Butt joint

From GAWDAwiki

Butt joint is a joint between two workpieces made in such a way that the weld joining the parts is between the surface planes of both pieces joined. ^[1]

Types of Butt Joints

A square butt joint is used primarily for metals that are 3/16 inch or less in thickness. The joint is reasonably strong, but its use is not recommended when the metals are subject to fatigue or impact loads.
A single-V butt joint is for use on plates 1/4 inch through 3/4 inch in thickness. Each member should be beveled so the included angle for the joint is approximately 60 degrees for plate and 75 degrees for pipe.
A double-V butt joint is an excellent joint for all load conditions. Its primary use is on metals thicker than 3/4 inch but can be used on thinner plate where strength is critical. Compared to the single-V joint, preparation time is greater, but less filler metal is used because of the narrower included angle.^[2]