PURPOSE: To improve mechanical strength to cracks as well as to prevent a cavitation erosion by providing a coating layer of a Teflon material contacting closely along the circumferential surface of the inner surface of a thick metal material as a feeding passage of an alcohol fuel and the like.

CONSTITUTION: Along the circumferential surface of the inner surface 1' of a metal pipe body 1 of a stainless steel or the like, a coating layer 2 of a Teflon tube is provided, and its inner circumferential surface 2' is made as a flow passage surface 3. As a result, by the properties of antiswelling, elasticity, low friction coefficient, and the like of the Teflon material, the cavitation erosion in the flow passage surface can be prevented effectively for a long period, even though a diesel fuel, an alcohol fuel, and the like are used. Furthermore, the mechanical strength to cracks is also obtained sufficiently.