Boiler Inspections

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This page presents information from various sources on boiler inspections as it relates to the Live Steam hobby.

State by State Synopsis

This document provides a state-by-state synopsis of boiler rules and requirements. Search for the terms "hobby" and "miniature".

National Board Synopsis of Boiler and Pressure Vessel Laws, Rules and Regulations

Marty Knox writes:

You can look up the boiler rules in effect where you live. Go to and click on Juridictions. You then select Canada or USA, then your province or state. When you click on Details it opens up a window , usually with a picture of your Chief Inspector and a link to their website. Most of these websites will have the Law or Rules and Regulations. Some of them will have an index, if they do you can quickly see if there is a section on hobby or miniature boilers. Others you will need to wade through the Law or rules to see what it says.
A word of caution - you want to be careful if you do talk to an inspector. In some cases the boiler division has chosen to ignore the hobby - you don't want to do anything that will make them take official notice of the hobby.It may be wise to speak to your local club or other hobbyists rather than an inspector.

Marty adds:

Illinois, New York, and Texas have exemptions for Hobby boilers below a certain size. Maryland, Michigan, and Washington have rules that require inspection of hobby boilers but do not require an ASME stamped vessel.


Mark Knox wrote June 2017:

Here in Michigan you can run at any pressure you can show your boiler is safe at. One of my locomotives was approved for 235 PSI, but I ran it at 125PSI.


See "Pennsylvania Boiler Code Requirements",


Mark Knox wrote June 2017:

The Hobby Boiler rule for Texas is an exemption. I was on the advisory committee to the Texas Board of Boiler Rules working on rules for hobby boilers when Fred Springer contacted a legislator. He was able to get a bill passed to amend the law and grant the exemption. This took place back in the late 1980's and early 1990's. I left Texas in January of 1990; it was sometime after that the law was passed.
The Law states that the following boilers are exempt - 3) manually fired miniature boilers that:
(A) are constructed or maintained for locomotives, boats, tractors, or stationary engines only as a hobby for exhibition, recreation, education, or historical purposes and not for commercial use;
(B) have an inside diameter of 12 inches or less or a grate area of two square feet or less; and
(C) are equipped with a safety valve of adequate size, a water level indicator, and a pressure gauge;
Pressure is not a factor.
ASME code for miniature boilers has a 100 PSI limit. The ASME is a construction code; each jurisdiction(which is usually a state) decides what rules they want to follow.



Washington State Boiler Code declares that a hydro pressure test more than 200% of Maximum Allowed Working Pressure (MAWP) results in a damaged pressure vessel. This causes the State to downgrade the MAWP.

Club Inspection Policies and Procedures

Pre-Purchase Inspection

See Also