Steel tapes are used for corrugation of fiber optic cables to provide extra mechanical strength to the fiber optic cables that is required for some installation conditions. ECCS tape or Electrolytically Chrome Coated Steel tape or Stainless Steel tapes comes in rolls of 1 or 2 kilometers in length. But fiber optic cable lengths during production are usually in lengths of 2, 4 or 6 kilometers.
Production staff joints the steel tape by using Spot welding. Electric arcs generated by the spot-welding machine melts the metallic tape and makes joints. Spot welding is done at several points. There is a chance that these welding may fail while passing through the dies in corrugation unit or at the extrusion cross-head. Therefore it is necessary to make enough tests to ensure the tensile strength of such joints in advance. Samples shall be collected and tested before production to ensure that the joints of similar kind can pass through the dies without failure.
Tensile tests are conducted on a tensile test machine that is commonly used to test strength of plastic materials in a raw material laboratory.
Welded tapes shall possess at least 80% of the tensile strength of the Virgin tapes. So, before testing the strength of welded tapes, we need to test the strength of the virgin tapes. Collect samples of virgin tapes and welded tapes and conduct the tensile strength tests and record the values. If more than 90% of the welded samples have more than 80% of the tensile strength of virgin tapes, the we can say the welding process is pretty much reliable.
Some companies test the resistance of the welded tapes as well for reference.