What is the maximum size of a single pore allowed in a weld?

What is the maximum size of a single pore allowed in a weld?

• A. 2.5 mm
• B. 3.0 mm
• C. 4.0 mm
• D. 5.0 mm

Answer: (A)

Pores are gas pockets trapped in weld metal, and their size directly affects the weld’s ability to carry load and resist fatigue. In CSA W59, the acceptance criterion for a single pore allows a maximum size of 2.5 mm. This keeps any one defect from being large enough to act as a major stress concentrator, which could weaken the weld or lead to crack initiation under service loads. If you detect a pore larger than 2.5 mm, the weld would not meet the standard and would require repair or rejection. While several small pores might be considered under overall porosity limits, the single-pore size cap of 2.5 mm is the specific threshold for acceptance.

Pores are gas pockets trapped in weld metal, and their size directly affects the weld’s ability to carry load and resist fatigue. In CSA W59, the acceptance criterion for a single pore allows a maximum size of 2.5 mm. This keeps any one defect from being large enough to act as a major stress concentrator, which could weaken the weld or lead to crack initiation under service loads. If you detect a pore larger than 2.5 mm, the weld would not meet the standard and would require repair or rejection. While several small pores might be considered under overall porosity limits, the single-pore size cap of 2.5 mm is the specific threshold for acceptance.