Surface Preparation for Hot Dip Galvanizing

The method of hot dip galvanizing may differ slightly from one galvanizer to another. But all the galvanizers have to go through the three basic steps of hot dip galvanizing are surface preparation, galvanizing and inspection.

Surface preparation is the most important step in the application of any coating. In most instances incorrect surface preparation is generally the cause of a coating failure before its expected service lifetime. The surface preparation step in the hot dip galvanizing process has its own quality control in that zinc simply are not reacting metallurgically with a steel surface which is not perfectly clean. Any failures in surface preparation will immediately be apparent when the steel is withdrawn from the molten zinc because the unclean areas will remain uncoated. The galvanizer has to take action to correct immediately. This can result in problems in coordinating activity that lead to costly and time-consuming delays, errors, and disputes concerning responsibility and financial liability.

Surface preparation for hot dip galvanizing typically consists of three steps: caustic cleaning, acid pickling and fluxing.

  • Caustic Cleaning – Dirt, paint markings, grease and oil from the metal surface are removed by a hot alkali solution. Epoxies, vinyl, blacktop or welding slag must be removed by sand-blasting, grit-blasting and other mechanical means before galvanizing.
  • Pickling – Scale and rust normally are removed from the steel surface by pickling in a dilute solution of hot sulfuric acid or ambient temperature hydrophobic acid. Surface preparation also can be accomplished using abrasive cleaning as an alternative to or in conjunction with chemical cleaning. Abrasive cleaning is a process whereby sand, metallic shot or grit is propelled against the steel material by air blasts or rapidly rotating wheels.
  • Fluxing – Fluxing is the final surface preparation step in the galvanizing process. Fluxing removes oxides and prevents further oxides from forming on the surface of the metal prior to galvanizing. The method for applying the flux depends upon whether the galvanizer uses the wet or dry hot dip galvanizing process.

Prashant Galvanizer has an experienced team of skilled worker for manufacturing Hot Dip Galvanizing plants. The Galvanizer who is famous in Gujarat as the Galvanizer consultant, provides consulting services to the engineering, galvanizing, and manufacturing industries regarding all phases of hot dip galvanizing.