This vacuum box is designed for leak testing of internal corner welds that cover three sides with 90° geometry – typical of “internal 3×90°” edges. It is specialized for use in containers, vats and sumps where the welds extend up three surfaces. The box provides an efficient and safe means of testing tightness in complex corner constructions.

Key features and benefits

• Designed for testing inner corner edge welds (inner 3×90° edge seams) that are otherwise difficult to access with standard vacuum boxes.

• Compact length – the standard version has an edge length of approximately 3 × 270 mm for the three corners, which provides good coverage without excess size.

• Also available in a miniature version for pools/tubs with a low height (approx. 40 mm), so that testing can take place even if the side or area is limited.

• Includes adapter for reduction when the height of the tub is low – provides flexibility and makes the box compatible with different situations.

• Transparent inspection glass (sight glass) and soft sealing strip so you can monitor bubble formation under vacuum – essential for seeing leaks.

Technical specifications

• Edge length: approx. 3 × 270 mm for the standard version.

• Miniature version: edge lengths of approximately 3 × 60 mm for inner corners in low-height tubs.

• Design: wooden retro corner (inner 3×90°), adapted to cover three surfaces that meet at a corner.

• Glass inspection/Sealing: highly transparent polycarbonate “sight glass” + soft rubber strip for good sealing.

• Adapter: included in the box for reduction in case of limited height.

• Length dimension: standard “economic length” for such vacuum boxes is in the range of 500-750 mm for many types; this type of 3×90° boxes follows similar guidelines.

Areas of application

• Inspection and leak testing of internal corner welds in tanks, collection vessels and similar structures where the weld covers three sides.

• Especially useful for tubs with limited height or where 90° corners are formed between the floor and side walls.

• Maintenance and inspection programs for hazardous liquids, where regulations such as the German “GefStoffVO” require documented leak testing of fillet welds.

• Use in industrial environments, in the workshop or in the field, where quick and visual confirmation of tightness in corner welds is desired.