What's the meaning of duct flange specification L20*4?
The L20*4 you said should be flange free. The flange height of the air duct shall be referenced to the provisions of the metal flange duct, that is, the flat steel of 20*4
The ventilation pipe is generally made in 15- meters, 2 meters between the ends of the flange, the wind pipe connection needs flange and flange connection, do not allow welding. Flange thickness between 3-5 mm.Wind pipe flange specification L20*4 is equal angle steel 20x20x4 flange.
Just equal angles, 20x20x4 flanges.
Angle steel classification and specifications: mainly divided into equilateral angle steel and unequal angle steel two categories, in which unequal angle steel can be divided into non equilateral, thick and unequal, unequal thickness of two kinds. The specification is expressed by length and angle of edge thickness size. At present, the domestic angle specifications for 2 - 20 cm, to length number number, the same horn steel often have 2 - 7 different edge thickness. Imported steel angles indicate the actual sizes and edges of both sides and indicate the relevant standards. Generally, the length of 12.5cm is larger than that of angle steel, and between 12.5cm and 5cm is medium angle steel. The angle of 5cm is smaller than that of angle steel. Inlet and outlet angle steel orders to use commonly required in the specification, the steel is carbon steel steel corresponding. That is, angles, apart from specification numbers, do not have specific components and performance sets. The delivery length of angle iron is divided into two kinds: the length and the ruler, and the length of the fixed angle of the made angle iron is four to 3, 9m, 4 - 12M, 4 - 19m and 6 - 19m. The length of Japanese steel angle is chosen from 6 to 15m.Wind pipe flange specification L20*4 is equal angle steel 20x20x4 flangeThe habit of writing equal angles is L*X*, L20*4 is 20x20x4 equal angles, and 4 is the thickness of the angle flanges,See the GB/T9787 angle standard
