Gate 6 Airstreams Renewables Practice Test

What should be done if there is a heavy coating of carbon on the weld due to contamination?

Oil and Grease on the Cable; Clean With Solvent Increase the Welding Current Use a Larger Disk Wipe the Mold With Water

Correct Answer:

Oil and Grease on the Cable; Clean With Solvent

Explanation:

Contamination from oil and grease on the welding components causes hydrocarbons to carbonize under heat, leaving a heavy carbon coating that can prevent proper fusion and create defects. The correct approach is to clean the surface with an appropriate solvent to dissolve and remove those hydrocarbons, then dry the area before welding. This ensures a clean, receptive surface for weld metal to wet evenly, improving weld integrity and reducing porosity or inclusions. Increasing the welding current won’t remove the carbon layer and can worsen defects, using a larger disk doesn’t address surface cleanliness, and wiping the mold with water would introduce moisture that can cause porosity or other issues.

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