The Galvanizing Process we undertake at NK Coatings is described below…
Each item is logged on the computer tracking system on arrival so it can be traced through each stage of the galvanizing process.
The Quality team will check that material is properly prepared and vented .
Venting is vital to ensure high quality on all tubular and hollow section materials and more importantly to prevent an explosion when the steel is dipped into the hot zinc.
Important notes on venting
Inadequately vented materials can explode when immersed into the hot zinc.
Every sealed section of a tubular or hollow section fabrication MUST be vented for reasons of safety and drainage of molten zinc.
Vent holes or notches must be not more than 10 mm from the end of each sealed section and at opposite sides to provide maximum drainage.
Remember, the larger the hole, the better the drainage, the better the finish.
Section Dimension Hole Size
Up to 50 mm 2 x 12 mm
51 – 100 mm 2 x 16 mm
101 – 150 mm 2 x 20 mm
151 mm + 2 x 25 mm
The surface of the material must be free from grease, paint, weld-slag and other surface contaminants to achieve maximum surface bonding. This is achieved through our pickling or shotblasting process if necessary.
- Acid pickle removes surface oxides and mill scale.
- Preflux dip removes deeper oxides and prevents oxidation prior to zinc dip.
- Zinc immersion at approximately 450°C. This forms the zinc/zinc-iron alloy coating.
- The galvanized item is cooled in air or quenched in water.
- The material is then hand-finished to remove excess burrs.
- Thickness and surface condition inspections prior to delivery/collection.