1. The WN flange connection should be kept on the same axis, the center deviation of the bolt hole should not exceed 5% of the hole diameter, and the bolt should be free to perforate. The connecting bolts of the flange should have the same specifications, the installation direction should be the same, and the bolts should be tightened symmetrically and evenly. More skills and knowledge can be found on the WeChat public account: Construction Hydropower Knowledge Platform.

　　2. Diagonal washers of different thicknesses should not be used to compensate for the non-parallelism of WN flanges. Do not use double washers. When the large diameter gasket needs to be spliced, it should not be butted with the flat port, but should be in the form of a diagonal lap or labyrinth.

　　3. In order to facilitate the installation and disassembly of the WN flange, the fastening bolts and the surface of the WN flange shall not be less than 200 mm.

　　4. When tightening the bolts, it should be symmetrical and intersecting to ensure uniform stress on the washer.

　　5. Bolts and nuts should be coated with molybdenum disulfide, graphite oil or graphite powder for subsequent removal: stainless steel, alloy steel bolts and nuts; piping design temperature below 100°C or 0°C; open air facilities; atmospheric corrosion or corrosive media .

　　6. Before the WN flange is installed, metal gaskets such as copper, aluminum and mild steel should be annealed.

　　7. It is not allowed to directly bury the WN flange connection. Flange connections of buried pipelines shall have inspection wells. If it must be buried, anti-corrosion measures should be taken.