89.4  Exemptions.
  1.  The provisions of this chapter shall not apply to the following boilers:
  a.  Boilers of railway locomotives subject to federal inspection.
  b.  Boilers operated and regularly inspected by railway companies operating in interstate commerce.
  c.  Boilers under the jurisdiction and subject to inspection by the United States government.
  d.  Steam heating boilers and unfired steam pressure vessels associated therewith and mobile power boilers used exclusively for agricultural purposes.
  e.  Heating boilers in residences.
  f.  Fire engine boilers brought into the state for temporary use in times of emergency.
  g.  Low pressure heating boilers used in buildings other than those for public assembly.
  h.  Hot water heating boilers used for heating pools or spas regulated by the department of public health pursuant to chapter 135I.
  i.  Water heaters used for potable water if the capacity is less than or equal to fifty gallons, the burner input is less than or equal to fifty thousand British thermal units, and the maximum allowable working pressure is less than one hundred sixty pounds per square inch.
  2.  Unfired steam pressure vessels not exceeding the following limitations are not required to be reported to the commissioner and shall be exempt from regular inspection under provisions of this chapter:
  a.  A vessel not greater than five cubic feet in volume and not having a pressure greater than two hundred fifty pounds per square inch.
  b.  A vessel not greater than one and one-half cubic feet in volume with no limit on pressure.
  3.  Jacketed direct or indirect fired vessels built and installed in accordance with the American society of mechanical engineers code, section VIII, division 1, appendix 19, shall not be considered boilers or power boilers for purposes of this chapter and shall not be required to meet the American society of mechanical engineers standard for controls and safety devices for automatically fired boilers. However, jacketed direct or indirect fired vessels as described in this subsection shall be subject to inspection under section 89.3 as pressure vessels.
[C46, 50, 54, 58, 62, 66, 71, 73, 75, 77, §89.3; C79, 81, §89.4]
92 Acts, ch 1098, §4; 98 Acts, ch 1222, §21, 28; 2005 Acts, ch 47, §1; 2007 Acts, ch 135, §4; 2010 Acts, ch 1015, §4