Design Basics for Galvanizing

Here are some of the basic rules which should be used in design and fabrication.

  • You can galvanize all mild steels, some low alloy steels, cast iron and cast steel.
  • You can galvanize a wide variety of shapes and sizes and weights.  But consult your galvanizer if you have an unusual shape.
  • Follow the design guidance about vent holes in hollow sections.
  • Provide an additional clearance equal to 4x the coating thickness on threaded fasteners.
  • Provide about 1mm extra clearance on all matting surfaces.
  • Do not attempt to galvanize low melting point soldered joints.  They will collapse.
  • Do not use silicon - containing anti splatter paints.  The galvanizing will not "take" on these paints.
  • Remove moulding sand from castings by grit blasting.  Galvanizing will not "take" to sand.
  • Avoid overlapping surfaces if possible.  If you cannot avoid them, make sure you follow the venting guidance.
  • Remember the galvanizer must lift and turn your fabrication.  Make sure you provide lifting points for them to use.
  • Do not ask your galvanizer to galvanize fabrications which are very stiff in one plane but not in another.  They will almost certainly distort.
  • Avoid large unsupported areas of this gauge sheet.  They will probably distort.

The galvanizing reaction between zinc and steel takes place in liquid zinc, usually at 445-460°C.  At this temperature iron and zinc react quickly.  Typically the steel may be in the zinc for only a few minutes.  The fabrication is taken out of the zinc when the reaction is complete.  Although the zinc coating has already formed, its internal structure continues to change until the steel returns to normal temperature.

If in doubt

Most galvanziers have seen your problem before.  If you have any doubts about designing for galvanizing, talk to your galvanizer.  They can provide the most help.  A list of leading Australian galvanizers is available here.

If you prefer you can also talk to the technical staff at the Galvanizers Association of Australia.  If we cannot assist immediately we have access to all other technical expertise throughout the world.

Design for Hot-Dip Galvanizing

For a copy of the complete "Design Guide for Hot Dip Galvanizing - best practice for venting and draining" please click here to download a copy.