For purposes of this subsection, "exhibitor boiler" shall mean a boiler which is operated in this state for nonprofit purposes including, but not limited to, exhibitions, fairs, parades, farm machinery shows, or any other event of a historical or educational nature. An exhibitor boiler includes steam locomotives, traction and portable steam engines, and stationary boilers of the firetube, watertube, model or miniature, and may be riveted, riveted and welded, or all welded construction, if used within the state for nonprofit purposes.
Okla. Stat. tit. 40, § 141.2