Lead-acid batteries for heavy applications are today made with tubular plates throughout Europe and in many parts of the world. The performances of the tubular plates are definitely superior to those of flat plate cells in terms of life. The plates are contained in a sheath of polyester fiber, permeable to electrolytes, with the seam corresponding to each tube. The tightness of the seam is crucial: any defect would cause a short circuit and irreparably damage the battery.
The sheath produced is unrolled, slid under a backlight system and rewound: high speed 2D stitching control detects automatically any interruptions, thickness, distance. The photo shows a defect in the seam number 6.
This technology is not just limited to the thickness measurement of tanks, but it is also used in the on-line measurement of multilayer pipes, typically fuel hoses.