What is the maximum groove angle allowed for a B-U9-GF joint?

The maximum groove angle for a B-U9-GF joint is indeed 45°. In the context of AWS D1.1, a B-U9-GF joint refers to a butt joint configuration that emphasizes the requirement for a certain groove preparation to ensure adequate weld penetration and strength. The specific angle of 45° is crucial as it balances the need for effective fusion of the base metals with the practical aspects of welding, such as accessibility and control of the heat input.

Specifying a maximum of 45° helps ensure that the weld can adequately fill the joint without creating issues such as insufficient penetration or complications in weld appearance. This angle is widely accepted and promotes effective weld quality in accordance with the standards set forth in the AWS D1.1 code.