Metal bellows duct expansion joints are utilized to compensate for thermal expansion in many industrial gas systems when the quality, security, and fire resistance of a metal expansion joint is desirable instead of rubber duct expansion joints, or fabric duct expansion joints.

The metal duct expansion joints are available in round or rectangular configurations, and in flanged, weld, or collar ends.  The flanges are usually 3/8" thick angle flanges, but plate flanges can be used if needed. The weld ends are 1/4" thick and 3" wide, and are designed to butt weld to duct.  The collar ends are 1/4" thick and 2" wide, and are designed to slip over duct and connect with a fillet weld.

Standard designs are shown in the submittal sheets, but many other designs are possible, including accessories of liners and covers.