# Maine — US boiler and pressure vessel inspection requirements by state For Maine, governing body is Boiler and Pressure Vessel Safety Program, Office of Professional and Occupational Regulation; statute citation is Maine Revised Statutes, Title 32. Professions and Occupations, Chapter 131. Boilers and Pressure Vessels, Sections 15101 through 15121; power boiler inspection interval is One annual internal certificate inspection; One annual external inspection, in operation, approximately six months from the certificate inspection; low-pressure boiler inspection interval is Low pressure steam heating boilers located in schoolhouses: one annual certificate inspection, which shall be an internal inspection every third year, with an external or internal inspection at the discretion of the inspector on the two intervening years. Low pressure hot-water supply boilers located in schoolhouses: one annual certificate inspection, which shall be an internal inspection where possible, every third year. Low pressure hot-water heating boilers located in schoolhouses: one annual certificate inspection, which shall be an internal inspection every third year, with an external inspection during the two intervening years; pressure vessel inspection interval is Initial inspection shall be an external safety inspection; Renewal certificate inspections are completed once every 3 years and it shall be an internal where construction permits, recorded from its source on 2026-08-05. - **State:** Maine - **Governing body:** Boiler and Pressure Vessel Safety Program, Office of Professional and Occupational Regulation - **Statute citation:** Maine Revised Statutes, Title 32. Professions and Occupations, Chapter 131. Boilers and Pressure Vessels, Sections 15101 through 15121. - **Power boiler inspection interval:** One annual internal certificate inspection; One annual external inspection, in operation, approximately six months from the certificate inspection. _(verified: appears in the quote below)_ - **Low-pressure boiler inspection interval:** Low pressure steam heating boilers located in schoolhouses: one annual certificate inspection, which shall be an internal inspection every third year, with an external or internal inspection at the discretion of the inspector on the two intervening years. Low pressure hot-water supply boilers located in schoolhouses: one annual certificate inspection, which shall be an internal inspection where possible, every third year. Low pressure hot-water heating boilers located in schoolhouses: one annual certificate inspection, which shall be an internal inspection every third year, with an external inspection during the two intervening years. _(verified: appears in the quote below)_ - **Pressure vessel inspection interval:** Initial inspection shall be an external safety inspection; Renewal certificate inspections are completed once every 3 years and it shall be an internal where construction permits. _(verified: appears in the quote below)_ - **Accepted inspector types:** Inspections made by inspectors employed by insurance companies and licensed by the Boiler and Pressure Vessel Safety Program are accepted in lieu of inspections made by a department inspector. - **Exemptions:** Boilers and pressure vessels under federal control. Boilers and pressure vessels used for agricultural purposes only. Boilers used solely for propelling motor road vehicles. Boilers of steam fire engines brought into the state for temporary use in times of emergency to check conflagrations. Low pressure steam heating boilers, hot water heating boilers, and hot-water supply boilers, except those located in schoolhouses or those used as process boilers. Pressure vessels used for the transportation and storage of compressed or liquefied gases when constructed in compliance with specifications of the US Department of Transportation. Pressure vessels located in private residences and apartment buildings with fewer than six apartments. Pressure vessels having an internal or external operating pressure not exceeding 15 psi. ## What the source says > High-pressure boilers: One annual internal certificate inspection; One annual external inspection, in operation, approximately six months from the certificate inspection. Miniature boilers: One annual certificate inspection; One biennial internal inspection. Cast-iron boilers: one annual certificate inspection while unit is in operation. Low pressure steam heating boilers located in schoolhouses: one annual certificate inspection, which shall be an internal inspection every third year, with an external or internal inspection at the discretion of the inspector on the two intervening years. Low pressure hot-water supply boilers located in schoolhouses: one annual certificate inspection, which shall be an internal inspection where possible, every third year, with an external or internal inspection at the discretion of the inspector during the two intervening years. Low pressure hot-water heating boilers located in schoolhouses: one annual certificate inspection, which shall be an internal inspection every third year, with an external inspection during the two intervening years. Low pressure process boilers: one annual certificate inspection, which shall be an internal inspection every third year, with an external inspection during the two intervening years at the discretion of the inspector. Pressure vessels: Initial inspection shall be an external safety inspection; Renewal certificate inspections are completed once every 3 years and it shall be an internal where construction permits. In the event, that an internal inspection is not feasible, the inspector must use an alternative method of determining material thickness for the shell and/or head. ## Source - https://www.nationalboard.org/PrintAllSynopsis.aspx?Jurisdiction=Select Last verified: 2026-08-05. Review by: 2027-08-05. Part of [US boiler and pressure vessel inspection requirements by state](https://referencesource.org/boiler-inspection-requirements-by-state/).