| (B) In boilers with a fixed water line, the low-water
fuel cutoff devices shall be tested regularly by lowering the water
level sufficiently to shut off the fuel supply to the burner when
the water level reaches the lowest safe level for operation. Boilers
that do not have a fixed water line shall be equipped with a flow
sensing device, thermal couple or expansion ring that is listed by
a nationally recognized testing agency to prevent burner operation
at a flow rate inadequate to protect the boiler unit against overheating.
(C) The low-water cutoff shall be rated for a pressure
and temperature equal to or greater than the MAWP and temperature
of the boiler.
(D) For High-Temperature Water Boilers requiring forced
flow circulation, an approved flow sensing device shall be installed
on the outlet, as close to the boiler as possible.
(2) When a low-water fuel cutoff and feedwater pump
control is combined in a single device, an additional separate low-water
fuel cutoff shall be installed. The additional control shall be wired
in series electrically with the existing low-water fuel cutoff.
(3) When a low-water fuel cutoff is housed in either
the water column or a separate chamber it shall be provided with a
blowdown pipe and valve not less than 3/4 inch nominal pipe size (20
mm). The arrangement shall be such that when the water column is blown
down, the water level in it will be lowered sufficiently to activate
the lower-water fuel cutoff device.
(4) If a water feed device is utilized, it shall be
constructed to prevent feedwater from entering the boiler through
the water column or separate chamber of the low-water fuel cutoff.
(e) Pressure gages.
(1) Each boiler shall have a pressure gage that is
readable.
(A) The dial of the pressure gage shall be graduated
to approximately double the pressure at which the safety valve is
set, but in no case, less than one and one-half times this pressure.
(B) The pressure gage shall be connected to the steam
space, to the water column, or its steam connection.
(C) A valve or cock shall be placed in the gage connection
adjacent to the gage.
(D) An additional valve or cock may be located near
the boiler providing it is locked or sealed in the open position.
(E) No other shutoff valves shall be located between
the gage and the boiler.
(F) The pipe connection shall be of ample size and
arranged so that it may be cleared by blowing down.
(G) For a steam boiler, the gage or connection shall
contain a siphon or equivalent device which will develop and maintain
a water seal that will prevent steam from entering the gage tube.
(2) Each boiler shall have a valved connection at least
1/4 inch nominal pipe size (6 mm) connected to the steam space for
the exclusive purpose of attaching a test gage when the boiler is
in service to test the accuracy of the pressure gage.
(f) Stop valves.
(1) Each steam outlet from a boiler (except safety
valve connections) shall be fitted with a stop valve located as close
as practicable to the boiler.
(2) When a stop valve is located that allows water
to accumulate, ample drains shall be provided. The drain shall be
piped to a safe location and shall not be discharged on the boiler
or its setting.
(3) When boilers provided with manholes or other similar
opening that permits access for human occupancy and that are connected
to a common steam main, the steam connection from each boiler shall
be fitted with two stop valves, with an ample drain between them.
The discharge of the drain shall be visible to the operator while
manipulating the valves and shall be piped clear of the boiler setting.
Best practice is for the first valve to be an automatic nonreturn
valve (set next to the boiler), and a second valve of the outside-screw-and-yoke
type.
(g) Blowdown connection.
(1) The construction of the setting around each blowdown
pipe shall permit free expansion and contraction. These setting openings
must be sealed without restricting the movement of the blowdown piping.
(2) All blowdown piping, when exposed to furnace heat,
shall be protected by firebrick or other heat-resisting material,
and constructed to allow the piping to be inspected.
(3) Each boiler shall have a blowdown pipe, fitted
with a valve or cock, in direct connection with the lowest water space.
The piping shall be run full size without the use of a reducer or
bushings and shall not be galvanized. Cocks shall be of gland or guard
type and suitable for the pressure allowed. The use of globe valves
shall be in accordance with ASME code.
(4) When the MAWP exceeds 100 psig (700 kilopascals),
the piping shall be at least schedule 80 steel and shall not be galvanized.
Each blowdown pipe shall be provided with two valves or a valve and
cock, such valves and cocks shall be adequate for design conditions
of the boiler.
(5) All fittings between the boiler and blowdown valve
shall be of steel or extra-heavy malleable iron. In case of renewal
of blowdown pipe or fittings, they shall be installed in accordance
with the requirements of the applicable section of the ASME code.
(6) It is recommended that blowdown tanks be designed,
constructed, and installed in accordance with National Board recommended
rules for boiler blowoff equipment.
(h) Boiler external piping. All boiler external piping,
as referenced in the ASME code, shall be examined for compliance to
the boiler's code of construction and shall be documented in the appropriate
block on the inspection report.
(i) Provisions for thermal expansion for High-Temperature
Water Boilers.
(1) An airtight tank or other suitable air cushion
that is consistent with the volume and capacity of the system shall
be installed. Expansion tanks shall be constructed in accordance with
the ASME Code, Section VIII, Division 1, and the pressure and temperature
ratings of the tank shall be equal to or greater than the pressure
and temperature ratings of the system pressure. A pressure relief
valve shall be installed with a set pressure at or below the MAWP
of the expansion tank. Alternately the boiler pressure relief valve
may be used provided the expansion tank's MAWP is equal to or greater
than the set pressure of the pressure relief valve.
(2) Provisions shall be made for draining the tank
without emptying the system, except for pre-pressurized tanks.
(3) If the expansion tank was originally equipped with
a sight glass, the sight glass and sight glass valves shall be in
working condition at all times, and the water level shall be maintained
as per the manufacturer's recommendations.
|
| Source Note: The provisions of this §65.607 adopted to be effective June 15, 2015, 40 TexReg 3121; amended to be effective January 15, 2018, 43 TexReg 75; amended to be effective September 1, 2018, 43 TexReg 5361; amended to be effective July 1, 2020, 45 TexReg 4330 |
