Although there are a wide variety of braze joints to suit varying part and assembly geometries and functions, most braze joints are variations of one of two basic types – the butt joint and the lap joint.
- Butt Joint: To form a butt joint, the two pieces of metal are positioned in an edge to edge, in an end-to-end arrangement as shown in the figure. The strength of the bond depends to a large extent on the amount of bonding surface, but a properly formed butt joint will be strong enough to meet many application needs. The setup is relatively simple, and for some applications, it may be an advantage to have a consistent part thickness at the joint.
- Lap Joint: For applications which require a stronger bond, an alternative type of joint may be preferable. Lap joints have a larger bonding surface because the two metals overlap each other. Therefore a stronger bond is produced. Lap joints do have a double thickness in the joint area, which may be a potential problem for applications where space is restricted. But for plumbing fixtures and similar applications, this is not a problem. The overlapping nature of the lap joint actually assists in positioning the parts for brazing; particularly with tubular parts, the joint becomes self-supporting because one part fits into the other.
- Butt-Lap Joint: The advantages of both basic joint types are combined in a butt-lap joint. Although this type of joint requires more work to assemble, it has both a single thickness and maximum strength, and is usually self-supporting.