Current through September 24, 2024
(1) Automatic Low
Water Fuel Cutoff and/or Water Feeding Device.
(a) Each automatically-fired boiler shall be
equipped with one (1) or more automatic low water fuel cutoff devices
conforming to the requirements of ASME CSD-1, latest edition/addenda adopted by
the Board. If a waterfeeding device is installed, it shall be so constructed
that the water inlet valve cannot feedwater into the boiler through the float
chamber, and so located as to supply requisite feedwater. The lowest safe
waterline should not be lower than the lowest visible part of the water
glass.
(b) Such fuel or feedwater
control device may be attached directly to a boiler, or for low-pressure boiler
to the tapped openings provided for attaching a water glass directly to a
boiler, provided that such connections from the boiler are nonferrous tees or
Y's not less than one half (1/2) inch pipe size between the boiler and the
water glass, so that the water glass is attached directly and as close as
possible to the boiler. The ends of all nipples shall be reamed to full-size
diameter.
(c) Designs embodying a
float and float bowl shall have a vertical straightway valve drain pipe at the
lowest point in the water equalizing pipe connections by which the bowl and the
equalizing pipe can be flushed and the device tested.
(2) Boiler Blowoff Equipment.
(a) The blowdown from a boiler or boilers
that enters a sanitary sewer system or blowdown which is considered a hazard to
life or property shall pass through some form of blowoff equipment that will
reduce pressure and temperature as required hereunder.
1. The temperature of the water leaving the
blowoff equipment shall not exceed 150ºF.
2. The pressure of the blowdown leaving any
type of blowoff equipment shall not exceed 5 psig.
3. All blowoff equipment shall be fitted with
openings to facilitate cleaning and inspection.
(3) Boiler Door Latches.
(a) A watertube boiler shall have firing
doors of the inward-opening type, unless such doors are provided with
substantial and effective latching or fastening devices, or are otherwise so
constructed as to prevent them, when closed, from being blown open by pressure
on the furnace side. These latches or fastenings shall be of the positive
self-locking type. Friction contacts, latches, or bolts actuated by springs
shall not be used. The foregoing requirements for latches or fastenings shall
not apply to coal openings of downdraft or similar furnaces.
(b) All other doors, except explosion doors,
not used in the firing of the boiler, may be provided with bolts or fastenings
in lieu of self-locking latching devices.
(c) Explosion doors, if used and if located
in the setting walls within seven (7) feet of the firing floor or operating
platforms shall be provided with substantial deflectors to divert the
blast.
(4) Clearance.
(a) When boilers are replaced or new boilers
are installed in either existing or new buildings, a height of at least three
(3) feet shall be provided between the top of the boiler proper and the ceiling
or roof, and at least three (3) feet between all sides of the boiler and
adjacent walls or other structures. Boilers and pressure vessels having
manholes shall have five (5) feet clearance from the manhole opening and any
wall, ceiling or piping that will prevent a person from entering the boiler or
vessel. All boilers and pressure vessels shall be so located that adequate
space will be provided for the proper operation of the boilers and pressure
vessels and their appurtenances, for the inspection of all surfaces, tubes,
waterwalls, economizers, piping valves and other equipment, and for the
necessary maintenance, repair and replacement of tubes.
(b) A variance from the requirements of
subparagraph (a) of this rule may be issued by the Chief Inspector or Chief
Inspector's Designee for the installation of a steam heating, hot water
heating, hot water supply, or unfired steam boilers or unfired pressure
vessels. All requests must be submitted to the Chief Inspector or Chief
Inspector's Designee prior to installation.
(5) Exit from Boiler Room. Any boiler room
exceeding five hundred (500) square feet floor area and containing one (1) or
more boilers having a fuel-burning capacity of 1,000,000 BTU/hr, or equivalent
electrical heat input, shall have at least two (2) means of exit. Each exit
shall be remotely located from the other. Each elevation in such boiler room
shall have two (2) means of exit, each remotely located from the
other.
(6) Air and Ventilation
Requirements. Combustion Air Supply and Ventilation of Boiler Room. A permanent
source of outside air shall be provided for each boiler room to permit
satisfactory combustion of the fuel as well as proper ventilation of the boiler
room under normal operating conditions.
(a)
Total requirements of the burners for all fired pressure vessels in the boiler
room must be used to determine the louver sizes, whether fired by coal, oil or
gas; however, the minimum net free louvered area must not be less than one (1)
square foot. The following table or formula shall be used to determine the net
louvered area in square
|
Input BTU/Hour
|
Required Air Cu.Ft.
/Min.
|
Min. Net Louvered Area Sq.
Ft.
|
|
500,000
|
125
|
1.0
|
|
1,000,000
|
250
|
1.0
|
|
2,000,000
|
500
|
1.6
|
|
3,000,000
|
750
|
2.5
|
|
4,000,000
|
1,000
|
3.3
|
|
5,000,000
|
1,250
|
4.1
|
|
6,000,000
|
1,500
|
5.0
|
|
7,000,000
|
1,750
|
5.8
|
|
8,000,000
|
2,000
|
6.6
|
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(b) When
mechanical ventilation is used in lieu of subparagraph (a) of this rule, the
supply of combustion and ventilation air to the boiler room and the firing
devices shall be interlocked with the fan so the firing device will not operate
with the fan off. The velocity of the air through the ventilation fan shall not
exceed five hundred (500) feet per minute, and the total air delivered shall be
equal to or greater than shown in sub-paragraph (a) of this rule.
(7) Gas Burners. For installations
which are gas-fired, the burners used shall conform to the applicable
requirements of the American Gas Association, or other nationally recognized
standards acceptable to the Board.
(8) Prevention of Furnace Explosions.
Fuel-burning equipment, the related safety devices and controls, and their
operation shall be in accordance with the requirements of ASME CSD-1, or the
NFPA 85 latest edition/addenda adopted by the Board, as applicable.
(9) Electric Boilers. All appliances required
for electric steam boilers shall be attached in accordance with the following
rules:
(a) The grounding of the boiler shall
be permanently fastened on some part of the boiler, and shall be grounded in
accordance with the National Electrical Code, NFPA 70.
(b) A suitable screen or guard shall be
provided around high tension bushings; and a sign shall be posted warning of
high voltage. This screen or guard shall be so located that it will be
impossible for anyone working around the boiler to accidentally come in contact
with the high tension circuits. During the adjustment of safety valves, the
power circuit to the boiler shall be open. The boiler may be under steam or
water pressure, but the power line shall be open while the operator is making
the necessary adjustments.
(c) The
minimum safety valve or safety relief valve relieving capacity for electric
boilers shall be three and one half (31/2) pounds per hour per kilowatt
input.
(10) Flue
Connection. Each fuel-fired boiler shall be equipped with a vent or flue which
shall terminate at any acceptable location outside the building. The size of
the vent or flue and type of material shall be that recommended by the boiler
manufacturer.
(11) Attendants for
Power Boilers.
(a) A power boiler having a
rating of either 5 h.p. or 50 sq. ft. of heat-absorbing surface or greater
shall not be operated for periods of longer than twenty (20) minutes without
being checked pursuant to NB's recommendations, by an attendant who has been
qualified by the owner/user in its operation, regardless of whether the boiler
is equipped with automatic feedwater regulator, fuel or damper regulator, high
and low water alarm, or other form of automatic control.
(b) A variance from the requirements of
subparagraph (a) of this rule may be issued by the Board. All requests must be
submitted to the Chief Inspector or Chief Inspector's Designee no less than
forty-five (45) days prior to the next regularly scheduled or called meeting of
the Board.
(12)
Conditions not Covered. The Chief Inspector or Chief Inspector's Designee shall
be consulted for any conditions not covered by these requirements.
Authority:
T.C.A. §§
68-122-101,
68-122-102,
68-122-104,
and
68-122-106.
