HAR §12-222.1-6. to the safety valve outlet, or the discharge pipe shall be anchored and supported securely

If umbrella type drip pan connection is used, the discharge piping shall be designed to prevent binding due to expansion. (d) Capacity. The following shall apply to pressure relief valve capacity of power boilers: (1) The pressure relief valve capacity for each boiler shall be such that the valve or valves will discharge all the steam that can be generated by the boiler without allowing the pressure to rise more than six per cent (6%) above the maximum allowable working pressure of the boiler; (2) The minimum relieving capacity for other than electric boilers and forced-flow steam generators with no fixed steam line and waterline shall be estimated for the boiler and waterwall heating surfaces as given in NBIC Part I, Table 2.9.1.3 below, but in no case shall the minimum relieving capacity be less than the maximum designed steaming capacity as determined by the manufacturer; (3) The required relieving capacity, C, of the pressure relief valves on a high temperature water boiler shall be determined as follows: (A) C = Q/L; (B) C = required relieving capacity in lbs/hr (kg/hr); (C) Q = maximum output in BTUH (W) at the boiler nozzle obtained by the firing of any fuel for which the unit is designed; and (D) L = 1,000 BTU/lb (646W hr/kg); (4) The minimum pressure relief valve capacity for electric boilers shall not be less than 3.5 lbs/hr/KW input; and (5) If the pressure relief valve capacity cannot be computed, or if it is desirable to prove the computations, it should be checked by any one of the following methods; and if found insufficient, additional relieving 222.1-16 3559 §12-222.1-6 capacity shall be provided: (A) By performing an accumulation test by shutting off all other steam discharge outlets from the boiler and forcing the fires to maximum (this method should not be used on a boiler with a superheater or reheater, or on a high-temperature water boiler); (B) By measuring the maximum amount of fuel that can be burned and computing the corresponding evaporative capacity on the basis of the heating value of the fuel; or (C) By determining the maximum evaporative capacity by measuring the feedwater. The sum of the pressure relief valve capacities marked on the valves shall be equal to or greater than the maximum evaporative capacity of the boiler. This method should not be used on high-temperature water boilers. Table 2.9.1.3 MINIMUM POUNDS OF STEAM PER HOUR PER SQUARE FOOT OF HEATING SURFACE lb steam/hr ft² (kg steam/hr m³) | | Firetube Boiler | Watertube Boiler | | --- | --- | --- | | Boiler Heating Surface | | | | Hand-fired | 5 (24) | 6 (29) | | Stoker-fired | 7 (34) | 8 (39) | | Oil, gas, or pulverized coal | 8 (39) | 10 (49) | | | | | | Waterwall Heating Surface | | | | Hand-fired | 8 (39) | 8 (39) | | Stoker-fired | 10 (49) | 12 (59) | | Oil, gas, or pulverized coal | 14 (68) | 16 (78) | | | | | | Copper-finned Watertubes | | | | Hand-fired | | 4 (20) | | Stoker-fired | | 5 (24) | | Oil, gas, or pulverized coal | | 6 (29) | 222.1-17 3559 §12-222.1-6 # Notes: - When a boiler is fired only by a gas having a heat value not in excess of 200 Btu/ft.3(7.5MJ/m3), the minimum relieving capacity should be based on the values given for hand-fired boilers above. - The heating surface shall be computed for that side of the boiler surface exposed to the products of combustion, exclusive of the superheating surface. In computing the heating surface for this purpose only the tubes, fireboxes, shells, tubesheets, and the projected area of headers need to be considered, except that for vertical firetube steam boilers, only that portion of the tube surface up to the middle gage cock is to be computed. - For firetube boiler units exceeding 8,000 Btu/ft.2 (9,085 J/cm.2) (total fuel Btu (J) Input divided by total heating surface), the factor from the table will be increased by 1 (4.88) for every 1,000 Btu/ft.2 (1,136 J/cm.2) above 8,000 Btu/ft.2 (9,085 J/cm.2). For units less than 7,000 Btu/ft.2 (7,950 J/cm.2), the factor from the table will be decreased by 1 (4.88). - For watertube boiler units exceeding 16,000 Btu/ft.2 (18,170 J/cm.2) (total fuel Btu input divided by the total heating surface) the factor from the table will be increased by 1 (4.88) for every 1,000 Btu/ft.2 (1,136 J/cm.2) above 16,000 Btu/ft.2 (18,170 J/cm.2). For units with less than 15,000 Btu/ft.2 (17,034 J/cm.2), the factor in the table will be decreased by 1 (4.88) for every 1,000 Btu/ft.2 (1,136 J/cm.2) below 15,000 Btu/ft.2 (17,034 J/cm.2). (e) Location. The following shall apply to the location of the installation of pressure relief valves of power boilers: (1) Pressure relief valves shall be placed on, or as close as physically possible to, the boiler proper; (2) Pressure relief valves shall not be placed on the feedline; (3) Pressure relief valves shall be connected to the boiler independent of any other connection without any unnecessary intervening pipe or fittings. The intervening pipe or fittings shall not be longer than the face-to-face dimension of the corresponding tee fitting of the same diameter and pressure rating as listed in the applicable standards; (4) Every pressure relief valve shall be connected to stand in an upright position with spindle vertical; (5) The opening or connection between the boiler and the pressure relief valve shall have at least the area of the valve inlet, and the inlet pipe to the pressure relief valve shall be as short and straight as possible, no longer than twice the center-to-end (face) dimension of a corresponding tee fitting of the same diameter, pressure class, and connection type. When a discharge 222.1-18 2555