Galvanizing is a simple process of corrosion protection consisting of dipping steel into a bath of molten zinc to produce a non-oxidising zinc-iron alloy layer on the surface. It is probably the most economic, efficient and pollution-free process available to protect steel against corrosion.
The steel which has been cleaned of grease, paint and other contaminants, is immersed in the molten zinc which has been heated to around 450 degrees centigrade.
The zinc reacts with the surface of the steel to form a progressive and highly corrosion-resistant zinc-iron alloy coating. This is metallurgical bonded layer that becomes an integral part of the steel making it extremely resistant to physical damage and rusting.
The layers can actually be harder that mild steel, which gives the total coating a very tough and durable finish.
The standard galvanize coating can have a typical maintenance free life of up to 50 years in rural areas and up to 25 year in urban/marine areas.
The process is completed under the European Standard BS EN ISO 1461.
The Galvanizing Process we undertake at NK Coatings is described below…
Order ProcessingEach item is logged on the computer tracking system on arrival so it can be traced through each stage of the galvanizing process.
InspectionThe 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 ventingInadequately 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.
Hole SizesRemember, the larger the hole, the better the drainage, the better the finish.
Section Dimension Hole SizeUp to 50 mm 2 x 12 mm51 – 100 mm 2 x 16 mm101 – 150 mm 2 x 20 mm151 mm + 2 x 25 mm
Pre-treatmentThe 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.
The Process