Spark test
Spark test turns up in 2 fields: geosynthetics, metallurgy. Here is what it means to the people in each one.
Spark test in geosynthetics
Holiday test for extrusion welds in which a high-voltage probe sparks through any gap to a buried conductive wire.
A copper or other conductive wire is laid under the overlap edge before the bead goes on; afterward a high-voltage probe is run along the seam, and a spark jumps wherever the bead has a hole. It is used where a vacuum box cannot seal, such as pipe boots, corners and steep details. The wire must be continuous and grounded for the test to mean anything.
"Lay the wire before you weld the boot, or there's no way to spark test it afterward."
Spark test in metallurgy
A rapid visual method for identifying ferrous alloys based on the sparks they produce.
A shop-floor identification technique where a piece of steel is pressed against a high-speed grinding wheel. The operator observes the color, shape, length, and branching pattern of the resulting spark stream to estimate the carbon content and identify alloying elements like tungsten or molybdenum.
"Do a quick spark test on that bar stock to make sure it's high carbon before we forge it."