Hot dip coating employing a plug of chilled coating metal

A method for coating a continuous flat metal strip with a layer of coating metal, said method comprising the steps of:

• providing a vessel for containing a bath of molten coating metal;
• containing a bath of molten coating metal in said vessel, said bath having a top surface;
• providing a strip passage opening associated with said vessel, said opening being located below said top surface of the bath;
• moving a continuous flat metal strip along a path which extends through said strip passage opening and through said bath;
• coating said strip with a layer of said coating metal as the strip moves along said path;
• forming, from said bath, a plug which is composed of solidified coating metal, which surrounds said strip at a location downstream of said opening and which is substantially stationary relative to said strip;
• employing said plug to prevent the escape of molten coating metal from said bath through said opening while permitting said strip to move through said bath;
• chilling the coating metal within said vessel downstream of said opening to form and maintain said plug, employing said strip to chill the coating metal;
• and heating said molten metal bath at a location downstream of said plug by generating a time-varying magnetic field comprising a part which extends across said bath downstream of, and in contact with and adjacent to, said plug.