Wisconsin

Sources disagree

More than one authority states this, and they do not state the same thing. Both are reproduced with the source each came from — deciding between them is yours, not ours.

Governing body

chardonlabs.com says governing body is Department of Safety and Professional Services' Division of Industry Services, as of 2026-08-05.

Division of Industry Services administers inspections under Wisconsin Administrative Code, SPS Chapter 341. Authorized inspector types: Wisconsin accepts insurance company inspectors and owner inspectors who hold Certificates of Competency issued by the department. Inspection frequency: High-pressure boilers require annual internal inspections, with external inspections accepted where internal access is not possible. Low-pressure boilers require external or internal inspections every 36 months.

https://www.chardonlabs.com/resources/commercial-boiler-inspection-regulations-by-state/

nationalboard.org says governing body is Department of Safety & Professional Services, Division of Industry Services, as of 2026-08-05.

One annual internal inspection. Where an internal inspection is not possible because of boiler construction, an external inspection will be acceptable. Should operating conditions require longer periods, an extension of time may be granted upon written application to the department with written concurrence of inspection agency. Low-pressure steam and hot-water boilers: one external or internal inspection every 36 months. Pressure vessels: one external or internal inspection every 36 months. Anhydrous ammonia storage and nurse tanks: one inspection every 36 months. Power piping: welder documentation and material inspection prior to start of fabrication (installed to ASME B31.1). INSURANCE INSPECTION REQUIREMENTS The department must be notified of suspension of insurance because of dangerous conditions . The department must be notified of new business or discontinuance of insurance . CERTIFICATE OF INSPECTION Certificate of Inspection is issued by the State of Wisconsin.

https://www.nationalboard.org/PrintAllSynopsis.aspx?Jurisdiction=Select

Statute citation

chardonlabs.com says statute citation is Wisconsin Administrative Code, SPS Chapter 341, as of 2026-08-05.

Division of Industry Services administers inspections under Wisconsin Administrative Code, SPS Chapter 341. Authorized inspector types: Wisconsin accepts insurance company inspectors and owner inspectors who hold Certificates of Competency issued by the department. Inspection frequency: High-pressure boilers require annual internal inspections, with external inspections accepted where internal access is not possible. Low-pressure boilers require external or internal inspections every 36 months.

https://www.chardonlabs.com/resources/commercial-boiler-inspection-regulations-by-state/

nationalboard.org says statute citation is Pursuant to S.101.17m the Department of Safety & Professional Services, Division of Industry Services, enforces Wisconsin Administrative Code, SPS Chapter 341, Boilers and Pressure Vessels ., as of 2026-08-05.

One annual internal inspection. Where an internal inspection is not possible because of boiler construction, an external inspection will be acceptable. Should operating conditions require longer periods, an extension of time may be granted upon written application to the department with written concurrence of inspection agency. Low-pressure steam and hot-water boilers: one external or internal inspection every 36 months. Pressure vessels: one external or internal inspection every 36 months. Anhydrous ammonia storage and nurse tanks: one inspection every 36 months. Power piping: welder documentation and material inspection prior to start of fabrication (installed to ASME B31.1). INSURANCE INSPECTION REQUIREMENTS The department must be notified of suspension of insurance because of dangerous conditions . The department must be notified of new business or discontinuance of insurance . CERTIFICATE OF INSPECTION Certificate of Inspection is issued by the State of Wisconsin.

https://www.nationalboard.org/PrintAllSynopsis.aspx?Jurisdiction=Select

Power boiler inspection interval

chardonlabs.com says power boiler inspection interval is annual internal inspections, with external inspections accepted where internal access is not possible, as of 2026-08-05.

Division of Industry Services administers inspections under Wisconsin Administrative Code, SPS Chapter 341. Authorized inspector types: Wisconsin accepts insurance company inspectors and owner inspectors who hold Certificates of Competency issued by the department. Inspection frequency: High-pressure boilers require annual internal inspections, with external inspections accepted where internal access is not possible. Low-pressure boilers require external or internal inspections every 36 months.

https://www.chardonlabs.com/resources/commercial-boiler-inspection-regulations-by-state/

nationalboard.org says power boiler inspection interval is One annual internal inspection, as of 2026-08-05.

One annual internal inspection. Where an internal inspection is not possible because of boiler construction, an external inspection will be acceptable. Should operating conditions require longer periods, an extension of time may be granted upon written application to the department with written concurrence of inspection agency. Low-pressure steam and hot-water boilers: one external or internal inspection every 36 months. Pressure vessels: one external or internal inspection every 36 months. Anhydrous ammonia storage and nurse tanks: one inspection every 36 months. Power piping: welder documentation and material inspection prior to start of fabrication (installed to ASME B31.1). INSURANCE INSPECTION REQUIREMENTS The department must be notified of suspension of insurance because of dangerous conditions . The department must be notified of new business or discontinuance of insurance . CERTIFICATE OF INSPECTION Certificate of Inspection is issued by the State of Wisconsin.

https://www.nationalboard.org/PrintAllSynopsis.aspx?Jurisdiction=Select

Low-pressure boiler inspection interval

chardonlabs.com says low-pressure boiler inspection interval is external or internal inspections every 36 months, as of 2026-08-05.

Division of Industry Services administers inspections under Wisconsin Administrative Code, SPS Chapter 341. Authorized inspector types: Wisconsin accepts insurance company inspectors and owner inspectors who hold Certificates of Competency issued by the department. Inspection frequency: High-pressure boilers require annual internal inspections, with external inspections accepted where internal access is not possible. Low-pressure boilers require external or internal inspections every 36 months.

https://www.chardonlabs.com/resources/commercial-boiler-inspection-regulations-by-state/

nationalboard.org says low-pressure boiler inspection interval is one external or internal inspection every 36 months, as of 2026-08-05.

One annual internal inspection. Where an internal inspection is not possible because of boiler construction, an external inspection will be acceptable. Should operating conditions require longer periods, an extension of time may be granted upon written application to the department with written concurrence of inspection agency. Low-pressure steam and hot-water boilers: one external or internal inspection every 36 months. Pressure vessels: one external or internal inspection every 36 months. Anhydrous ammonia storage and nurse tanks: one inspection every 36 months. Power piping: welder documentation and material inspection prior to start of fabrication (installed to ASME B31.1). INSURANCE INSPECTION REQUIREMENTS The department must be notified of suspension of insurance because of dangerous conditions . The department must be notified of new business or discontinuance of insurance . CERTIFICATE OF INSPECTION Certificate of Inspection is issued by the State of Wisconsin.

https://www.nationalboard.org/PrintAllSynopsis.aspx?Jurisdiction=Select

Accepted inspector types

chardonlabs.com says accepted inspector types is insurance company inspectors and owner inspectors who hold Certificates of Competency issued by the department, as of 2026-08-05.

Division of Industry Services administers inspections under Wisconsin Administrative Code, SPS Chapter 341. Authorized inspector types: Wisconsin accepts insurance company inspectors and owner inspectors who hold Certificates of Competency issued by the department. Inspection frequency: High-pressure boilers require annual internal inspections, with external inspections accepted where internal access is not possible. Low-pressure boilers require external or internal inspections every 36 months.

https://www.chardonlabs.com/resources/commercial-boiler-inspection-regulations-by-state/

nationalboard.org says accepted inspector types is Inspections made by inspectors employed by insurance companies and holding Certificates of Competency issued by the department are accepted in lieu of inspections made by a department inspector. Inspections made by inspectors employed by owners/users and holding Certificates of Competency issued by the department are accepted in lieu of inspections made by a department inspector., as of 2026-08-05.

One annual internal inspection. Where an internal inspection is not possible because of boiler construction, an external inspection will be acceptable. Should operating conditions require longer periods, an extension of time may be granted upon written application to the department with written concurrence of inspection agency. Low-pressure steam and hot-water boilers: one external or internal inspection every 36 months. Pressure vessels: one external or internal inspection every 36 months. Anhydrous ammonia storage and nurse tanks: one inspection every 36 months. Power piping: welder documentation and material inspection prior to start of fabrication (installed to ASME B31.1). INSURANCE INSPECTION REQUIREMENTS The department must be notified of suspension of insurance because of dangerous conditions . The department must be notified of new business or discontinuance of insurance . CERTIFICATE OF INSPECTION Certificate of Inspection is issued by the State of Wisconsin.

https://www.nationalboard.org/PrintAllSynopsis.aspx?Jurisdiction=Select