The pressure of the protective gas for butt-welded flanges is to avoid slight leakage of the butt-welded flanges. The protective gas in the furnace should be connected with a certain positive pressure. Assuming that it is hydrogen protective gas, it is generally required to be above 20 kBar. Annealing air, butt-welded flanges generally use pure hydrogen as annealing air, with a purity of more than 99.99%. If the other part of the air is inert gas, the purity can be lower, but it cannot contain too much oxygen and water vapor.

　　Regardless of whether the internal annealing temperature of the butt-welded flange reaches the specified temperature, the butt-welded flange generally uses solid solution heat treatment, which is commonly known as "annealing", with a temperature range of 1040~1120℃. It can also be investigated through the inspection holes of the process annealing furnace. The butt-welded flange fittings in the annealing area should be incandescent, but not softened or sagging.

　　Handling water vapor in the casting furnace of butt-welded flanges. On the one hand, check whether the furnace body material is dry, and the furnace body material needs to be dried for the first time. On the other hand, check whether there is too much water stain on the butt-welded flange pipe fittings entering the furnace, especially those with holes in the butt-welded flange pipe fittings. Never leak water into them, otherwise the air in the furnace will be crushed.

　　Butt-welded flange furnace sealing. The butt-welded flange bright annealing furnace should be closed and isolated from the outside air; when hydrogen is used as the protective gas, one exhaust port is opened. The inspection method can use water to wipe the cracks of each joint of the annealing furnace to see if there is any leakage; the place where the gas leaks temporarily is the inlet and outlet of the annealing furnace. The sealing ring at this place wears out particularly quickly and needs to be checked and replaced frequently.