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Conditions Of Use For Weld Neck Flanges
Weld neck flanges are suitable for piping systems with relatively low pressure levels, small pressure fluctuations, and less severe vibration and shock. The advantages of flat welding flanges with necks are that they are easier to align during welding and assembly, and they are relatively inexpensive, so they are widely used.
Sometimes for the sake of convenience, flat flanges with necks, flat flanges with necks and flat flanges are collectively referred to as flat flanges. This is included in the standards for chemical department flanges, national standard flanges, machinery department flanges, Japanese standard flanges, German standard flanges, American standard flanges and marine flanges. This consumption is larger in general pipelines in the domestic industry, and the pressure range is 0.25MPa ~ 4.0MPa.
As the name suggests, a flat-welded flange with a neck is a flange with a neck. Insert the pipe directly into the flange for welding. Usually, the inner diameter of the small-diameter flange is slightly larger than the inner diameter of the pipe by 1-1.5mm to leave such a margin, so it can be adjusted appropriately during the installation process. There are also large diameter flanges, because the flange diameter is large, so it is inconvenient to keep small.
The sealing surface of the flange with neck flat welding is usually divided into two types: one is called FF surface, that is, full-face flange. Let's say this flange is like a disc with a hole in the middle and then correspond to it, this is called a full flange.
There is also a sealing step. In layman's terms, there is a platform on the flange, called the waterline platform. Then use a lathe to form two or three water pipes into a line called a flat-raised flange. This waterline is used for sealing. Place the gasket in the middle of the two flanges and bolt to seal.
The following introduces the classification of flat welding flanges with necks:
1. According to chemical industry standards: integral flange (IF), threaded flange (Th), flat neck flange (PL), diameter butt welding flange (WN), neck flange (SO) , socket butt welding flange (SW), butt welding ring loose flange (PJ/E), flat welding ring loose flange (PJ/RJ), lining flange cover (BL(S)), flange Cover (BL).
2. According to the petrochemical industry standard, the neck flange can be divided into: threaded flange (PT), butt welding flange (WN), butt welding flange (SO), socket welding flange (SW), Large flange (LJ), flange cover.
3. According to the machinery industry standard, the flat welding flange with neck can be divided into: integral flange, butt welding flange, butt welding ring looper flange, flat welding ring looper flange, ring plate loose flange, method Lange.
Flat welding flange,Conditions of Use
There are four types of polishing methods for dual-phase steel flanges: manual, mechanical, chemical and electrochemical. The corrosion resistance and decoration of the flange can be improved by polishing. The existing stainless steel electropolishing solution still uses phosphoric acid and chromic anhydride. During the polishing and cleaning process, some chromium and phosphorus will be discharged into the waste water. pollution of the environment.
The shielding gas pressure of the butt welding flange is to avoid slight leakage of the butt welding flange. The shielding gas in the furnace should be connected to a certain positive pressure. Assuming that it is hydrogen shielding gas, it is generally required to be above 20kBar.
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