What is the purpose of post-weld cleaning and surface preparation after welding?

• A. To remove slag, scale, and contaminants, allowing for inspection, corrosion resistance, and proper surface finish.
• B. To seal the weld against moisture by applying protective coating only.
• C. To increase the hardness of the weld.
• D. To change the color of the weld bead.

Answer: (A)

Post-weld cleaning and surface preparation are about making the weld area clean of slag, flux, scale, spatter, and other contaminants so the weld can be inspected accurately, resist corrosion, and receive a proper surface finish. Removing these residues ensures nondestructive testing reflects the true weld quality, prevents corrosion cells from forming, and provides a smooth, uniform surface for coatings or paint to adhere. It also readies the heat-affected zone for any subsequent processing or testing. While applying a protective coating can be part of the final finish, the essential purpose is to remove residues and prepare the surface, not to change hardness or color.