AWS Welding Inspection and Testing Certification Practice Test

What is a common sign of wet or contaminated metal before welding?

1. Bright and shiny appearance

2. Presence of rust or oil

3. Absence of any defects

4. Uniform color

The correct answer is: Presence of rust or oil

The presence of rust or oil is indeed a common sign of wet or contaminated metal before welding. When preparing a metal surface for welding, it is crucial that the area is clean and free of any contaminants, as these can adversely affect the weld quality. Rust, which indicates oxidation, or oil, which may originate from handling or storage, creates barriers that can prevent proper fusion of the metals. If contaminants are present, they can lead to issues such as porosity, inclusions, or even weld failure, making it vital for welders to inspect metal surfaces for these signs prior to welding. Bright and shiny appearance might suggest that a surface is clean; however, it does not necessarily indicate the absence of contaminants like moisture or oil. Similarly, the absence of any defects does not provide enough information about the cleanliness of the metal surface, and uniform color alone does not guarantee that a surface is free from contaminants. Thus, the presence of rust or oil is a clear indicator that the metal may not be suitable for welding without proper cleaning and preparation.