1. The indicator plate is firmly welded on the main beams and columns of boiler and the pointers are firmly welded on the expansion pieces vertically. The scale of the indicator plate is correct and clear, and red mark is painted on the datum of the plate. 

2. The pointer shall not be stuck or curved by external things, the pointer shall be perpendicular to the indicator panel face, the distance of the pointer with the indicator panel face is 3 ~ 5 mm.

3. When the boiler is in cold state, the pointer shall be in the benchmark of the indicator plate.