1. Whether the annealing temperature reaches the specified temperature

　　Flange pipe fittings are generally treated by solution heat treatment, which is called "annealing", and the temperature range is 1040~1120℃ (Japanese standard). You can also observe through the observation hole of the annealing furnace. The flange pipe fittings in the annealing zone should be in an incandescent state, but there is no softening and sagging.

　　2. Furnace body tightness

　　The bright annealing furnace should be closed and isolated from the outside air; if hydrogen is used as the protective gas, only one exhaust port is open (used to ignite the discharged hydrogen). The inspection method can be wiped with soapy water on the joints of the annealing furnace to see if it is out of gas; the most easily out of place is the place where the annealing furnace enters the pipe and the place where the pipe exits. The sealing ring in this place is particularly easy to wear. Always check and change frequently.

　　3. Shielding gas pressure

　　In order to prevent micro-leakage, the protective gas in the furnace should maintain a certain positive pressure. If it is hydrogen protective gas, it is generally required to be above 20kBar.

　　4. Annealing atmosphere

　　Generally, pure hydrogen is used as the annealing atmosphere. The purity of the atmosphere is preferably above 99.99%. If the other part of the atmosphere is an inert gas, the purity can also be lower, but it must not contain too much oxygen and water vapor.

　　5. Water vapor in the furnace On the one hand, check whether the furnace body material is dry. When installing the furnace for the first time, the furnace body material must be dried; second, whether the flange pipe fittings entering the furnace have excessive water stains, especially if there are holes on the flange pipe fittings, do not leak water Go in, or else the atmosphere of the stove will be destroyed.