Electroslag Welding (ESW) deposits the weld metal into the weld cavity between the two plates to be
joined. This space is enclosed by water cooled copper dams or shoes to prevent
molten slag from running off. The weld metal is produced from a filler wire that
forms an initial arc with the workpiece until a sufficient pool of liquid metal
is formed to use the electrical resistance of the molten slag.
This process requires special equipment used primarily for horizontal welds of very large plates up to 36 inches or more by welding them in one pass as in large machinery and nuclear reactor vessels.
There are also variations of ESW where shielding is provided by an appropriate gas and a continuous arc is used to provide weld metal. These are termed Electrogas Welding or EGW machines.
