Section 408.4512. Miniature hobby locomotive boilers.

(1)  A   miniature  hobby   locomotive  boiler  is   designed  to be operated on a narrow gauge track of less than 24 inches.

(2)      At the initial inspection of a miniature hobby locomotive boiler, the owner shall provide the chief boiler inspector with design specifications and calculations for review and acceptance. If a boiler is approved for use, then the boiler division of the department shall issue an identifying state number and a deputy boiler inspector shall attach it to the boiler.

(3)       The owner shall ensure that a miniature hobby locomotive boiler has the following minimum equipment:

(a)     A pressure gauge graduated to approximately 1 ½ times the operating pressure, but not more than 4 times the operating pressure.

(b)     A means to extinguish the  fire  in  the firebox if   of    a    low water condition.

(c)      Two means of feeding water to the boiler, 1 of which  shall  be operable while the locomotive is stationary.

(d)      A water level gauge glass located so that the top of the bottom nut of the gauge glass is approximately 10% of the distance between the crown sheet and the shell, but not less than ½ inch above the crown sheet.

(e)      Two safety valves set at not more than  10%  above   the  operating pressure for boilers fabricated after the effective date of the rules. The capacity of the safety valves shall be  equal  to  or  greater  than  the calculated  steam generating capacity of the boiler.

(4)       The owner shall determine the maximum allowable working pressure of a miniature hobby locomotive   boiler  by  calculation.  In   place  of acceptable calculations,  the  owner  shall   subject  the    boiler   to     a hydrostatic   pressure test  of  1

½  times  the  owner  specified  operating pressure.

(5)            Triennially, during the certificate inspection, the  owner shall hydrostatically test the boiler to not more than  1  ½   times   the operating pressure.

(6)           The  boiler  division   of  the  department  shall   develop procedures, policies, and check lists necessary to accomplish the inspections

and tests required by these rules.

(7)       Repairs to miniature hobby locomotive boilers  are  exempt  from the licensing and permitting requirements of the act. Repair welding shall

be made in accordance with the requirements of ASME code section IX. Welding procedures and performance qualification shall be filed with the boiler division of the department for review.

History: 1998-2000 AACS; 2006 AACS.