Section 12-222.1-12 - Operating requirements(a) Feedwater volume. The source of feedwater shall be capable of supplying a sufficient volume of water as determined by the boiler manufacturer to prevent damage to the boiler when all the safety relief valves are discharging at full capacity. (b) Feedwater connection. The following shall apply to feedwater connection: (1) To prevent thermal shock, feedwater shall be introduced into a boiler in such a manner that the water will not be discharged directly against surfaces exposed to high temperature gases or to direct radiation from the flame;(2) For boiler operating pressures of 400 psig or higher, the feedwater inlet through the drum shall be fitted with shields, sleeves, or other suitable means to reduce the effects of temperature differentials in the shell or head;(3) Feedwater other than condensate return shall not be introduced through the blowoff;(4) Boilers having more than 500 square feet of water heating surface shall have at least two means of supplying feedwater. For boilers that are fired with solid fuel not in suspension, and boilers whose setting or heat source can continue to supply sufficient heat to cause damage to the boiler if the feedwater supply is interrupted, one such means of supplying feedwater shall not be subject to the same interruption as the first method. Boilers fired by gaseous, liquid, or solid fuel in suspension may be equipped with a single means of supplying feedwater, provided means are furnished for the immediate removal of heat input if the supply of feedwater is interrupted;(5) For boilers having a water heating surface of not more than 100 square feet, the feedwater piping and connection to the boiler shall not be smaller than NPS 1/2. For boilers having a water heating surface more than 100 square feet, the feedwater piping and connection to the boiler shall not be less than NPS 3/4;(6) Electric boiler feedwater connections shall not be smaller than NPS 1/2; and(7) High-temperature water boilers shall be provided with means of adding water to the boiler or system while under pressure.(c) Pumps. The following shall apply to pumps: (1) Boiler feedwater pumps shall have discharge pressure more than the highest set pressure relief valve to compensate for frictional losses, entrance losses, regulating valve losses, and normal static head, etc. Each source of feedwater shall be capable of supplying feedwater to the boiler at a minimum pressure of three per cent (3%) higher than the highest setting of any pressure relief valve on the boiler proper. Detailed engineering evaluation of the pump selection shall be performed and available for review. Table 2.5.1.3 is a guideline for estimating feedwater pump differential; TABLE 2.5.1.3
GUIDE FOR FEEDWATER PUMP DIFFERENTIAL
Boiler Pressure | Boiler Feedwater Pump Discharge Pressure |
psig | (MPa) | psig | (MPa) |
200 | (1.38) | 250 | (1.72) |
400 | (2.76) | 475 | (3.28) |
800 | (5.52) | 925 | (6.38) |
1,200 | (8.27) | 1,350 | (9.31) |
(2) For forced-flow steam generators with no fixed steam or water line, each source of feedwater shall be capable of supplying feedwater to the boiler at a minimum pressure equal to the expected maximum sustained pressure at the boiler inlet corresponding to operation at maximum designed steaming capacity with maximum allowable pressure at the superheater outlet; and(3) Control devices may be installed on feedwater piping to protect the pump against overpressure.(d) Feedwater valves. The following shall apply to feedwater valves: (1) The feedwater piping shall be provided with a check valve and a stop valve. The stop valve shall be located between the check valve and the boiler;(2) When two or more boilers are fed from a common source, there shall also be a globe or regulating valve on the branch to each boiler located between the check valve and the feedwater source;(3) When the feedwater piping is divided into branch connections and all such connections are equipped with stop and check valves, the stop and check valve in the common source may be omitted;(4) On single boiler-turbine unit installations, the boiler feedwater stop valve may be located upstream from the boiler feedwater check valve;(5) If a boiler is equipped with duplicate feedwater supply arrangements, each such arrangement shall be equipped as required by these rules;(6) A check valve shall not be a substitute for a stop valve;(7) A combination feedwater stop-and-check valve in which there is only one seat and disk and a valve stem is provided to close the valve when the stem is screwed down shall be considered only as a stop valve; a separate check valve shall also be installed;(8) Whenever globe valves are used on feedwater piping, the inlet shall be under the disk of the valve;(9) Stop valves and check valves shall be placed on the inlet of economizers or feedwater-heating devices; and(10) The recirculating return line for a high-temperature water boiler shall be provided with the stop valve, or valves, required for the main discharge outlet on the boiler.(e) Blowoff. (1) Except for forced-flow steam generators with no fixed steam or water line, each boiler shall have a blowoff pipe, fitted with a stop valve, in direct connection with the lowest water space practicable. When the maximum allowable working pressure of the boiler exceeds one hundred (100) psig (700 kPa), there shall be two valves installed;(2) The blowoff piping for each electric boiler pressure vessel having a nominal water content not exceeding one hundred (100) gallons is required to extend through only one valve;(3) When two valves are required, each bottom blowoff pipe shall have two slow-opening valves, or one quick-opening valve, at the boiler nozzle followed by a slow-opening valve;(4) Two independent slow-opening valves, or a slow-opening valve and quick-opening valve, may be combined in one body provided the combined fitting is the equivalent of two independent slow-opening valves, or a slow-opening valve and a quick-opening valve, and the failure of one to operate cannot affect the operation of the other;(5) Straight-run globe valves or valves where dams or pockets can exist for the collection of sediment shall not be used;(6) The blowoff valve or valves and the pipe and fittings between them and the boiler shall be of the same size. The minimum size of pipe and fittings shall be NPS 1, except boilers with one hundred (100) square feet or less of heating surface should be NPS 3/4. The maximum size of pipe and fittings shall not exceed NPS 2-1/2;(7) For electric boilers, the minimum size of blowoff pipes and fittings shall be NPS 1, except for boilers of two hundred (200) kw input or less where the minimum size should be NPS 3/4;(8) Fittings and valves shall comply with the appropriate national standard except that austenitic stainless steel and malleable iron are not permitted;(9) When the maximum allowable working pressure exceeds one hundred 100 psig, blowoff piping shall be at least Schedule 80 and the required valves and fittings shall be rated for at least 1.25 times the maximum allowable working pressure of the boiler. When the maximum allowable working pressure exceeds 900 psig, blowoff piping shall be at least Schedule 80 and the required valves and fittings shall be rated for at least the maximum allowable working pressure of the boiler plus 225 psi;(10) All blowoff piping, when exposed to furnace heat, shall be protected by fire brick or other heat resisting material so constructed that the piping may be readily inspected;(11) On a boiler having multiple blowoff pipes, a single master stop valve should be placed on the common blowoff pipe from the boiler and one stop valve on each individual blowoff. Either the master valve or the valves on the individual blowoff lines shall be of the slow-opening type;(12) The discharge of blowoff pipes shall be located so as to prevent injury to personnel;(13) All waterwalls or water screens that do not drain back into the boiler and integral economizers forming part of a boiler shall be equipped with blowoff piping and valves conforming to the requirements of this subsection;(14) Blowoff piping from a boiler should not discharge directly into a sewer. A blowoff tank, constructed to the provisions of a code of construction acceptable to the jurisdiction, shall be used where conditions do not provide an adequate and safe open discharge;(15) Galvanized pipe shall not be used;(16) Boiler blowoff systems should be constructed in accordance with the Guide for Blowoff Vessels (NB-27), which can be found on the National Board website at www.nationalboard.org;(17) Where necessary to install a blowoff tank underground, it shall be enclosed in a concrete or brick pit with a removable cover so that inspection of the entire shell and heads of the tank can be made; and(18) Piping connections used primarily for continuous operation, such as deconcentrators on continuous blowdown systems, are not classed as blowoffs; but the pipe connections and all fittings up to and including the first shutoff valve shall be equal at least to the pressure requirements for the lowest set pressure of any safety valve on the boiler drum and with the corresponding saturated-steam temperature. Further, such connections shall not exceed NPS 2-1/2.(f) Drains. Each boiler shall have at least one drainpipe fitted with a stop valve at the lowest point of the boiler. If the connection is not intended for blowoff purposes, a single valve is acceptable if it can be locked in the closed position or a blank flange can be installed downstream of the valve. If the connection is intended for blowoff purposes, requirements of (e) shall be followed. (1) For high temperature water boilers, the minimum size of the drainpipe shall be NPS 1; and(2) Drainpipes, valves, and fittings within the same drain line shall be the same size.(g) Electrical. A disconnecting means capable of being locked in the open position shall be installed at an accessible location at the boiler so that the boiler can be disconnected from all sources of potential. This disconnecting means shall be an integral part of the boiler or adjacent to it.(h) Wiring. All wiring for controls, heat generating apparatus, and other appurtenances necessary for the operation of the boiler or boilers should be installed in accordance with the provisions of national or international standards and comply with the applicable local electrical codes.(i) Remote emergency shutdown switches. The following shall apply to remote emergency shutdown switches: (1) A manually operated remote shutdown switch or circuit breaker shall be located just outside the equipment room door and marked for easy identification. Consideration should also be given to the type and location of the switch to safeguard against tampering. Where approved by the department, alternate locations of remote emergency switches may be provided;(2) For equipment rooms exceeding 500 square feet floor area, or containing one or more boilers having a combined fuel capacity of 1,000,000 Btu/hr or more, additional manually operated remote emergency shutdown switches shall be located at suitably identified points of egress acceptable to the department;(3) Where a boiler is located indoors in a facility and not in an equipment room, a remote emergency shutdown switch shall be located within fifty (50) feet of the boiler along the primary egress route from the boiler area;(4) For atmospheric-gas burners and for oil burners where a fan is on the common shaft with the oil pump, the emergency remote shutdown switches or circuit breakers must disconnect all power to the burner controls;(5) For power burners with detached auxiliaries, the emergency remote shutdown switches or circuit breakers need only shut off the fuel input to the burner; and(6) When existing boiler installations do not include remote emergency shutdown switches, it is not required that these switches be retroactively installed unless required by the department.Haw. Code R. § 12-222.1-12
[Eff and comp 12/21/2019] (Auth: HRS § 397-4) (Imp: HRS § 397-4)