When the zinc pot is replaced or the zinc pot is stopped due to inspection, repair and other needs, the zinc liquid must be extracted from the zinc pot. The loss of the zinc pot is considerable once it stops operation, which will increase additional costs, and the zinc pot may be accidentally damaged. In order to avoid accidents, the whole process from stopping operation to reheating and temperature rising to resuming operation needs very good management.

1. Zinc extraction

After the zinc pot stops running, it is necessary to extract the zinc liquid from the zinc pot. The zinc liquid can be pumped into the spare large zinc ingot mold to cast large zinc ingots, which can reduce zinc oxidation and is easier to stack and transport. However, the weight of large zinc ingots shall not exceed the lifting capacity of the hot galvanizing workshop. Before extracting the zinc liquid, the following work must be done well: sufficient zinc ingot molds shall be provided and proper placement and demoulding positions shall be provided; Test run the zinc extraction pump; Before zinc extraction, cool the zinc solution to 440 ℃ or even lower, and carefully remove the zinc slag; After slag cleaning, reheat the zinc solution to 465~470 ℃, and then start zinc tapping. After the zinc liquid in the zinc pot is pumped out, the zinc pot can be naturally cooled or forced to cool by fan.

2. Detection of zinc pot

When testing the zinc pot, first visually inspect the inner wall of the pot to check the deformation, erosion pits or wavy damage of the zinc pot. Then the thickness of the pot wall is measured with an ultrasonic thickness gauge to determine the thinning of the pot wall and the severity of local erosion. According to the size of the pot and the thickness of the pot wall, a decision is made whether to replace the pot or to repair the pot by welding.

Carry out ultrasonic test, preferably after the zinc pot is cooled to room temperature; The iron zinc alloy layer on the boiler wall must be removed to expose the copper substrate on the boiler wall. Although ultrasonic thickness gauge can also be used to measure the thickness of the pot wall outside the pot when the zinc pot is filled with zinc liquid, it is difficult to test at all measuring grid points, so the situation of the whole zinc pot cannot be determined. It is an effective way for experienced personnel to probe the inner wall of the pot with steel hooks to find out the parts where the inner wall of the pot has been seriously eroded. In addition to checking the zinc pot, the entire combustion system (oil supply, gas supply, power, control and other equipment) should be checked and repaired at the same time.

3. Repair of zinc pot

The severely corroded parts or four pits of the zinc pot must be filled and welded. The filling and welding of zinc pot shall be carried out by skilled welders or manufacturers of zinc pot. Before filling and welding, the zinc and iron zinc alloy layers attached to the surface of the boiler wall must be removed, and the exposed clean surfaces must be polished and cleaned. The material of filler welding shall be the same as that of zinc pot. After filling welding, the filling welding area and its surroundings must be polished to be flush with other parts of the boiler wall.

4. The zinc pot is put back into use

In principle, the steps and operation methods of the inspected and repaired zinc pot or the old zinc pot that has been put into use for a period of time are identical with those of the new zinc pot. The old zinc pot must be cleaned before heating.

A large container for heating and thermal insulation has been introduced abroad, which can be used to store zinc liquid when inspecting zinc pots or replacing zinc pots. Each container can hold tens of tons of zinc liquid, and is also equipped with zinc pumps and pipelines. These equipment can be transported on an ordinary trailer and can easily provide services for hot-dip galvanizing enterprises. This can not only save time, save the trouble of casting zinc ingots and loading zinc ingots into zinc pots, but also significantly reduce the loss of zinc oxidation and energy consumption of heating and melting zinc, reducing costs. Of course, this kind of container can also be used together with the zinc ingot mold. After the inspection or replacement of the zinc pot, first put the zinc ingot into the bottom of the zinc pot, and then draw the zinc liquid in the container into the zinc pot. But at this time, be careful to avoid the flowing zinc liquid directly impacting the pot wall and bottom.