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In certain cases, fabricated assemblies may be liable to loss of shape when heated to galvanizing temperatures. This is due to the release of stresses induced during manufacture of the steel and in subsequent fabrication operations.
Following these simple recommendations will improve dimensional stability:
- Avoid designs which require double-end dipping to fit into the galvanizing bath. It is preferable to build assemblies and sub-assemblies in suitable modules so that they can be immersed quickly and fully in a single dip.
- Use symmetrical sections in preference to angles or channels
- Use sections of near equal thickness at joints
- Bend members to the largest acceptable radii
- Accurately preform parts to avoid force or restraint during joining
- Continuously weld joints, if possible using balanced welding techniques to reduce uneven thermal stresses. Balanced, staggered welding is permissible. For
- staggered welding of material of 3mm and lighter, weld centres should be closer than 100mm
- Large grey iron castings should always be normalised by the fabricator and then abrasive blast cleaned prior to galvanizing
Use of symmetrical sections minimises distortion during galvanizing. Avoid combinations of thick and thin materials.