) LED model
  • 896 × 256 × 190 mm (35.3 × 10 × 7.5 in) non-LED model
  • 11 kg (24.2 lb)
Pressure rating
  • 508 mm of Hg (20 in of Hg)
Test weld test length
  • 750 mm (29.5 in)