What is the purpose of running a swab through each pipe length prior to welding?

What is the purpose of running a swab through each pipe length prior to welding?

• A. To remove loose dirt and mill scale
• B. To apply lubricant
• C. To check for cracks
• D. To cool the pipe

Answer: (A)

Cleaning the pipe ends before welding is essential to ensure a sound weld. Running a swab through each pipe length removes loose dirt and mill scale from the interior surfaces, which can otherwise become trapped in the weld root, causing porosity, inclusions, or weak fusion. By cleanly wiping away these contaminants, the welding heat can properly fuse the metal and produce a higher-quality joint. Lubricants would contaminate the weld with oil or grease, leading to defects. Checking for cracks requires non-destructive testing methods, not swabbing. Cooling the pipe isn’t the goal of swabbing, and it isn’t an effective way to manage heat during welding.

Cleaning the pipe ends before welding is essential to ensure a sound weld. Running a swab through each pipe length removes loose dirt and mill scale from the interior surfaces, which can otherwise become trapped in the weld root, causing porosity, inclusions, or weak fusion. By cleanly wiping away these contaminants, the welding heat can properly fuse the metal and produce a higher-quality joint.

Lubricants would contaminate the weld with oil or grease, leading to defects. Checking for cracks requires non-destructive testing methods, not swabbing. Cooling the pipe isn’t the goal of swabbing, and it isn’t an effective way to manage heat during welding.