Butt-welded flanges, four factors that affect the process of the flange are: whether the annealing temperature reaches the regular temperature. Flange treatment generally adopts solution heat treatment, and the temperature scale is 1040~1120℃. You can also investigate through the annealing furnace. The flange in the annealing zone should be in an incandescent state, but there is no softening and sagging.
Furnace body tightness. The bright annealing furnace should be closed and isolated from the outside air; if hydrogen is used as the maintenance gas, only one exhaust port is open (used to ignite the discharged hydrogen). The method of inspection can be wiped with soapy water on the joints of the annealing furnace to see if it is out of gas.
The simple outgassing area during the period is the area where the annealing furnace enters the pipe and the area where the pipe exits. The sealing ring in this area is particularly easy to wear and needs to be checked and replaced frequently. The flange maintains air pressure. In order to avoid micro-leakage of pipe fittings, the maintenance gas in the furnace should maintain a certain positive pressure. If it is hydrogen maintenance gas, it is generally required to be above 20kBar.
Annealing atmosphere. Generally, pure hydrogen is used as the annealing atmosphere, and the purity of the atmosphere is above 99.99%. If the other part of the atmosphere is an inert gas, the purity can be lower, but it must not contain too much oxygen and water vapor.