Technical | Design Considerations For Galvanizing

Coatings designed ot resist permanent marking by graffiti. Such coatings are easily cleaned using various cleaners without destroying the coating or its performance after cleaning. In powdercoating anti-graffiti coatings are available that can be cleaned using Citrus based non-polluting non-toxic cleaners.

Elgin 10.50m long, 1.10m wide and 2.50m deep.
Cumbernauld 7.0m long, 1.20m wide and 3.2m deep
All items are raised on a crane, tilted to an angle of approximately 30° before being dipped in molten zinc. It is possible to galvanize fabrications over 10 metres in length and up to approximately 3.4m high.
Contact us for specific details.

Galvanized articles can be joined by bolting (including friction grip connections), welding riveting and adhesive bonding. Welds should be constructed in such a way as to avoid acid traps (narrow crevices). All welds should be continuous if they are not enclosing an otherwise un-vented surface. Bolted joints are best made after galvanizing using galvanized fasteners.

If large flat contacting surfaces can not be avoided, the the edges of the contacting areas should be continuously welded and a hole drilled through both members to eliminate the danger of an explosion in the galvanizing bath.

The protection of thin edges by the coating system employed. Paint systems typicall have poor edge protection due to paint surface tension pulling liquid paint back from edges during curing. Galvanizing by contrast has better edge protection that away from the edges, ue to slightly thicker coating on edges. Powdercoating has an even coating thickness over edges. Edhes can be the weakest point for corrosion to start.

A physical test of a coatings performance, measured by allowing a measured weight to fall a measured distance under gravity to impact a sample plate. The result of the test is described by the damage the plate suffers from the impact.

Coating systems that replicate a beaten metal effect similar to that obtained by hammering sheetmetal with a ball pein hammer. Available in a variety of paint and powder systems, with well known brand names such as "Hammerite". Powdercoating can provide the same effect when specified, without the environmental effects that solvent based paints such as "Hammerite" involve.

Depending upon size and shape, articles for galvanizing may require suspension holes or lifting lugs. They may alternatively be handled by chains, or for smaller articles, on racks or in baskets.

Internal diaphragms and baffles should have cropped corners or edges.
Where hollow sections are internally vented an inspection hole will be required to allow the galvanizer to inspect the venting. The location of the inspection hole should be discussed with the galvanizer.

Water soluble paint or detachable metal labels can be used for temporary identification marks on fabrications. Enamel based paints or oil based markers should NOT be used. For permanent identification, to be legible after galvanizing, large heavily punched or welded marks are necessary.

If certain areas of steelwork need to remain uncoated this can sometimes be achieved by masking, but in our experience this is very unreliable. If this is an issue, call us in advance.

Clean steel surfaces are essential for good galvanizing.
Contamination in the form of grease, tar, paint and weld slag cannot be removed by chemical cleaning and may result in black bare spots after galvanizing.
Anti spatter weld sprays should be water-soluble to allow removal by the galvanizer during pretreatment stages.

On many sections of steelwork, provision must be made for venting and draining. Every sealed section of a fabrication must be vented for safety and to allow access and drainage of molten zinc, with holes diagonally opposite each other and as close as possible to the sealed end.
See the diagrams below

If you're still not sure, send us a sketch and we'll mark vent and drain holes for you, at no cost.

Galvanized articles can be joined by bolting (including friction grip connections), welding riveting and adhesive bonding. Welds should be constructed in such a way as to avoid acid traps (narrow crevices). All welds should be continuous if they are not enclosing an otherwise un-vented surface. Bolted joints are best made after galvanizing using galvanized fasteners.

If welding slag is not removed in the cleaning process it may result in black bare spots after hot dip galvanizing.

To avoid this problem, efforts should be made to use gas shielded welding processes e.g. M.I.G. and if coated electrodes are used, welds should be thoroughly de-slagged. In order to minimize the incidence of raised weld seams after galvanizing the silicon content of the welding rod material should be less than 0.04%.