There are 2 units of pay-off mandrel which allow the line to run continuously. The tail of 1 coil will be joined to the head of another coil by the facilitated welder. The entry looper (strip accumulator) allows the strip welding work to be carried out without stopping the process line.
Furnace Section
The oil on the strip is removed at the pre-heating zone, while iron oxide on the strip surface is removed at the direct fire zone before the full cycle of the annealing process is carried out at the radiant tube heating zone. The strip will then be cooled by air jet to a temperature which is compatible to the zinc bath temperature.
Zinc Coating
The annealed strip will then be immersed in a zinc bath to galvanise the coil with zinc. Air knives are used immediately after the zinc bath to ensure consistency of the zinc coating thickness and coverage. The coil will then be cooled by the air blower before passing through the water quench zone for further cooling.
Skin Pass, Leveller and Chemical Coating
The GI coil is put through the skin pass and leveller to ensure that the required surface finish and flatness are consistently achieved. The finished galvanised coil will be either coated with chromate or anti-rust oil, depending on the requirement of the customer, to prevent white rust formation.
Click below to view hot-dipped galvanized steel manufacturing process at full size.
