Fillet weld
Fillet welding refers to the process of joining two pieces of metal together when they are perpendicular or at an angle. These welds are commonly referred to as tee joints, which are two pieces of metal perpendicular to each other, or lap joints, which are two pieces of metal that overlap and are welded at the edges. The weld is triangular in shape and may have a concave, flat or convex surface depending on the welder's technique. Welders use fillet welds when connecting flanges to pipes and welding cross sections of infrastructure, and when bolts are not strong enough and will wear off easily. There are two main types of fillet weld: transverse fillet weld and parallel fillet weld. Aspects There are 5 pieces to each fillet weld known as the root, toe, face, leg and throat. The root of the weld is the part of deepest penetration which is the opposite angle of the hypotenuse. The toes of the weld are essentially the edges or the points of the hypotenuse. The face of the weld is the outer visual or hypotenuse that you see when looking at a fillet weld. The legs are the other two sides of the triangular fillet weld. The leg length is usually designated as the size of the weld. The throat of the weld is the distance from the center of the face to the root of the weld. Typically the depth of the throat should be at least as thick as the thickness of metal you are welding. Notation Fillet welding notation is important to recognize when reading technical drawings. The use of this notation tells the welder exactly what is expected by the fabricator. The symbol for a fillet weld is in the shape of a triangle. This triangle will lie either below a flat line or above it with an arrow coming off of the flat line pointing to a joint. The flat line is called "reference line". The side on which the triangle symbol is placed is important because it gives an indication which side of the joint is to be intersected by the weld. It is recognized that there are two different approaches in the global market to designate the arrow side and other side on drawings; a description of the two approaches is contained in International Standard ISO 2553, they are called "A-System" (which is more commonly used in Europe) and "B-System" (which is basically the ANSI/AWS system used in the US). In "A-System" two parallel lines are used as reference line: one is a continuous line, the other is a dashed line. In the "B-System", there is only one reference line, which is a continuous line. If there is a single reference line (B-System) and the triangle is positioned below the line, then the weld is going to be on the arrow side. If there is a single reference line ("B-System") and the triangle is positioned above the line, then the weld is going to be on