Section 4104.11 - Inspecting boilers(A) All power boilers and high pressure, high temperature water boilers and their appurtenances shall be thoroughly inspected internally and externally and under operating conditions at intervals of not more than one year, unless approved for biennial inspection under section 4104.13 of the Revised Code, and shall not be operated at pressures in excess of the safe working pressure stated in the certificate of operation mentioned in sections 4104.12, 4104.13, and 4104.15 of the Revised Code.(B) All low pressure boilers and their appurtenances shall be thoroughly inspected externally under operating conditions at intervals of not more than one year, and, except for cast-iron boilers, shall also be inspected internally at intervals of not more than three years, and shall not be operated at pressures in excess of the safe working pressure stated in the certificate of operation mentioned in sections 4104.12 and 4104.15 of the Revised Code.(C) All process boilers and their appurtenances shall be thoroughly inspected internally and externally and under operating conditions at intervals of not more than three years unless approved for quinquennial inspection under section 4104.13 of the Revised Code, and shall not be operated at pressures in excess of the safe working pressure stated in the certificate of operation mentioned in sections 4104.12, 4104.13, and 4104.15 of the Revised Code.Effective Date: 10/29/1995 .