Requirements for zinc coatings
The zinc coating of the product shall meet requirements of the EN ISO 1461 Standard "Zinc coatings applied onto steel using a hot galvanizing process (elementary zinc coating) - Requirements and testing (ISO 1461 : 1991)".
Appearance of the coating on products that meets requirements for elementary zinc coating:
A surface of the coating to be continuous and free of damages that may decrease product's value in use.
Since the products are badly designed due to the zinc coating process, ash and residuals of fluxes may occur and their removal to be agreed between parties.
In case of elements welded discontinuously or spot welded as well as in case of superposition of surfaces the leakage of etching fluids, causing the rust sagging on the zinc coating at joints, are possible to occur. Creation of the acid gaps shall be avoided and eliminated at the design stage.
Since profiles are cold-shaped, the line beads can occur, but it doesn't reduces the anticorrosive features of the coating.
Risers at places of zinc leakages are acceptable.
Zinc sharp icicles and frills on the wire nets aren't acceptable. These damages shall be eliminated by The Hot Galvanizing Plant.
White tarnish (white rust) on the coating isn't a damage and subject to lay a claim.
In case of using the steel with a silicon content out of permissible levels, the zinc coating may be thicker and its adherence to the basis metal can be reduced or can not occur.
In case of using the steel with a silica content out of a permissible levels, a reaction: iron - zinc can run very fast and the coating, as a whole can consist of alloy layers. Such coating can be very rough and grey and during weathering this color can turn into brown one.
The Hot Galvanizing Plant isn't obliged to straighten those of elements that have been bended by reason of releasing the internal stresses.
The Hot Galvanizing Plant isn't obliged to patent and calibrate holes and threads.
In case of inhomogeneity of an external surface of the product (chemical constitution, surface structure, impurities that can not be eliminated during the chemical treatment) the appearance of zinc coating of one product can be inhomogeneous, too.
In case of special requirements due to the appearance or thickness of the coatings, they shall be agreed in written with The Hot Galvanizing Plant.
In case of "hollow" constructions (inaccessible cavity constructions), a/m requirements don't apply to internal surfaces, but to external ones, only.
Caution: Roughness on the surface of the basis metal (steel) such, as rolling slag pits, grooves, cavities in backs of welds, corrosion pits, laps, delaminations, welding seams are visible after the hot galvanizing process and, more, they sometimes become to be visible, as not before.
Coating thickness
Please find the values of minimum thickness of the zinc coating in the Table No. 2. Its upper limit isn't restricted unless it reduces a possibility of product's application (its functionality).
In case of special requirements due to the thickness of the coatings, they shall be agreed in written with The Hot Galvanizing Plant.
Coating adherence
The coating shall be flexible and well bounded to the basis metal to withstand a loading connected with a normal exploitation of the hot galvanized products. In case of products to be loaded more strongly, particular agreements due to relevant materials and shapes shall be made.
