USACE / NAVFAC / AFCESA / NASA UFGS-23 52 46.00 20 (April 2006)
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Preparing Activity: NAVFAC Replacing without change
UFGS-15515N (June 2005)
UNIFIED FACILITIES GUIDE SPECIFICATIONS
References are in agreement with UMRL dated January 2009
SECTION 23 52 46.00 20
LOW PRESSURE WATER HEATING BOILERS (OVER 800,000 BTU/HR OUTPUT)
04/06
NOTE: This guide specification covers the requirements for low pressure hot
water heating boilers over 235 kilowatt 800,000 BTU/hr output.
Edit this guide specification for project specific requirements by adding, deleting,
or revising text. For bracketed items, choose applicable items(s) or insert
appropriate information.
Remove information and requirements not required in respective project, whether
or not brackets are present.
Comments and suggestions on this guide specification are welcome and should
be directed to the technical proponent of the specification. A listing of technical
proponents, including their organization designation and telephone number, is
on the Internet.
Recommended changes to a UFGS should be submitted as a Criteria Change Request
(CCR).
PART 1 GENERAL
1.1 REFERENCES
NOTE: This paragraph is used to list the publications cited in the text of
the guide specification. The publications are referred to in the text by basic
designation only and listed in this paragraph by organization, designation,
date, and title.
Use the Reference Wizard's Check Reference feature when you add a RID outside
of the Section's Reference Article to automatically place the reference in the
Reference Article. Also use the Reference Wizard's Check Reference feature
to update the issue dates.
References not used in the text will automatically be deleted from this section
of the project specification when you choose to reconcile references in the
publish print process.
The publications listed below form a part of this specification to the extent referenced. The publications are
referred to within the text by the basic designation only.
[AMERICAN NATIONAL STANDARDS INSTITUTE (ANSI)ANSI Z83.3(1971; R 1995) Gas Utilization Equipment in Large Boilers][ASME INTERNATIONAL (ASME)ASME BPVC SEC IV(2007; Addenda 2008) Boiler and Pressure Vessel Code; Section IV, Recommended Rules for the Care and Operation of Heating BoilersASME CSD-1(2006) Control and Safety Devices for Automatically Fired Boilers][ASTM INTERNATIONAL (ASTM)ASTM A 53/A 53M(2007) Standard Specification for Pipe, Steel, Black and Hot-Dipped, Zinc-Coated, Welded and SeamlessASTM C 592(2008a) Standard Specification for Mineral Fiber Blanket Insulation and Blanket-Type Pipe Insulation (Metal-Mesh Covered) (Industrial Type)][NATIONAL FIRE PROTECTION ASSOCIATION (NFPA)NFPA 211(2006) Chimneys, Fireplaces, Vents, and Solid Fuel-Burning AppliancesNFPA 85C(1991) Prevention of Furnace Explosions in Fuel Oil- and Natural Gas-Fired Single Burner Boiler-Furnaces][U.S. GENERAL SERVICES ADMINISTRATION (GSA)FS F-B-2903(Basic) Boilers, Steam and ot Water, Firetube, Scotch Packaged Type (320,001 to 35,000,000 BTU/HR Thermal Output Capacity)FS F-B-2910(Basic) Burners, Single Oil, Gas, and Gas-Oil Combination for Packaged Boilers (320,001 to 125,000,000 BTU/HR Thermal Output Capacity)FS F-F-2901Feeders, Boiler Water Treatment, By-Pass and Compound Receiver Types][UNDERWRITERS LABORATORIES (UL)UL 726(1995; Rev thru Mar 2006) Oil-Fired Boiler AssembliesUL 795(2006) Commercial-Industrial Gas Heating Equipment]1.2 RELATED REQUIREMENTS
Section 23 03 00.00 20 BASIC MECHANICAL MATERIALS AND METHODS, applies to this section, with the additions and
modifications specified herein.
1.3 DESIGN REQUIREMENTS
NOTE: Insert boiler output capacity or indicate in boiler schedule. Select
boiler design working pressure, operating pressure, operating temperature, and
return water temperature and indicate in boiler schedule.
Boiler shall be suitable for installation in the space shown with ample room for opening doors and cleaning and
removal and replacement of tubes. Boiler shall have an output of [_____] kW BTU per hour with an efficiency of
not less than required by the applicable military specification. Boiler shall be designed, tested, and installed
in accordance with ASME BPVC SEC IV and ASME CSD-1. Boiler shall be complete with an explosion-relief door,
located in accordance with manufacturer's recommendations. Paint boiler in accordance with manufacturer's standard
requirements. Boiler design working pressure shall be [207 kPa (gage)] [30 psig] [_____]. Boiler operating
pressure shall be [83 kPa (gage)] [12 psig] [_____]. Boiler operating temperature shall be [82 degrees C] [180
degrees F] [_____]. Boiler return water temperature shall be [71 degrees C] [160 degrees F] [_____]. Provide
a thermostatically controlled three-way mixing valve on the water supply to the boiler suitable for operating
conditions of the boiler.
1.3.1 Detail Drawings
Submit fuel trains schematic and wiring diagrams.
1.3.2 Water Analysis
Provide test reports of water analysis.
1.3.3 Safety Standards
Hot water boilers, burners, and any supplementary control devices, safety interlocks, or limit controls required
under this specification shall meet requirements of the following standards as applicable:
a. Oil-Fired Units: UL 726 or NFPA 85C.
b. Gas-Fired Units: UL 795, NFPA 85C, or ANSI Z83.3.
c. Combination Gas and Oil-Fired Units: UL 726, UL 795, NFPA 85C, or ANSI Z83.3.
d. All Units: ASME BPVC SEC IV and ASME CSD-1.
Controls not covered by the above shall have a UL label, UL listing mark, or shall be listed in the Factory Mutual
Approval Guide.
1.4 SUBMITTALS
NOTE: Review submittal description (SD) definitions in Section 01 33 00 SUBMITTAL
PROCEDURES and edit the following list to reflect only the submittals required
for the project. Submittals should be kept to the minimum required for adequate
quality control.
A “G” following a submittal item indicates that the submittal requires Government
approval. Some submittals are already marked with a “G”. Only delete an existing
“G” if the submittal item is not complex and can be reviewed through the Contractor’s
Quality Control system. Only add a “G” if the submittal is sufficiently important
or complex in context of the project.
For submittals requiring Government approval on Army projects, a code of up
to three characters within the submittal tags may be used following the "G"
designation to indicate the approving authority. Codes for Army projects using
the Resident Management System (RMS) are: "AE" for Architect-Engineer; "DO"
for District Office (Engineering Division or other organization in the District
Office); "AO" for Area Office; "RO" for Resident Office; and "PO" for Project
Office. Codes following the "G" typically are not used for Navy, Air Force,
and NASA projects.
Choose the first bracketed item for Navy, Air Force and NASA projects, or choose
the second bracketed item for Army projects.
Government approval is required for submittals with a "G" designation; submittals not having a "G" designation
are [for Contractor Quality Control approval.][for information only. When used, a designation following the
"G" designation identifies the office that will review the submittal for the Government.] The following shall
be submitted in accordance with Section 01 33 00 SUBMITTAL PROCEDURES:
NOTE: Include the following paragraph for SOUTHNAVFACENGCOM projects.
[Submittals for this Section shall be delivered to the Contracting Officer, who shall forward two complete sets
of copies to the Commanding Officer, Southern Division, Naval Facilities Engineering Command, Code 16B, for review
and approval.]
SD-02 Shop Drawings
Fuel trains
Wiring diagrams
SD-03 Product Data
Boilers: power output, efficiency, ASME certification, allowable working pressure, model number
Boiler trim and control equipment
Burners and control equipment
Stack, breeching, and supports
SD-06 Test Reports
Operational tests
SD-07 Certificates
Boilers
Burners and control equipment
Boiler trim and control equipment
Water analysis
Boilers
Boiler trim and control equipment
Burners and control equipment
Boiler manufacturer's certificate of boiler performance including evidence that the burners
provided shall be a make, model, and type certified and approved by the manufacturer of the
boiler being provided.
SD-08 Manufacturer's Instructions
Boilers
Feedwater treatment system
SD-10 Operation and Maintenance Data
Boilers, Data Package 4
Submit in accordance with Section 01 78 23 OPERATION AND MAINTENANCE DATA.
SD-11 Closeout Submittals
Posted operating instructions for heating water boilers
PART 2 PRODUCTS
2.1 BOILERS
NOTE: Select boiler size required.
Shall conform to the applicable requirements of FS F-B-2903. Hot-water boilers shall be horizontal firetube,
multipass, modified scotch-type of the dry or wet-back type, packaged units mounted on a skid-type structural
steel base. Provide each boiler complete burner and fuel system, a forced or induced draft fan, an automatic
electronic control system complete with combustion and flame safeguard controls, firing sequence programmer,
safety interlocks, limit controls and central control panel, and such trim and appurtenances as are peculiar
to water units as specified herein. Units shall be factory-wired and assembled except for such readily installed
appurtenances as safety valves, water columns, and pressure gages. Units shall be complete and ready for operation
when connected to water, fuel, and electrical supplies.
2.2 BURNERS AND CONTROL EQUIPMENT
NOTE: Indicate fuel trains on the drawings. Conform to the requirements of
ASME CSD-1 and FS F-B-2910. See FS F-B-2910 for guidelines for selection of
a combustion control system.
[2.2.1 Gas-Fired Power Burner
FS F-B-2910, Class 3 - gas-fired, automatic recycling. Interrupted pilot type ignition system, and pilot shall
be electrode-ignited natural gas type. The combustion control system shall be the [high-low-off] [positioning]
[metering] type. Design burner and combustion-control equipment for firing natural gas having a specific gravity
of [0.6] [_____] and a heating value of approximately [_____] [37,300] kJ per cubic meter [_____] [1000] BTU
per cubic foot and be an integral part of the boiler. Burner controls and safety equipment shall conform to
the applicable requirements of FS F-B-2910. Mount controls; including operating switches, indicating lights,
gages, alarms, motor starters, fuses, and circuit elements of control systems on a single control panel or cabinet
designed for separate mounting not on the burner in accordance with FS F-B-2910. Locate flame scanner such that
testing and cleaning of scanner can be accomplished without disassembly of burner. Provide fuel train as indicated.
Gas pressure available: [_____ Pa in. wc] [_____ kPa (gage) psig].
][2.2.2 Oil-Fired Power Burner
FS F-B-2910, Class 2 - Light Oil-Fired, automatic recycling. [Pressure-atomizing] [Air-atomizing; compressor
or pump furnished with the burner] type burner. The combustion control system shall be the [high-low-off][positioning]
[metering] type. Ignition system shall be [direct electric-spark-ignited type] [interrupted pilot type, and
pilot shall be [electrode-ignited [natural] [propane] gas type] [light oil spark-ignition type]]. Design burner
and combustion control equipment for firing commercial grade no. 2 fuel oil and be an integral part of boiler.
Burner controls and safety equipment shall conform to applicable requirements of FS F-B-2910. Mount controls;
including operating switches, indicating lights, gages, alarms, motor starters, fuses, and circuit elements of
control systems on a single control panel or cabinet designed for separate mounting not on burner in accordance
with FS F-B-2910. Locate flame scanner such that testing and cleaning of scanner can be accomplished without
disassembly of burner. [Provide fuel train as indicated.] Oil fired boilers shall have a steady state combustion
efficiency of at least 83 percent.
][2.2.3 Combination Gas and Light Oil-Fired Power Burner
FS F-B-2910, Class 5 - combination light oil and gas-fired. Automatic recycling burner. The combustion control
system shall be the[high-low-off][positioning] [metering] type. Partial pre-mix type gas burner, complete with
primary air fan. [Pressure-atomizing] [Air-atomizing; compressor or pump furnished with burner] type oil burner.
Ignition system for firing natural gas shall be interrupted pilot type, and pilot be electrode-ignited natural
gas type. Ignition system for firing light oil shall be the [direct electric-spark-ignited type] [interrupted
pilot type, and pilot shall be [electrode-ignited [propane] [natural] gas type] [light oil spark-ignition type]].
Design burner and combustion control equipment for firing commercial grade number 2 fuel oil and natural gas
having a specific gravity of [0.6] [_____] and a heating value of approximately [_____] [37,300] kJ per cubic
meter [_____] [1000] BTU per cubic foot and be an integral part of boiler. Burner controls and safety equipment
shall conform to applicable requirements of FS F-B-2910. Mount controls; including operating switches, indicating
light, gages, alarms, motor starters, fuses, and circuit elements of control systems on a single control panel
or cabinet designed for separate mounting not on the burner in accordance with FS F-B-2910. Locate flame scanner
such that testing and cleaning of scanner can be accomplished without disassembly of burner. Provide fuel train
as indicated. Gas pressure available: [_____ Pa in. wc] [_____ kPa (gage) psig].
]2.3 BOILER TRIM AND CONTROL EQUIPMENT
Provide in accordance with FS F-B-2903 and FS F-B-2910. Boiler trim shall comply with ASME BPVC SEC IV and additional
appurtenances specified below. Non-recycling control interlocks shall have the reset located on control interlock.
2.3.1 Emergency Disconnect Switch
NOTE: Indicate location of emergency disconnect switch on drawings. Insert
emergency switch amperage required.
Provide and locate on wall outside boiler room entrance or just inside door, when boiler room door is on the
building exterior to allow rapid and complete shutdown of the boiler in the event of an emergency. Emergency
switch shall be a [_____]-amp. fuse-type safety switch. Switch shall be red and furnished with a label indicating
function of switch.
2.3.2 Relief Valves
Provide relieving capacity for the full output of boiler installed. Relief-valve piping shall conform to ASTM A 53/A 53M
, schedule 40 steel pipe and be piped full size [to a floor drain] [to 150 mm 6 inches above floor].
2.3.3 Pressure Gage
FS F-B-2903. Provide with a scale equivalent to 1.5 time outlet water pressure with a 150 mm 6 inch diameter.
Locate one on supply water piping and one on the return water piping.
2.3.4 Thermometers
Provide thermometers with a scale equivalent to 1.5 times the outlet water temperature. Provide one located
on supply water piping and one on return water piping.
2.3.5 Drain Tapping
Provide drain valve and piping [to a floor drain] [to 150 mm 6 inches above floor].
2.3.6 Make-up Water Station
2.3.6.1 Pressure Reducing Station
NOTE: Select operating pressure required.
Provide a water pressure-reducing valve and relief valve, or a combination of the two in the makeup water line
to the boiler to maintain a water pressure of [_____] [83] kPa (gage) [_____] [12] psig in the hot water system.
Provide a 20 mm 3/4 inch globe valve by-pass around this valve.
2.3.6.2 Backflow Preventers
Section 22 00 00 PLUMBING SYSTEMS. Locate upstream of by-pass.
2.3.7 Stack Thermometer
Provide flue gas-dial type thermometer with scale calibrated from 66 to 399 degrees C 150 to 750 degrees F and
mount in flue gas outlet.
2.3.8 Air Vent Valve
Provide with screwed connections, stainless steel disk, and stainless steel seats to vent entrapped air from
boiler.
2.3.9 Feedwater Treatment System
Provide in accordance with FS F-F-2901, Type II - shot-type feeder (manual, intermittent feed), Style A - for
use with pressure up to 1379 kPa (gage) 200 psig maximum.
2.3.10 Combustion Regulator
Provide adjustable temperature, thermostatic immersion type that shall limit boiler water temperature to a maximum
of 121 degrees C 250 degrees F. Control shall actuate burner through an electric relay system to maintain boiler
water temperature within normal prescribed limits at loads within rated capacity of boiler.
2.3.11 High Temperature Limit Switch
Provide immersible aquastat type with a temperature setting above that of the combustion regulator and below
that of the lowest relief valve setting. Aquastat shall function to cause a safety shutdown by closing fuel
valves, shutting down burner equipment, activating a red indicating light, and sounding an alarm in the event
that boiler water temperature rises to the high temperature limit setting. A safety shutdown due to high temperature
shall require manual reset before operation can resume and shall prevent recycling of the burner equipment.
2.3.12 Low Water Pressure Control
Provide mercury switch type. Control shall have a main scale, adjusting screws at the top of the case, and have
an internal or external bellows. Control shall be of the type which will open an electric circuit on a drop
in pressure below a set minimum. Control shall be set and installed to cause a safety shutdown by closing fuel
valves, shutting down burner equipment, activating a red indicating light, and sounding an alarm in the event
that water pressure in the system drops below [83 kPa (gage)] [12 psig] [_____]. A safety shutdown due to low
water pressure shall require manual reset before operation can resume and prevent recycling of burner equipment.
2.3.13 Low Water Level Cutoff Switch
Provide float actuated type. Low water level cutoff shall cause a safety shutdown by closing fuel valves, shutting
down burner equipment, activating a red indicating light, and sounding an alarm in the event that water level
drops below the lowest safe permissible water level established by the boiler manufacturer and ASME BPVC SEC IV
. A safety shutdown due to low water level shall require manual reset before operation can resume and prevent
recycling of burner equipment.
2.3.14 Low Water Flow Interlock
Low water flow interlock required by FS F-B-2903 is not required.
2.3.15 Boiler Safety Control Circuits
Provide boiler safety control circuits, including control circuits for burner and draft fan, shall be single-phase,
two-wire one-side grounded, and not over 120 volts. Provide safety control switching in ungrounded conductors.
Provide overcurrent protection. In addition to circuit grounds, ground metal parts which do not carry current
to a grounding conductor.
2.3.16 Indicating Lights
NOTE: Include indicating lights for low gas pressure and high gas pressure
on all but size 1 burners.
Provide indicating lights as follows. Each safety interlock requiring a manual reset shall have an individually-labeled
indicating light. Non-recycling controls/interlocks shall have the reset located on control/interlock itself.
Indicating lights shall have colors as follows
in lieu of the colors required by FS F-B-2910:
a. Amber: Ignition on
b. Blue: Draft
c. Green: Main fuel safety shut-off valves open
d. Red (One for Each): Safety lockout flame failure and low water pressure, low water level,
[and] high temperature [, low gas pressure, and high gas pressure].
2.3.17 Alarm Bell
Provide alarm bell not less than 100 mm 4 inches in diameter, electrically operated, with a manual disconnect.
Disconnect switch shall be type and wired so that switching off alarm following a safety shutdown will not prevent
alarm from sounding again upon recurrence of a subsequent safety shutdown condition.
2.3.18 Post-Combustion Purge
NOTE: Select four-air-change purge for Size 1, Size 2, and Size 3 burners.
Select eight-air-change purge for Size 4 burners.
Provide a post-combustion purge in addition to the operating sequence required by FS F-B-2910. Provide controls
and wiring necessary to assure operation of draft fan for a period of not less than 15 seconds or of sufficient
duration to provide [four] [eight] complete air changes in the boiler combustion chamber (whichever is greater)
following shutdown of burner upon satisfaction of heat demand. Upon completion of post-combustion purge period,
draft fan shall automatically shutdown until next restart.
2.3.19 Draft
Comply with boiler manufacturer's recommendations.
2.3.20 Stack, Breeching, and Supports
Provide boiler stack constructed of sheet steel having a thickness of not less than 2.47 mm 0.0972 inches with
welded joints. Insulate stack located inside the building with 38 mm 1 1/2 inches of mineral wool conforming
to applicable requirements of ASTM C 592, Class II - for use up to 649 degrees C 1200 degrees F. Insulation
shall receive a finish coat of finishing cement not less than 19 mm 3/4 inch thick, trowelled to a smooth finish.
Provide stack supports, umbrella collar and cap, and flue transition piece. Stack diameter and height shall
be in accordance with manufacturer's recommendation and conform to NFPA 211.
2.3.21 Hot-Water Coils
NOTE: Delete entire paragraph unless hot-water coils are required to instantaneously
heat domestic water.
Provide coils capable of heating [_____] L/s GPM of water with [_____] degrees C F rise conforming to FS F-B-2903
.
2.3.22 Smoke Density Indicator
NOTE: Specify only if input exceeds 1465 kW 5,000,000 BTU/hr.
2.3.23 Annunciator
NOTE: Specify only if input exceeds 1465 kW 5,000,000 BTU/hr.
Provide in accordance with FS F-B-2910.
2.4 ELECTRIC MOTORS
NOTE: Select standard efficiency for motors used less than 750 hours per year
and high efficiency for motors used over 750 hours per year. Packaged boilers
should utilize the manufacturer's standard efficiency motor.
Motors which are not an integral part of a packaged boiler shall be rated for [standard] [high] efficiency service
per Section 26 20 00 INTERIOR DISTRIBUTION SYSTEM. Motors which are an integral part of the packaged boiler
system shall be the highest efficiency available by the manufacturer of the packaged boiler.
PART 3 EXECUTION
3.1 EQUIPMENT INSTALLATION
Install equipment in accordance with the manufacturer's installation instructions. Grout equipment mounted on
concrete foundations before installing piping. Install piping in such a manner as not to place a strain on equipment.
Do not bolt flanged joints tight unless they match. Grade, anchor, guide, and support piping without low pockets.
Feedwater treatment feeders shall be mounted so that the top of the feeder is not higher than 1219 mm 48 inches
above the finished floor.
3.2 EQUIPMENT FOUNDATIONS
Locate equipment foundations as indicated, designed, and made of sufficient size and weight to preclude shifting
of equipment under operating conditions or under any abnormal conditions that could be imposed upon the equipment.
Foundations shall meet requirements of the equipment manufacturer. Concrete and grout shall conform to Section
03 30 00 CAST-IN-PLACE CONCRETE.
3.3 MANUFACTURER'S FIELD SERVICES
Furnish the services of an engineer or technician approved by the boiler manufacture for installation inspection,
startup, and tests of equipment as specified below. After installation of equipment the engineer or technician
shall provide a signed certificate or certified written statement that the equipment is installed in accordance
with the manufacturer's recommendations. Services of more than one engineer or technician may be required based
on types of specific equipment. One engineer or technician as appointed by the Contractor shall supervise and
be responsible for the overall installation, start-up, test, and check out of systems. This person shall remain
on the job until each unit has been in successful operation for 3 days and accepted.
3.4 BOILER CLEANING
Before being placed in service, boiler shall be boiled out for a period of 24 hours at a pressure not exceeding
83 kPa (gage) 12 psig. Solution to be used in the boiler for the boiling out process shall consist of two pounds
of trisodium phosphate per 379 liters 100 gallons of water. Upon completion of boiling out, flush out boiler
with potable water, drain, and charge with chemically treated water. Protect boiler and appurtenances against
internal corrosion until testing is completed and boiler is accepted. Professional services are required for
cleaning/treatment process.
3.5 FIELD QUALITY CONTROL
Perform and furnish everything required for inspections and tests as specified herein to demonstrate that boiler
and auxiliary equipment, as installed, are in compliance with contract requirements. Start up and operate the
system. During this time, clean strainers until no further accumulation of foreign material occurs. Exercise
care to minimum loss of water occurs when strainers are cleaned. Adjust safety and automatic control instruments
as necessary to place them in proper operation and sequence. During startup and during tests, factory-trained
engineers or technicians employed by individual suppliers of such components as the burner, flame safeguard and
combustion controls, and other auxiliary equipment shall be present as required, to insure proper functioning,
adjustment, and testing of individual components and systems. Test instrumentation shall be calibrated and have
full scale reading from 1.5 to 2 times test values.
3.5.1 Operational Tests
Operate each boiler and appurtenances prior to final testing and insure that necessary adjustments have been
made. Provide testing equipment required to perform tests. During this testing period, provide operating instructions
and training to persons tasked with operation of the boiler. Tests shall be accomplished with both fuel on duel
fuel units and include the following:
3.5.1.1 Preliminary Operational Test
Operate boilers continuously for a period of at least 8 hours to demonstrate proper operability of the combustion
control, flame safeguard control, and safety interlocks.
3.5.1.2 Acceptance Operational Test and Inspection
NOTE: Insert the appropriate Engineering Field Division.
Conduct a preliminary operational test prior to requesting an acceptance operational test and inspection by a
[_____] Division, Naval Facilities Engineering Command Boiler inspector. The Contracting Officer, upon receipt
of the notice from the Contractor, shall request the boiler be inspected by [_____] Division Naval Facilities
Engineering Command. Fifteen days advance notice is required for scheduling the inspector to conduct acceptance
operational test and inspection.
3.6 SCHEDULE
Some metric measurements in this section are based on mathematical conversion of inch-pound measurements, and
not on metric measurements commonly agreed on by the manufacturers or other parties. The inch-pound and metric
measurements shown are as follows:
Products Inch-Pound Metric
a. Pressure Gage
Diameter = 6 inches = 150 mm
b. Stack Thermometer
Scale Range = 150-750 degrees F = 66-399 degrees C
c. Alarm Bell
Diameter = 4 inches = 100 mm