Genericized trade name for exothermic welding, in which a graphite mold is clamped over a cable end on a cleaned spot of pipe and a charge of copper oxide and aluminum powder is ignited to fuse the copper to the steel. It is the standard way to attach test leads, bond cables and anode leads, using a small charge on pressurized pipe to protect the wall. Every weld gets a hammer test and a coating cap before backfill.
Clean it to bright metal, cad weld the lead, give it a hammer tap and slap a coating cap on it.
Use only the charge size approved for the pipe's wall thickness and pressure. An oversized shot on thin-wall pipe can burn a hole in a live line.
Also heard as
- cadweld
- thermite weld
- exothermic weld
Related terms
Test station
Above-ground post or box with wires bonded to a buried structure, used to take CP readings.
Bond
Wire or cable connection that ties two metal structures together electrically, often to control CP current.
Holiday
Pinhole, void or bare spot in a coating that leaves the metal underneath exposed.