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Hot dip galvanized flange nut manufacturer answers the reason for using flange nuts despite defects

  Hot dip galvanized flange nut manufacturer answers the reason for using flange nuts despite defects

  With the rapid development of electricity and transportation in China, it will inevitably promote the development of hot-dip galvanizing of flange nuts; Therefore, it is of great significance to develop automatic centrifugal pressure swing equipment, improve the hot-dip galvanizing process of fasteners, and improve the quality of hot-dip galvanizing coatings on fasteners. Hot dip galvanized fasteners have a thick coating, high bonding strength, and long-term corrosion, resulting in many defects in fasteners. It has always been highly valued in the power, communication, and transportation sectors. Below is an explanation of why defects occur in hot-dip galvanizing, but it is still popular:

  Difficulty in threading after plating; The remaining zinc adhered to the threads after hot-dip galvanizing is difficult to remove, and the thickness of the zinc layer is uneven, which affects the fit of the threads. GB/T13912-1992 Technical Requirements for Hot Dip Galvanized Coatings on Iron and Steel Products; GB/T13912-1992 General Technical Requirements for Electric Power Hardware; The external threads of fasteners must be machined or rolled according to the method specified in GB196 standard before or after hot dip plating, while the internal threads can be machined before and after hot dip plating. However, in practical applications, customers often require both internal and external threads to be galvanized, so people adopt various measures to solve the problem of hot-dip galvanizing of threaded fittings. For example, after coating threaded parts, back tapping; Leave a large fit gap; Centrifuge and other methods. The thread is prone to damage to the coating on some parts, even exposing the steel base, resulting in rust on the fasteners. Intentionally increasing the nut aperture beyond the range or leaving a fit gap can easily reduce the fit strength, but high-strength fits are not allowed.

  The high temperature of hot dip galvanizing operation will reduce the mechanical strength of high-strength flange nuts. After hot-dip galvanizing, the strength of some threads of Grade 8.8 bolts is lower than the standard requirements; After hot-dip galvanizing, the strength of bolts above grade 9.8 cannot meet the standard requirements. The working environment is harsh and heavily polluted. The hot dip galvanizing process for fasteners is carried out at high temperatures. The solvent drying in the zinc tank and the strong irritating hydrogen gas generated during the galvanizing process of the workpiece to be plated will cause the zinc tank to be exposed to high temperatures for a long time, resulting in the production of zinc vapor on the surface of the zinc tank. The entire working environment atmosphere is harsh.