Fettling
Fettling is a crucial finishing operation, predominantly used in the casting and foundry industries.
Fettling in the context of tube and pipe galvanizing is the essential final step of cleaning and dressing the article after it has been coated in the molten zinc bath.
Purpose in Galvanizing
While the core term originates from the foundry industry, its application here is specific to ensure the galvanized product is fit for immediate use and assembly. Fettling involves removing three primary imperfections:
- Drips and Icicles: Excess zinc that solidified into sharp points or drops, particularly at the ends or drainage holes of the pipe.
- Rough Edges: Any uneven, heavy deposits of zinc that formed during the withdrawal from the bath.
- Clinker or Dross: The zinc-iron alloy residue that can adhere to the surface.
This process, typically done by grinding, filing, or sanding, is critical for quality control. It guarantees a smooth surface, ensures fittings can be properly attached, and makes the pipe safe for handling, ultimately preventing delays and costs in the final construction phase.