Difference between Type A flanges and Type B flanges

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The differences between Type A flanges and Type B flanges are as follows: 1. Type A has a V-shaped groove, while Type B has a U-shaped groove; therefore, Type B is easier to weld through, resulting in higher strength and stiffness； Type B flanges have a short cylinder, which gives them better rigidity compared to Type A flanges; they can therefore be used in applications with higher pressures and larger diameters. 2. Type A flat-weld flanges are welded directly to the container; their weld seams are of small size or welding is carried out without beveling, which prevents the flange and the container from bearing forces together. The strength calculation for such flanges should follow the guidelines applicable to swivel flanges. Type A flat welding flanges should not be used in environments with flammable, explosive, or highly hazardous media, as well as in situations that require strict safety standards; they are also not suitable for use under conditions of intense cyclic loading ； Type B flat-face flanges generally come with a relatively thick short cylinder; the welding quality between the flange and this short cylinder is reliable, ensuring that both the flange and the container bear loads together. The strength calculation can be carried out as if it were a single integrated flange. Type B flat welding flanges are widely used in the connection of medium and low-pressure vessels and pipelines. 3. Type A flanges for steel pressure vessels are suitable for nominal pressures of 0.25–1.6 Mpa, with operating temperatures ranging from above -20 to 300 degrees Celsius℃ ； Type B flanges for steel pressure vessels are suitable for nominal pressures of 0.25–4.0 Mpa, and operating temperatures ranging from -20 to 350°C. Flange, also known as a flanged disc or rim. A flange is a component used to connect pipes to each other, serving for the connection between pipe ends ； There are also flanges used for the import and export of equipment, to connect two pieces of equipment together, such as reducer flanges. A flange connection or flange joint refers to a detachable connection that consists of a flange, gaskets, and bolts working together as a combined sealing structure. Pipe flanges refer to the flanges used for piping in pipe systems, while those used on equipment refer to the inlet and outlet flanges of the equipment. The flanges have holes, and bolts are used to hold the two flanges together. The flanges are sealed with gaskets. Flanges are divided into threaded flanges, welded flanges, and clip flanges. The main difference between Type B butt weld flanges and Type A butt weld flanges is that the flange ring has a short section attached to it. Flange rings are generally made of steel plates, but can also be made from forgings. During connection, the short section is welded to the cylinder or head, hence Type B flanges have good integrity, and their strength and stiffness are superior to those of Type A butt-welded flanges. In the current industry, butt weld flanges of type B have a wide pressure range, with a total of 6 pressure classes (PN0.25, 0.6, 1.0, 1.6, 2.5, 4.0 MPa). The applicable range of its nominal diameter is DN300–3000 mm, and the suitable operating temperature is –20°C–350°C.