Non-standard flanges are those connected to containers or pipes by fillet welding. It can be any flange. Check integral flange or looper flange according to the integrity of flange ring and straight segment. Flange ring has two types: neck and non-neck. Compared with the neck butt flange, non-standard flange is simple in structure and saves material, but its rigidity and sealing performance are not as good as that of the neck butt flange. Non-standard flanges are widely used for connecting medium and low pressure vessels and pipelines.
Non-standard flange is suitable for low pressure grade, pressure fluctuation, vibration and impact is not too serious pipeline system. Non-standard flanges are widely used because they are easier to align during welding and assembly and are relatively inexpensive.

Non-standard flanges are rings made of materials that can produce plastic deformation and have a certain strength. Most gaskets are cut from non-metallic sheets or manufactured in proportion by a professional factory. Is asbestos rubber board, asbestos board, polyethylene board and so on. It is also a metal filler gasket made of asbestos and other non-metallic materials wrapped by a thin metal plate (iron sheet, stainless steel); Another type of gasket is made of thin steel tape and asbestos tape wound together. General rubber gasket is suitable for the occasion of temperature below 120℃; Rubber gasket is suitable for steam temperature below 450℃, oil temperature below 350℃, low pressure occasions. In the case of 5MPa below, acid resistant asbestos plate is usually used for corrosion medium.
In high pressure equipment and piping, metallic gaskets of lens-type or other shapes made of copper, aluminum, 10 steel and stainless steel are used. Non-standard flange gasket and sealing face contact width is very narrow (line contact), sealing face and gasket processing completion degree is high.
In addition, non-standard flanges can prevent surface rusting and cracking. Usually non-standard flange surface will be electroplated (yellow zinc, white zinc, etc.), or coated with anti-rust oil, spray anti-rust paint.