(a) AS 18.60.180 — 18.60.390 do not apply to the following:

1. (1) boilers and unfired pressure vessels under federal regulation;
2. (2) unfired pressure vessels meeting the requirements of the federal Department of Transportation for shipment of liquids or gases under pressure;
3. (3) air tanks located on vehicles operating under the regulations of another state authority and used for carrying passengers or freight;
4. (4) air tanks installed on the right-of-way of railroads and used directly in the operation of trains;
5. (5) unfired pressure vessels having a volume of five cubic feet or less or vessels having an inside diameter not exceeding six inches;
6. (6) unfired pressure vessels designed for a pressure not exceeding 15 pounds per square inch when not located in a place of public assembly;
7. (7) manually fired miniature boilers for model locomotive, boat, tractor, or stationary engines constructed or maintained as a hobby for exhibition use, having a volume less than five cubic feet and grate area less than two square feet and equipped with an American Society of Mechanical Engineers coded safety valve of adequate capacity and size, a water level indicator, and pressure gauge;
8. (8) except as provided in (c) of this section, antique manually fired boilers of locomotive, boat, tractor, or stationary engines constructed or maintained as a hobby and equipped with an American Society of Mechanical Engineers coded safety valve of adequate capacity and size;

9. (9) automatic utility hot water heaters that are used for space heating using the potable system, if the hot water heater

   1. (A) is equipped with a safety relief valve and operational controls required by the latest American Society of Mechanical Engineers Boiler and Pressure Vessel Code published by the American Society of Mechanical Engineers that has been adopted by the Department of Labor and Workforce Development under AS 18.60.180;
   2. (B) contains only water;
   3. (C) does not exceed 120 gallons in capacity, a water temperature of 210 degrees Fahrenheit, a pressure of 150 pounds of square inch gauge pressure, or a heat input of more than 200,000 BTU an hour; and
   4. (D) contains a tempering valve that will regulate the outlet domestic water temperature at not more than 140 degrees Fahrenheit.

(b) The following boilers and unfired pressure vessels are exempt from the requirements of AS 18.60.320 — 18.60.360:

1. (1) boilers and unfired pressure vessels located on farms and used solely for agricultural purposes;
2. (2) steam and hot water heating boilers, used exclusively for heating purposes, that are located in private residences or in apartment houses of fewer than six families;
3. (3) unfired pressure vessels containing only cold water under pressure for domestic supply purposes, including those containing air, the compression of which serves only as a cushion or airlift pumping system;
4. (4) unfired pressure vessels containing liquified petroleum gas;

5. (5) unfired pressure vessels operating entirely full of water, and hot water supply boilers or domestic water heaters, if none of the following limitations is exceeded:

   1. (A) a heat input of 200,000 British thermal units per hour (57,143 watts);
   2. (B) a water temperature of 210 degrees Fahrenheit (99 degrees centigrade);
   3. (C) a maximum water-containing capacity of 120 gallons (454.2 liters);
6. (6) coil type boilers unless the water-containing capacity is six gallons (22.8 liters) or greater, the water temperature exceeds 350 degrees Fahrenheit (176.5 degrees centigrade), steam is generated in the coil, or the diameter of the tubing is greater than three-quarters of an inch (18.75 millimeters).