Any person subject to any order may file a written petition with the Secretary, stating that any such order or any provisions of such order or any obligations imposed in connection therewith is not in accordance with law and praying for a modification thereof or to be exempted therefrom. He shall thereupon be given an opportunity for a hearing upon such petition, in accordance with regulations made by the Secretary. After such hearing, the Secretary shall make a ruling upon the prayer of such petition which shall be final, if in accordance with law.