Patent ID: 6939586

Claim:
A process for the continuous dip-coating of a metal strip ( 1 ) in a tank ( 11 ) containing a liquid metal bath ( 12 ), in which process the metal strip ( 1 ) is made to run continuously, in a protective atmosphere, through a duct ( 13 ), the lower part ( 13 a ) of which is immersed in the liquid metal bath ( 12 ) in order to define with the surface of the bath, and inside this duct ( 13 ), a liquid seal ( 14 ), the metal strip ( 1 ) is deflected around a deflector roller ( 15 ) placed in the metal bath ( 12 ), and the coated metal strip ( 1 ) is wiped on leaving the metal bath ( 12 ), characterised in that a natural flow of the liquid metal from the surface of the liquid seal ( 14 ) is set up in two overflow compartments ( 25 ; 29 ) made in the duct ( 13 ) and each having an internal wall ( 20 ; 26 ) which extends the duct ( 13 ) in its lower part and facing each side of the strip ( 1 ), an upper edge ( 21 ; 27 ) of each compartment ( 25 ; 29 ) is positioned below the surface, the drop in height of the liquid metal in the compartments ( 25 ; 29 ) is maintained greater than 50 mm in order to prevent metal oxide particles and intermetallic compound particles from rising as a countercurrent to the flow of liquid metal, the level of liquid metal in the compartments ( 25 ; 29 ) is maintained at a level below the surface of the liquid seal ( 14 ) by a pump ( 30 ) connected on a suction side to each of the compartments via a connecting pipe ( 31 ; 33 ) and provided on a delivery side with a pipe ( 32 ) for discharging withdrawn liquid metal into the volume of the bath ( 12 ), the level of liquid metal in each compartment ( 25 ; 29 ) is displayed by a display means formed by a reservoir ( 35 ) placed outside the duct ( 13 ) and connected to the base of each compartment ( 25 ; 29 ) via a connection pipe ( 36 ; 37 ), and the point where the pump ( 30 ) is connected to each compartment ( 25 ; 29 ) lies above the point where the reservoir ( 35 ) is connected to each compartment ( 25 ; 29 ).