How is the size of an equal leg fillet weld determined?

The determination of the size of an equal leg fillet weld is fundamentally based on the leg length of the largest equal leg triangle that can be formed between the two pieces being joined. In the case of equal leg fillet welds, the two legs are of equal length and are positioned perpendicular to one another.

The size is typically referenced as the length of these legs, which dictates how much material is present in the weld joint. A fillet weld essentially resembles the shape of a right triangle, where the legs represent the sides of the triangle that meet at the right angle. Understanding this triangular relationship is crucial when it comes to assessing the strength and suitability of the weld for the specific application.

While other measures, such as throat thickness or the overall length of the weld, are important for different aspects of weld design and performance, they do not directly describe the size of the weld in the context of equal leg fillet welds as clearly as the leg length does. Therefore, the determination of size is accurately represented by the leg length of the largest equal leg triangle involved in the weld.