In which scenario is a welding inspector required to check the welder's certification?

A welding inspector is required to check the welder's certification before starting the weld to ensure that the welder is qualified and authorized to perform the specific type of welding being undertaken. This verification is crucial because it helps to confirm that the welder has the appropriate skills and has been trained to meet the requirements outlined in the AWS D1.1 code. Checking the certification beforehand prevents any potential issues that could arise during the welding process and ensures compliance with industry standards from the very beginning of the welding operation. This proactive approach helps maintain the integrity of the welding work and ensures that all regulations are followed before any welding activities commence, ultimately safeguarding the quality and safety of the completed structure.