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What about threaded flanges without corrosion resistance?

2018-11-13 11:31:05   COMMENT:0 HITS:
  Threaded flanges are mostly used for pipeline transportation of chemical substances such as liquids and gases, and there are many corrosive media. Therefore, the requirements for threaded flanges are not only to maintain sealing and stability, but also to prevent corrosion of threaded flanges joints.

  In some gas transmission stations, the process pipelines and equipment are generally laid out in the open air and installed on the ground. Coatings of 3 Inch A182 F316L Forged Stainless Steel Threaded Flange are used to prevent corrosion. Good adhesion with metal surface, waterproof and atmospheric corrosion, anti-ultraviolet aging and good weather resistance are required. The coating composition of process pipeline is generally epoxy zinc-rich primer-epoxy mica iron rust-proof paint-fluorocarbon top coat. The total thickness of the coating should be greater than or equal to 320 Co M. According to the requirements of anti-corrosion construction specifications, the quality of anti-rust coatings is required to reach the level of Sa2.5 before painting.

  However, in the flange joints, especially in the clearance between groups of threaded flanges, it is difficult to clean grease and dirt on the surface and clearance of joints, and the quality of rust removal often fails to meet the requirements of the standard specifications, so the anti-rust coatings can not meet the requirements of the standard specifications. The coating is easy to fall off and can not play an anti-corrosion effect. The direct external cause of the corrosion of flange and bolt is the existence of corrosive medium between threaded flanges clearance. Without the protection of anticorrosive coating, the corrosion of threaded flanges metal surface and bolt will occur soon after contacting with water and air directly.

  Therefore, the threaded flanges must be corrosion-resistant in special occasions, which is conducive to maintaining the sealing of the threaded flanges.

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