Designing Articles
Labelling and Marking
Water soluble paint or detachable metal labels can be used for temporary identification
marks on fabrications. Enamel based paints or oil based markers must not be used.
For permanent identification, to be legible after galvanizing, large heavily punched
or embossed marks are necessary.
Surface Contamination
Steel sections which have been cut or drilled using suds type oil can give similar
problems to burnt anti-spatter sprays. The cutting fluid which has been burnt or
baked onto steel should be removed prior to sending the steelwork for galvanizing.
Contamination is sometimes difficult to detect on the steel surface and will only
show up after the galvanizing treatment. The article may then have to be regalvanized,
at additional cost.
The presence of paint, oil and grease on a fabrication interferes with the galvanizing
process. All traces of surface contaminants must be removed before the process can
begin. This can result in time delays and extra charges being incurred.
If anti-spatter sprays are used, they will leave a residue on the steel which can
interfere with the galvanizing process. Anti-spatter sprays must be water soluble
so that any residues wash off in the pre-treatment process.
Tubular Venting
Every sealed section of a fabrication must be vented for reasons of safety and to
allow the access and drainage of molten zinc.
Each hole should be no more than 10mm from its respective sealed end. The vent hole
and drain hole must be at opposite ends of the section, diagonally opposite each
other.
Returns and elbows will require a vent hole – please consult with Premier Galvanizing.
Structural Steel
Bracers
Tip: This simple modification can:
- Improve the quality
- Save you money
- Speed up the process
- Ensure safety
Because the drain hole is half way up the end plate there will always be an amount
of zinc remaining in the tube, unable to drain out. This adds to the weight of the
component, for which you are charged and affects quality.
Stiffeners
External stiffeners should have the corners cropped to eliminate dead pockets. This will lead to
a cleaner and more blemish free finish.
Base plates
Hole sizes
Tip: The larger the hole size, the better the drainage, the better the finish. Drainage
and venting holes must be diagonally opposed.
| Tube diameter | Recommended Hole size |
| Up to 50mm | 1 x 12mm - both ends |
| 50 - 100mm | 2 x 16mm - both ends |
| 101 - 150mm | 2 x 20mm - both ends |
| 151mm+ | 2 x 25mm - both ends |
Warning! Inadequately vented fabrications may explode when immersed in molten zinc.
Channel Frames
External frame must have holes/crops on diagonally opposed corners (as above).
Any internal cross members must be cropped to allow free flow of zinc and ventilation
of any air pockets.
Holes or Notches
Holes or notches must be within 10mm of the sealed end of the section.
With hollow section fabrications, provision must be made for venting and draining.
On vertical members a drilled hole or "V" notch should be provided at each end of
the section. Each hole must be on opposite sides of the section.
Mesh
Tip: Due to expansion and contraction of the steel during the galvanizing process
– only weld every other wire in the mesh to minimise distortion.
Distortion
Distortion cannot be ruled out during the galvanizing process. Internal stresses
within a steel component and stresses introduced during fabrication will be relieved
in the molten zinc bath and may lead to distortion.
Also, steel of different thicknesses will expand and contract at different rates.
The greater the difference in steel thickness, the greater the chance of this leading
to distortion in fabricated steelwork particularly where large areas or long lengths
are joined.
Bath sizes
| Hull | Corby |
| 7.0m long x 1.2m wide x 3.2m deep | 7.6m long x 1.4m wide x 3.2m deep |