Causes of damage:

1. The time for warming up the pipe is not enough after the glass pipe has been flushed and changed. 

2. The operating time is too long, and the quality of glass pipe is too poor. 

3. The screw is not fastened evenly. 

4. The steam pipe and water pipe are blocked. 

5. The mat is bad, water and steam leak from it. 

6. The water level gauge has not been rinsed  in accordance with the provisions, the water-draining is not seriously considered. 

The treatment of damage of water level gauge of steam drum: 

1. When the water level gauge of steam drum is damaged, immediately disconnect the damaged water level gauges, close the steam valve, water valve and open the water draining valve. Take measures to repair the damaged the water level gauges, monitor the water level with the other water level gauge of steam drum. 

2. When the in-situ water level gauge of steam drum is damaged, it is permitted to run for two hours if the following conditions are available. 

(1) The automatic regulator of feed water is reliable.

(2) The water-level alarm device is in good condition.

(3) The indication of electric contact water level gauge and the low-level water level gauge of steam drum is correct, and they have been compared with water level gauge of steam drum within 4 hours. 

(4) The evaporation capacity of boiler shall be kept stable. 

(5) If the automatic regulator and water-level alarm of feed water are not reliable, the indication of low-level water gauge of water drum is correct, then the water level gauge of steam drum is permitted to run 20 min. 

3. If all the water level gauges of steam drum are damaged and the operation of electric contact water level gauge and low-level water level gauge of steam drum is unreliable, the boiler shall be stopped immediately.