Hot Dip Galvanizing
Formation of a coating of zinc and/or zinc alloys on iron and steel products by dipping in molton zinc
Quality standards as defined within ISO 1461:
When examined by normal corrected vision, significant surfaces shall be free from nodules, blisters, roughness, sharp points and uncoated areas.
The occurence of darker or lighter areas shall not give rise to rejection, nor shall wet storage staining providing minimum thicknesses are maintained
Coatings applied by hot dip galvanizing are designed to protect the materials from corrosion. The period of corrosion protection is proportional to the thickness of the coating.
Minimum coating thicknesses can be considered as:
Steel greater than 6mm thick - 70 microns
Steel 3mm to 6mm thick - 55 microns
Steel 1.5mm to 3mm thick - 45 microns
Steel less than 1.5mm thick - 35 microns
For centrifuged items, the minimum thickness can be considered as:
Greater than M20 - 45 microns
M6 to M20 - 35 microns
Less than M6 - 20 microns
Stress in the base material:
Some stresses in the base material will be relieved during the galvasnizing process and may cause deformation. Steel items that have been cold worked may become embrittled depending on the type of steel and degree of cold working.
Heat treated or cold worked steels may be tempered by the heat during the galvanizing process and lose some of their increased strength formed during heat treatment or cold working.
Hardened and/or high tensile steels may contain internal stresses of such a magnitude that pickling and hot dip galvanizing may increase the risk of cracking of the steel.
Quality standards as defined within ISO 1461:
When examined by normal corrected vision, significant surfaces shall be free from nodules, blisters, roughness, sharp points and uncoated areas.
The occurence of darker or lighter areas shall not give rise to rejection, nor shall wet storage staining providing minimum thicknesses are maintained
Coatings applied by hot dip galvanizing are designed to protect the materials from corrosion. The period of corrosion protection is proportional to the thickness of the coating.
Minimum coating thicknesses can be considered as:
Steel greater than 6mm thick - 70 microns
Steel 3mm to 6mm thick - 55 microns
Steel 1.5mm to 3mm thick - 45 microns
Steel less than 1.5mm thick - 35 microns
For centrifuged items, the minimum thickness can be considered as:
Greater than M20 - 45 microns
M6 to M20 - 35 microns
Less than M6 - 20 microns
Stress in the base material:
Some stresses in the base material will be relieved during the galvasnizing process and may cause deformation. Steel items that have been cold worked may become embrittled depending on the type of steel and degree of cold working.
Heat treated or cold worked steels may be tempered by the heat during the galvanizing process and lose some of their increased strength formed during heat treatment or cold working.
Hardened and/or high tensile steels may contain internal stresses of such a magnitude that pickling and hot dip galvanizing may increase the risk of cracking of the steel.