Except as provided in this chapter, it is unlawful for any officer, employee or agent of the city to order the purchase of supplies or equipment or make any contract in violation of this chapter, and any purchase ordered or made, or contract made contrary to the provisions of this chapter shall not be approved by any officer or employee of the city and the city shall not be obligated by any such purchase or contract made in violation of the provisions of this chapter. (Ord. 429 §1 (Exh. 1), 1999).