What are common reasons for welds failing during service and how could these be prevented in the fabrication stage?

• A. Welding defects cannot be prevented.
• B. Cracking, corrosion, and fatigue from poor design or process control; prevent with proper WPS, material selection, clean fabrication, NDT, and PWHT where required.
• C. Only appearance matters.
• D. Using more filler metal prevents all failures.

Answer: (B)

Weld failures in service are most often tied to cracking, corrosion, or fatigue that originate from design weaknesses or inadequate process control during fabrication. To prevent these problems up front, use a proper Welding Procedure Specification and select materials that are compatible with the expected service environment. Ensure the fabrication process includes thorough cleaning and fit-up, appropriate joint design to minimize stress concentrations, and careful control of heat input, preheat and interpass temperatures, and welding technique. Using materials with low hydrogen content and applying post-weld heat treatment when required helps relieve residual stresses and reduce cracking risk. Non-destructive testing during fabrication (visual checks, radiography, ultrasonics, magnetic particle, etc.) catches hidden defects before the part goes into service, allowing fixes before failure can occur. In addition, avoiding contamination and ensuring coatings or details don’t accelerate corrosion or weaken the weld area are important. In short, failures commonly come from design or process-control gaps, and preventing them starts with proper planning, material choice, cleanliness, controlled welding, and verification testing.