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 with steam heating boilers 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 inspections, appeals, and licensing pursuant to chapter 135I.
  i.  Water heaters used for potable water if the capacity is less than or equal to one hundred twenty gallons, the burner input is less than or equal to two hundred thousand British thermal units, and the maximum allowable working pressure is less than one hundred sixty pounds per square inch.
  j.  An electric boiler with a water capacity of six gallons or less that is used as an integral part of an espresso coffee machine, cappuccino coffee machine, or cleaning machine.
  k.  Continuous coil-type hot water boilers used only for steam vapor cleaning, to which all of the following apply:
  (1)  The size of the tubing or pipe, with no drums or headers attached, does not exceed three-fourths of one inch in diameter.
  (2)  Nominal water capacity of the boiler does not exceed six gallons.
  (3)  Water temperature in the boiler does not exceed 350 degrees Fahrenheit.
  (4)  Steam is not generated within the coil.
  2.  Unfired steam pressure vessels not exceeding the following limitations are not required to be reported to the director 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.
  4.  An object shall not be considered under pressure and shall not be within the scope of this chapter when there is clear evidence that the manufacturer did not intend the object to be operated at more than three pounds per square inch and the object is operating at three pounds per square inch or less.
[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; 2013 Acts, ch 66, §2, 3, 5; 2014 Acts, ch 1026, §20; 2018 Acts, ch 1098, §2; 2023 Acts, ch 19, §57, 1791; 2023 Acts, ch 66, §18
Subsection 1, paragraphs d and h amended
Subsection 2, unnumbered paragraph 1 amended