Advantages and production process of butt welding flange

Butt welding flange,also known as split flange, is a kind of flange. The flange is the part that makes the pipe and the pipe connect with each other, and is connected to the pipe end. There are holes in the flange, and the bolts make the two flanges tightly connected. Butt welding flange, gasket and fastener are collectively referred to as flange joint. Flange joint is a necessary component in equipment and parts, and also an essential part in piping design and pipe fitting valve.

ANSI B16.5 A105 RF forged slip on flanges

Butt welding flange is not easy to deform, well sealed and widely used. It is suitable for pipelines with great fluctuation of pressure or temperature or pipelines with high temperature, high pressure and low temperature. The advantage is that the price is relatively low, and the nominal pressure is not more than 2.5MPa. It is also used for pipelines with expensive, flammable and explosive media, and the nominal pressure is about PN16MPa. Butt welding flange connection is easy to use and can bear large pressure. And the materials of butt welding flange pad are different according to different levels of pressure. From low-pressure asbestos pad, high-pressure asbestos pad to metal pad.

Production and processing process of butt welding flange:

1.Whether the annealing temperature reaches the specified temperature. The butt welding flange is generally treated by solution heat treatment, which is commonly 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 area should be incandescent, but there is no softening and sagging.

2.Water vapor in the casting furnace for butt welding flange processing. On the one hand, check whether the furnace body material is dry. When the furnace is installed for the first time, the furnace body material must be dried; on the other hand, check whether there is too much water stain on the flange pipe fittings entering the furnace, especially if there is hole on the flange pipe fittings, do not leak in, otherwise the furnace atmosphere will be completely destroyed.

EN 1092-1 P250GH weld neck flanges

3.Tightness of furnace body. The butt welding flange bright annealing furnace shall 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 applied to the joints of the annealing furnace with soapy water to see if they run; the place where the gas is most likely to run 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, and it should be inspected and replaced frequently.

4. Protection gas pressure. In order to prevent micro leakage of butt welding flange, the protection gas in the furnace shall be kept at a certain positive pressure. If it is hydrogen protection gas, it is generally required to be more than 20kbar.

5.Annealing atmosphere. The butt welding flange generally uses pure hydrogen as the annealing atmosphere, and the purity of the atmosphere is better than 99.99%. If the other part of the atmosphere is inert gas, the purity can be a little lower, but it must not contain too much oxygen and water vapor.

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