Suitable design and choice of steel for manufacturing components is of utmost importance for a correct galvanization. During design, it is very important to make the required drill holes in order to correctly fill and empty the parts, thus avoiding the formation of air pockets and zinc accumulation.
Cracks between sheets and overlapped surfaces are avoided. The edges of the inevitable overlaps are closed by welding, otherwise acid may penetrate between the contact surfaces, which would later damage the coating.
If it is not possible to avoid overlapped surfaces, a 6 mm diameter hole is made in each of the elements that form the overlap, for every 100 cm2 of overlapped area. A weld bead is then used to close the perimeter of the contact surface. The hole prevents zinc from possibly splashing during galvanization. It also prevents damaging the part.
Brackets and gussets welded onto pillars and beams, along with brackets on U-profiles, should have cut-out or perforated corners.
There should be at least one hole for filling and emptying, and another hole for breathing, located in the diagonally opposite end. Holes should have a minimum diameter of 50 mm. per each 0.53 m3 of volume.
Holes should be made with a minimum diameter of 13 mm, at the seat plates of the profiles and as near as possible to the lower angles.
Distortion can be avoided or minimized by:
Symmetric sections to avoid risk of distortion. Avoiding the combination of thick and thin materials.
In principle, all ferrous material can be galvanized, although the thickness and aspect of the coating achieved may be very different in each case. It is therefore recommended to consult the galvanizing company.
Manufacturing processes in which clean steel parts are combined with others of steel casting or rusted steel should first be cleaned by sandblasting before galvanization.
Weld slag should be eliminated before galvanization by stripping, grinding, sandblasting or with a pneumatic spray gun.
Materials that cannot be handled with chains, baskets, hooks or frames, should be provided with holes or grips for their suspension. Consult the galvanizing company in case of doubt.
Pipes should be assembled is the form of open mitre joints, as shown in “A”, or at least with interconnection holes with a minimum diameter of 20 mm., as shown in “B”. It is also necessary to make outer ventilation holes, as indicated in “C”, with a diameter equivalent to 25% of the inner diameter of the pipe, but never less than 10 mm.
There should be ventilation holes at the sides of the ends of each tubular section, or at least one per side in diagonally opposite positions. The size of the holes will depend on the type of profile and the construction method. It is therefore advised to consult the galvanizing company. As a rule of thumb, the section of holes may be set to 25% of the inner section of the profiles.