Hawaii Administrative Rules › Title 12 - DEPARTMENT OF LABOR AND INDUSTRIAL RELATIONS › Subtitle 8 - HAWAII OCCUPATIONAL SAFETY AND HEALTH DIVISION › Part 10 - BOILER AND PRESSURE VESSEL › Chapter 223.1 - HEATING BOILERS - STEAM HEATING BOILERS, HOT-WATER HEATING BOILERS, HOT-WATER SUPPLY BOILERS, AND POTABLE WATER HEATERS › Section 12-223.1-10 - Acceptable installation of pressure relief valves for steam heating, hot-water heating, hot-water supply boilers

Current through June,
				  2024
The following shall apply to the installation of pressure
					 relief valves for steam heating, hot-water heating, and hot-water supply
					 boilers:
(1) Pressure relief valves
				  shall be located at the top side of the boiler. The top side of the boiler
				  shall mean the highest practicable part of the boiler proper but in no case
				  shall the safety valves be located below the normal operating level and in no
				  case shall the pressure relief valve be located below the lowest permissible
				  water level. They shall be connected directly to a tapped or flanged opening in
				  the boiler, to a fitting connected to the boiler by a short nipple, to a
				  Y-base, or to a valveless header connecting steam or water outlets on the same
				  boiler. Coil or header type heating boilers shall have the pressure relief
				  valve located on the steam or hot-water outlet end. Pressure relief valves
				  shall be installed with their spindles vertical. The opening or connection
				  between the boiler and any pressure relief valve shall have at least the area
				  of the valve inlet;
(2) When a
				  boiler is fitted with two or more pressure relief valves on one connection,
				  this connection shall have a cross-sectional area not less than the combined
				  areas of inlet connections of all the pressure relief valves with which it
				  connects;
(3) When a Y-base is
				  used, the inlet area shall be not less than the combined outlet areas. When the
				  size of the boiler requires a pressure relief valve larger than NPS 4, two or
				  more valves having the required combined capacity shall be used. When two or
				  more valves are used on a boiler, they may be single, directly attached, or
				  installed on a Y-base;
(4) A
				  threaded connection may be used for attaching a valve;
(5) Pressure relief valves shall not be
				  connected to an internal pipe in the boiler;
(6) No shutoff valve of any description shall
				  be placed between the pressure relief valve and the boiler or on discharge
				  pipes between such valves and the atmosphere;
(7) A discharge pipe shall be used. It shall
				  be not less than the nominal size of the valve outlet. Where multiple valves
				  relieve into a common discharge pipe, the cross-sectional flow area of the
				  common discharge pipe shall be equal to or greater than the sum of the
				  individual temperature and pressure relief valve discharge pipe areas.
				  Discharge pipes shall be securely anchored and supported, as short and straight
				  as possible and arranged as to avoid undue stress on the valve or valves. A
				  union may be installed in the discharge piping close to the valve outlet. When
				  an elbow is placed on a pressure relief valve discharge pipe, it shall be
				  located close to the valve outlet downstream of the union to minimize reaction
				  moment stress;
(8) The discharge
				  from pressure relief valves shall be so arranged that there will be no danger
				  of scalding attendants. The pressure relief valve discharge shall be piped away
				  from the boiler to a safe point of discharge, and there shall be provisions
				  made for properly draining the piping. The size and arrangement of discharge
				  piping shall be such that any pressure that may exist or develop will not
				  reduce the relieving capacity of the relieving devices below that required to
				  protect the boiler; and
(9)
				  Hot-water heating or hot-water supply heating boilers limited to a water
				  temperature of 210 degrees Fahrenheit may have one or more NB capacity
				  certified temperature and pressure relief valve(s) installed. The requirements
				  of paragraphs (1) through (8) shall be met, except as follows:
(A) A Y-type fitting shall not be used;
				  and
(B) If additional valves are
				  used, they shall be temperature and pressure relief valves, and when the
				  temperature and pressure relief valve is installed directly on the boiler with
				  no more than four (4) inches maximum interconnecting piping, the valve may be
				  installed in the horizontal position with the outlet pointed down.