Ala. Code § 25-12-17

After 12 months for power boilers, 24 months for low pressure steam heating, hot water heating, and hot water supply boilers, and 36 months for pressure vessels following July 1, 2001, it shall be unlawful for any person, firm, partnership, or corporation to operate in this state a boiler or pressure vessel, except a pressure vessel covered by owner or user inspection service as provided for in Section 25-12-15, without a valid inspection certificate. The operation of a boiler or pressure vessel without the inspection certificate or at a pressure exceeding that specified in the inspection certificate or in violation this chapter shall constitute a misdemeanor.