Mississippi Administrative Code › Title 15 - Mississippi Department of Health › Part 10 - Boiler and Pressure Vessel Safety › Subpart 76 - Boiler and Pressure Vessel Safety Act and Rules and Regulations › Chapter 3 - Existing Installations › Subchapter 2 - Heating Boilers › Rule 15-10-76-3.2.6 - Safety Relief Valve Requirements for Hot Water Boilers

Current through June 25, 2024
1. Each hot water heating boiler shall have
					 at least one officially rated (ASME approved and National Board rated) safety
					 relief valve set to relieve at or below the maximum allowable working pressure
					 of the boiler. Each hot water supply boiler shall have at least one officially
					 rated safety relief valve of the automatic reseating type set to relieve at or
					 below maximum allowable working pressure of the boiler. Safety relief valves
					 officially rated as to capacity shall have pop action when tested by steam.
					 When more than one safety relief valve is used on either hot water heating or
					 hot water supply boilers, the additional valve or valves shall be officially
					 rated and may be set within a range not to exceed 6 psi above the maximum
					 allowable working pressure of the boiler up to and including 60 psig and 10
					 percent for those having maximum allowable working pressure exceeding 60 psig.
					 Safety relief valves shall be spring loaded. Safety relief valves shall be so
					 arranged that they cannot be reset at a higher pressure than the maximum
					 permitted by this paragraph.
2. No
					 materials liable to fail due to deterioration or vulcanization when subject to
					 saturated steam temperature corresponding to capacity test pressure shall be
					 used for any part.
3. No safety
					 relief valve shall be smaller than 3/4 inch nor larger than 4 1/2 inches
					 standard pipe size, except that boilers having a heat input not greater than
					 15,000 BTU per hour may be equipped with a rated safety relief valve of 1/2
					 inch standard pipe size. The inlet opening shall have an inside diameter
					 approximately equal to or greater than, the seat diameter. In no case shall the
					 minimum opening through any part of the valve be less than 1/4 inch diameter or
					 its equivalent area.
4. The
					 required steam relieving capacity, in pounds per hour, of the pressure
					 relieving device or devices on a boiler shall be the greater of that determined
					 by dividing the maximum output in BTU at the boiler outlet obtained by the
					 firing of any fuel for which the unit is installed by 1,000, or on the basis of
					 pounds of steam generated per hour per square foot of boiler heating surface as
					 given in Table 2. In many cases, a greater relieving capacity of valves will
					 have to be provided than the minimum specified by these rules. In every case,
					 the requirements of (f) shall be met.
5. When operating conditions are changed, or
					 additional boiler heating surface is installed, the valve capacity shall be
					 increased, if necessary, to meet the new conditions and shall be in accordance
					 with (f). The additional valves required, on account of changed conditions, may
					 be installed on the outlet piping provided there is no intervening
					 valve.
6. Safety relief valve
					 capacity for each boiler shall be such that, with the fuel burning equipment
					 installed and operated at maximum capacity, the pressure cannot rise more than
					 6 psi above the maximum allowable working pressure for pressure up to and
					 including 60 psig and 10 percent of maximum allowable working pressures over 60
					 psig.
7. If there is any doubt as
					 to the capacity of the safety relief valve, an accumulation test shall be run
					 (see ASME Code, Section VI, Care of Heating Boilers).
8. No valve of any description shall be
					 placed between the safety relief valve and the boiler, nor on the discharge
					 pipe between the safety relief valve and the atmosphere. The discharge pipe
					 shall be at least full size and fitted with an open drain to prevent water
					 lodging in the upper part of the safety relief valve or in the discharge pipe.
					 When an elbow is placed on the safety relief valve discharge pipe, it shall be
					 located close to the safety relief valve outlet or the discharge pipe shall be
					 securely anchored and supported. All safety relief valve discharges shall be so
					 located or piped as not to endanger persons working in the area.
Miss. Code Ann.
						§
												45-23-9