The flat hinge-type bellows expansion joint consists of a reducer, bellows, and a pair of hinges connected to the reducer. The designed hinges and pins can withstand the thrust formed by internal and external pressure on the expansion joint. It can only absorb angular displacement in a single plane; to absorb displacement, two or three angular expansion joints should be used in combination.

Planar hinge-type bellows expansion joints are used in industries such as petrochemical, instrumentation, aerospace, chemical, power, cement, and metallurgy. Single hinge expansion joints for air-cooled vacuum conduits play an irreplaceable role in medium transportation, power line routing, machine tools, household appliances, and other fields.