Ohio Rev. Code § 715.18
Any municipal corporation may establish and furnish the necessary equipment for a department of purchase, construction, and repair. Such department shall be under the management of the director of public service, who shall purchase all material, supplies, tools, machinery, and equipment, and shall supervise all construction, alterations, and repairs in each of the municipal departments whether established by law or ordinance.
No such purchase, construction, alteration, or repair shall be made except upon requisition by the director, the officer at the head of the department for which it is to be made or done, or upon the order of the legislative authority of the municipal corporation, nor shall any purchase, construction, alteration, or repair for any of such departments be made or done except on authority of the legislative authority and under sections 735.05 to 735.09 of the Revised Code, if the cost thereof exceeds the amount specified in section 9.17 of the Revised Code.
R.C. § 715.18