Hot Dip Galvanizing

Daam Galvanizing is the expert in hot-dip galvanizing: a process that fully immerses and coats steel for protection that lasts in excess of 100 years. We’re meticulous in every stage of our process, working hard to provide you with the highest level of corrosion protection.

PROCESS:

Step 1: Inspection: When the steel arrives at our plant, it’s thoroughly inspected for size limitations, vent and drain holes and any additional work that may be required prior to galvanizing. It’s then transferred to the staging area to begin the cleaning process.

Step 2: Abrasive Blasting (if required): If there’s a shellac coating or paint on the steel, abrasive blasting must be done prior to cleaning. This is something that Daam Galvanizing can assist with.

Step 3: Cleaning: There are five processes the steel must go through — termed “pickling” — to prepare the steel’s surface for the metallurgical zinc-iron reaction.

  • Caustic cleaning to remove grease and oil, leaving only mill scale and rust.
  • Rinsing to remove residual caustic from the surface and to prevent acid tank contamination.
  • Acid cleaning to remove mill scale and rust to SSPC-SP8.
  • Rinsing to remove residual acid and iron from the surface and to prevent flux tank contamination.
  • Flux to protect the steel from oxidizing and to further clean it to a metallically bright surface. Flux allows for the proper metallurgical bonding of the zinc when galvanizing.

Step 4: Galvanizing: Steel is dipped into a molten zinc bath until it reaches the temperature of approximately 440°C. The zinc and the steel form zinc-iron alloys that are 75 – 300 microns thick depending on the thickness of the base steel. When the steel is removed from the bath, surface tension deposits an even layer of zinc on the ally layer. The zinc is thus metallurgically bonded to both the inside and outside of the base steel.

Step 5: Finishing: The steel is weighed and, depending on the end use, is finished to ensure there are no drips or sharp edges. Our Quality Control Manager performs a variety of simple physical tests to determine thickness, uniformity, adherence and appearance are in accordance with ASTM standards. The steel is then packaged for shipping and the customer is notified that their order is ready.