What is the prohibited size for fillet welds according to the AWS D1.1 code?

The AWS D1.1 Structural Welding Code stipulates that when it comes to fillet welds, a size of 3/16 inch is not permitted for certain applications. This is due to the code's provisions regarding the thickness of the base metals being welded. Specifically, the code sets limitations on the size of fillet welds in relation to the thickness of the materials being joined to ensure that welds can develop the necessary strength without defect and maintain adherence to sound welding practices.

In cases where base metal thickness exceeds minimum limits, larger fillet weld sizes may be necessary, but smaller welds can be insufficient under certain conditions, such as fatigue or stress concentrations. Thus, the use of a fillet weld size at or above 3/16 inch could create a situation that does not comply with the guidelines meant to optimize weld performance and integrity.

Consequently, understanding these parameters helps ensure that welds are designed effectively for their intended load requirements, promoting the overall safety and reliability of welded structures.