Protected type bange coupling

A protected type flange coupling is a rigid mechanical coupling used to connect two coaxial shafts for torque transmission, with an added safety feature to shield the bolts or nuts from damage and accidental contact. It consists of two flanges, each keyed to its respective shaft, and bolted together to form a solid connection. In the protected type, the bolt heads and nuts are recessed within the flange rims or covered by a protective circumferential flange extension. This “protection” prevents the bolts from projecting beyond the outer surface, reducing the risk of injury to operators, avoiding snagging on nearby components, and shielding the fasteners from mechanical damage during operation. The coupling transmits torque through the shear strength of the bolts and the key between each shaft and its flange. It is typically used in medium- to heavy-duty applications such as pumps, compressors, and industrial machinery where shafts are perfectly aligned and no flexibility is required. The protective design also improves durability in environments where exposed bolts might otherwise wear or corrode prematurely.