There are a number of factors to consider when selecting a joint design:

• The strength and hermetic requirements of the joint in service
• The fabrication techniques of the components
• The quantity of assemblies to be brazed
• The assembly method of the components, including filler alloy application
• The brazing process selected

The brazed joint should have sufficient strength to meet the service requirements of the parts. The effect of joint clearance on braze joint tensile strength is dramatic. With proper joint clearance the joint strength will approach that of the base material. With excessive clearance the joint strength approaches the strength of the filler metal.

There are two basic joint designs; the butt joint and the lap joint.

Braze joints should be given the same design considerations as any other joint. Cross sections that move the stress concentrations away from the joint edges and into the base metal should always be used in highly stressed parts.


Doublers can be added to butt joints,


or the joints maybe scarfed,


and butt-lap joints offer the advantages of both lap and butt joints.



Lap joints:

• An overlap of three to four times the material thickness of the thinner material being joined is recommended to maximize strength.
• A joint gap of 0.002 inch interference fit to 0.008 inch gap depending upon the filler metal.
• For specific joint gap recommendations for a particular filler material click here.

Butt joints:

• Butt joint area should be maximized to maximize strength.
• Joint strength is at its maximum with a joint clearance of approximately 0.001 inch.