A bracket includes a cylindrical portion and a plate-shaped portion that are integrally formed. The cylindrical portion is provided at one end side of a blank along one direction and is provided with a slit extending over an entire length of the cylindrical portion in the one direction as a result of forming a portion at the one end side of the blank along the one direction into a cylindrical shape extending in the one direction. The plate-shaped portion is provided at the other end side of the blank along the one direction. The cylindrical portion of the bracket is inserted in the cylindrical body member formed of an aluminum alloy material, and the body member and the cylindrical portion are clinched by electromagnetic tube compression.

Two adjacent pipe flanges are secured by a plurality of clamp units, where each clamp unit, in order to receive the adjacent flanges in its receptacle, is thermally expanded.