1 Scope
NOTE This standard covers the design documentation, materials, installation, flushing, testing, and acceptance of private underground fire service mains and their appurtenances that convey water from an approved supply to the building fire protection systems, to private hydrants, and to fire department connections. (1.1)
NOTE A private fire service main is the buried piping, valves, fittings, hydrants, and thrust restraint located on private property between the point of service from the water supply and the point where the piping enters the building or connects to an aboveground system. (1.2)
NOTE The underground main is the single point of failure for every water-based fire protection system in the building, and once it is buried and backfilled its joints, restraint, and corrosion protection cannot be inspected without excavation. (1.3)
NOTE The scope extends from the point of connection at the public water main, the fire pump discharge, the storage tank, or other approved supply, through the buried main, the lead-in to the building, the control valves, the private hydrant laterals, and the buried piping serving the fire department connection, up to and including the connection to the system riser or the flange at the point of entry into the building. (1.4)
NOTE Thrust restraint, depth of cover, separation from other utilities, locating provisions, flushing, and hydrostatic acceptance testing are included as integral parts of the buried system. (1.5)
1.6 All work shall comply with NFPA 24, Standard for the Installation of Private Fire Service Mains and Their Appurtenances, in the edition adopted by the Authority Having Jurisdiction, together with the International Fire Code and the requirements of the water utility having jurisdiction over the point of connection.
1.7 Where the local water utility's standards or local amendments modify NFPA 24, the more stringent requirement governs unless the AHJ directs otherwise in writing.
1.8 The Contractor shall confirm the adopted edition of NFPA 24 and obtain the water utility's connection and backflow requirements before design begins.
NOTE Successive editions of NFPA 24 have refined the requirements for restrained joints, valve supervision, separation from other underground systems, and flushing flow rates, and the connection rules imposed by individual water utilities vary widely and frequently exceed the NFPA minimums. (1.9)
1.10 This standard does not govern the interior sprinkler or standpipe piping downstream of the point of entry, the fire pump and its room piping, or the public water distribution system upstream of the point of connection.
2 Referenced Standards
2.1 Materials, design, installation, and testing shall comply with the current adopted editions of the following standards.
NOTE Where standards conflict, the more stringent requirement governs unless the Engineer of Record directs otherwise in writing. (2.2)
| Standard |
Title |
| NFPA 24 |
Standard for the Installation of Private Fire Service Mains and Their Appurtenances |
| NFPA 13 |
Standard for the Installation of Sprinkler Systems (interface to the system riser) |
| NFPA 14 |
Standard for the Installation of Standpipe and Hose Systems (interface to standpipe supply) |
| NFPA 20 |
Standard for the Installation of Stationary Pumps for Fire Protection (interface to pump suction and discharge) |
| NFPA 22 |
Standard for Water Tanks for Private Fire Protection |
| NFPA 25 |
Standard for the Inspection, Testing, and Maintenance of Water-Based Fire Protection Systems |
| NFPA 291 |
Recommended Practice for Fire Flow Testing and Marking of Hydrants |
| IFC |
International Fire Code |
| ANSI/AWWA C150/A21.50 |
Thickness Design of Ductile-Iron Pipe |
| ANSI/AWWA C151/A21.51 |
Ductile-Iron Pipe, Centrifugally Cast |
| ANSI/AWWA C104/A21.4 |
Cement-Mortar Lining for Ductile-Iron Pipe and Fittings |
| ANSI/AWWA C111/A21.11 |
Rubber-Gasket Joints for Ductile-Iron Pressure Pipe and Fittings |
| ANSI/AWWA C110/A21.10 |
Ductile-Iron and Gray-Iron Fittings |
| ANSI/AWWA C153/A21.53 |
Ductile-Iron Compact Fittings |
| ANSI/AWWA C600 |
Installation of Ductile-Iron Mains and Their Appurtenances |
| ANSI/AWWA C900 |
Polyvinyl Chloride (PVC) Pressure Pipe and Fabricated Fittings, 4 In. Through 60 In. |
| ANSI/AWWA C605 |
Underground Installation of Polyvinyl Chloride (PVC) and Molecularly Oriented PVC (PVCO) Pressure Pipe |
| ANSI/AWWA C906 |
Polyethylene (PE) Pressure Pipe and Fittings, 4 In. Through 65 In., for Waterworks |
| ANSI/AWWA C509 / C515 |
Resilient-Seated Gate Valves for Water Supply Service |
| ANSI/AWWA C502 |
Dry-Barrel Fire Hydrants |
| ANSI/AWWA C503 |
Wet-Barrel Fire Hydrants |
| ASTM A674 |
Polyethylene Encasement for Ductile-Iron Pipe Systems |
| UL 262 |
Gate Valves for Fire Protection Service |
| UL 789 |
Indicator Posts for Fire Protection Service |
| UL 246 |
Hydrants for Fire Protection Service |
| FM Global |
Approval standards for fire service piping, valves, and hydrants |
3 Submittals
3.1 Action Submittals
3.1.1 The Contractor shall submit the following for the Engineer of Record's review and the Authority Having Jurisdiction's and water utility's approval prior to procurement and installation, as a coordinated package:
- Plan and profile drawings of the underground fire service main showing routing, pipe size, depth of cover, the point of connection, the location of every valve, fitting, hydrant, and the building lead-in, and the separation from other underground utilities
- Product data for pipe, fittings, joints, gaskets, valves, indicator posts, hydrants, and thrust restraint hardware, with the listing or approval mark for fire service components
- Pressure class data for the pipe and fittings, demonstrating that the selected class equals or exceeds the maximum system working pressure plus the required surge allowance at the depth of cover and trench loading conditions
- Thrust restraint calculations and details, identifying the restraint method at each bend, tee, cross, reducer, valve, hydrant lateral, and dead end, including restrained-joint length calculations or thrust block bearing areas
- Material certifications for the pipe, fittings, and gaskets, confirming compliance with the referenced AWWA standards
- Corrosion protection details, including polyethylene encasement or cathodic protection where required by the soil resistivity evaluation
☑ Plan and profile drawings with depth of cover and utility separation
☐ Product data for pipe, fittings, valves, indicator posts, hydrants, restraint
☐ Pressure class data with surge allowance
☐ Thrust restraint calculations and details
☐ Material certifications per AWWA standards
☐ Corrosion protection details (encasement / cathodic protection)
3.1.2 No underground work shall proceed until the corresponding submittals are reviewed, returned, and any required approval from the AHJ and the water utility is in hand.
3.1.3 The plan and profile drawings shall be prepared by or under the supervision of a person with qualifications acceptable to the AHJ.
NOTE Underground fire service main submittals are reviewed by both the AHJ and the water utility, and the water utility's connection requirements frequently govern the point of connection, the backflow arrangement, and the metering, so early coordination prevents rework. (3.1.4)
3.2 Closeout Submittals
3.2.1 The Contractor shall submit the following at completion before the underground fire service main is accepted:
- Contractor's Material and Test Certificate for Underground Piping (the NFPA 24 certificate), signed by the installing contractor, recording the pipe and joint materials, the thrust restraint, the flushing flow rate and duration, the hydrostatic test pressure and duration, and the measured leakage against the allowable
- As-built plan and profile drawings recording the actual routing, depth of cover, valve and hydrant locations, and any field changes, with locating information for the buried main
- Flushing certificate recording that each segment was flushed at the required rate until the discharge ran clear of debris prior to connection to the system risers
- Hydrostatic test certificate recording the test pressure, the two-hour hold, and the measured leakage
- Manufacturer warranty documentation for valves, hydrants, and other appurtenances carrying a manufacturer warranty
☑ Contractor's Material and Test Certificate for Underground Piping (NFPA 24)
☐ As-built plan and profile drawings with locating information
☐ Flushing certificate
☐ Hydrostatic test certificate
☐ Manufacturer warranty documentation
4 Quality Assurance
4.1 Installer Qualifications
4.1.1 The underground fire service main shall be installed by a contractor licensed and qualified to install private fire service mains as required by the state and local jurisdiction.
4.1.2 Where state law requires a fire protection contractor's license or a specific underground fire main certification, the installing contractor shall hold the current required credential.
4.1.3 The contractor performing the flushing, hydrostatic test, and connection to the system riser shall be the licensed fire protection contractor, even where a separate site utility contractor installs the buried piping.
NOTE Underground fire mains are frequently installed by site utility contractors under the same trench operation as domestic water and storm piping, but the responsibility for a code-compliant fire main and its acceptance testing remains with the licensed fire protection contractor. (4.1.4)
4.2 Listing and Approval
4.2.1 Valves, indicator posts, hydrants, check valves, and other appurtenances controlling or carrying water to the fire protection systems shall be listed or approved for private fire service main use by a Nationally Recognized Testing Laboratory or FM Global as accepted by the AHJ.
4.2.2 Pipe, fittings, and gaskets shall conform to the referenced AWWA standards and shall be approved for the working pressure and service conditions.
4.2.3 No component shall be substituted for a listed or approved product with an unlisted equivalent without the Engineer of Record's written approval and confirmation of acceptability by the AHJ.
4.3 Coordination with Site Utilities
4.3.1 The fire main Contractor shall coordinate the trench, depth, and routing with the site civil and utility trades so that the required separation from sanitary sewer, storm drainage, and other utilities is maintained.
NOTE Conflicts between the fire main and other underground utilities — especially sanitary sewer crossings — are a common cause of field changes that compromise depth of cover or separation if not resolved before excavation. (4.3.2)
5 Site and Service Conditions
5.1 Soil Corrosivity
○ None required - soil resistivity above the threshold for the pipe material
● Polyethylene encasement of ductile iron pipe per ASTM A674 / AWWA C105
○ Polyethylene encasement plus cathodic protection - aggressive soils
5.1.1 Where ductile iron pipe is installed in soils evaluated as corrosive, the pipe shall be protected by polyethylene encasement in accordance with ASTM A674 / AWWA C105, or by an equivalent listed corrosion control method.
5.1.2 A soil resistivity and corrosivity evaluation shall be performed where the corrosion potential is unknown, and the protection method shall be selected from the evaluation.
NOTE Ductile iron pipe corrodes externally in aggressive soils, and an unencased ductile iron fire main in corrosive soil can fail by graphitic corrosion years after installation, with the failure hidden until the main loses pressure or bursts. (5.1.3)
NOTE Polyethylene pipe materials such as PVC and HDPE are not subject to galvanic soil corrosion, which can make them preferable in aggressive soils where the pressure class and listing are otherwise satisfied. (5.1.4)
5.2 Frost Depth
0100
122436486072
Default: 36 in
Per drawings — site fire protection plan
5.2.1 The local frost depth shall be obtained from the AHJ or the local building department and shall govern the minimum depth of cover where it exceeds the standard minimum.
5.2.2 The fire main shall be buried so that the top of the pipe is not less than 1 ft below the local frost line, in accordance with NFPA 24.
NOTE A fire main that freezes is fully impaired, and freeze protection by depth of cover is the primary defense; in cold climates the frost-depth requirement, not the standard minimum cover, governs the trench depth. (5.2.3)
6 Pipe and Fittings
6.1 Pipe Material
NOTE The pipe material is selected based on the working pressure, the diameter, the soil corrosivity, the surge conditions, and the water utility's accepted materials. (6.1.1)
NOTE Each material has a defined application envelope, and the selected material shall be listed or approved for private fire service main use. (6.1.2)
Ductile iron, cement-mortar lined (AWWA C151 / C104)
PVC pressure pipe (AWWA C900)
HDPE pressure pipe (AWWA C906)
Per drawings — site fire protection plan
6.1.3 Ductile iron pipe shall conform to AWWA C151/A21.51, shall be cement-mortar lined in accordance with AWWA C104/A21.4, and shall be of the pressure class required by the working pressure and trench loading per AWWA C150/A21.50.
6.1.4 PVC pressure pipe shall conform to AWWA C900 and shall be installed in accordance with AWWA C605.
6.1.5 HDPE pressure pipe shall conform to AWWA C906 and shall be PE 4710 material of the dimension ratio required by the working pressure.
6.1.6 Where the water utility restricts the acceptable pipe materials at the point of connection, the utility's accepted material shall be used for the portion under the utility's jurisdiction.
NOTE Ductile iron is the predominant material for private fire service mains because of its strength, surge resistance, and broad acceptance by water utilities, but its external corrosion in aggressive soils requires encasement. (6.1.7)
NOTE PVC C900 is widely used for buried fire mains where its pressure class is adequate and the utility accepts it, and it is immune to soil corrosion, but it is more susceptible to damage from pressure surge and requires careful bedding and thrust restraint. (6.1.8)
6.2 Pressure Class
150 psi
200 psi
250 psi
300 psi
350 psi
Per drawings — site fire protection plan
6.2.1 The pipe pressure class shall be selected so that the rated pressure equals or exceeds the maximum system working pressure plus the surge allowance, evaluated at the depth of cover and trench loading conditions per AWWA C150 for ductile iron or the applicable design method for PVC and HDPE.
6.2.2 The pipe shall in no case be rated below the hydrostatic test pressure required at acceptance.
NOTE Selecting the pressure class on working pressure alone, without the surge allowance, is a common error; pressure surge from valve operation or fire pump start can transiently exceed the working pressure and govern the class. (6.2.3)
6.3 Lining
6.3.1 Ductile iron pipe and fittings shall be cement-mortar lined in accordance with AWWA C104/A21.4 unless a different listed lining is required by the water analysis.
NOTE The cement-mortar lining protects the interior of ductile iron pipe from tuberculation and maintains the interior diameter and the hydraulic capacity over the life of the main. (6.3.2)
6.4 Fittings
6.4.1 Fittings for ductile iron mains shall conform to AWWA C110/A21.10 or AWWA C153/A21.53 (compact fittings) and shall be of a pressure rating not less than that of the connected pipe.
6.4.2 Fittings shall be cement-mortar lined to match the pipe.
6.4.3 Fittings for PVC and HDPE mains shall be ductile iron or molded fittings listed or approved for the pipe material and the working pressure, joined by the method listed for the system.
7 Joints and Thrust Restraint
7.1 Joint Type
Push-on (rubber gasket) - straight runs
Mechanical joint - fittings, valves, and restraint locations
Restrained joint (proprietary or gland) - at thrust locations
Fused (HDPE only) - inherently restrained
Per drawings — site fire protection plan
7.1.1 Push-on and mechanical joints for ductile iron pipe shall use rubber gaskets conforming to AWWA C111/A21.11.
7.1.2 Restrained joints shall be used at every location where the line changes direction or terminates, and elsewhere as required by the restraint calculation.
7.1.3 HDPE pipe joined by butt fusion is inherently restrained and does not require separate joint restraint at fittings made up by fusion, but transitions to mechanical joints shall be restrained.
NOTE The push-on joint is the workhorse joint for straight runs and is fast to assemble, but it carries no longitudinal load and relies entirely on thrust restraint to resist the unbalanced forces at bends and ends. (7.1.4)
7.2 Thrust Restraint Requirement
7.2.1 Thrust restraint shall be provided at every bend, tee, cross, reducer, valve, hydrant lateral, plug, cap, and dead end, sized for the unbalanced hydrostatic force at the test pressure.
7.2.2 Thrust restraint shall be provided by restrained joints, thrust blocks, or a combination, selected for the soil bearing capacity, the working and surge pressures, and the available reaction area.
NOTE The unbalanced force at a fitting under pressure tends to push the fitting apart at the joint; without restraint the joint blows off, the main loses pressure, and the fire protection system is impaired, which is the single most consequential failure mode of a buried fire main. (7.2.3)
7.3 Thrust Restraint Method
● Restrained joints (calculated restrained length each side of the fitting)
○ Concrete thrust blocks bearing against undisturbed soil
○ Combination - restrained joints with thrust blocks at critical fittings
7.3.1 Where restrained joints are used, the restrained length on each side of the fitting shall be calculated for the soil type, the depth of cover, the pipe size, and the design pressure, and the restraint hardware shall be listed or approved for the pipe and the working pressure.
7.3.2 Where concrete thrust blocks are used, the bearing area shall be sized against the bearing capacity of undisturbed soil, the block shall bear against undisturbed trench wall, and the block shall be poured so that it does not encase the joint or the bolts.
7.3.3 Thrust blocks shall be cured before the main is pressure tested.
NOTE Restrained joints are preferred over thrust blocks in poor or disturbed soils, in congested trenches, and where future excavation near the main is anticipated, because a thrust block depends entirely on the bearing capacity of soil that may be disturbed by later work. (7.3.4)
NOTE Undersizing the restrained length or the thrust block bearing area is a common calculation error that passes the hydrostatic test but fails later under surge or under the higher pressure of a fire event. (7.3.5)
8 Valves and Supervision
8.1 Control Valve Arrangement
Post indicator valve (PIV) at least 40 ft from the building
Wall post indicator valve (PIVA) on the building wall
Indicating valve in a valve pit
Indicating valve at the backflow assembly at least 40 ft from the building
Per drawings — site fire protection plan
8.1.1 An indicating control valve shall be provided to isolate the fire service main, located and arranged in accordance with NFPA 24.
8.1.2 A post indicator valve shall be located not less than 40 ft from the building it serves, unless an exception of NFPA 24 permits a closer location.
8.1.3 The control valve shall be of the indicating type so that its open or closed position is visually evident without operating it.
8.1.4 A non-indicating buried gate valve, a curb stop, or any valve whose position cannot be confirmed without operating it shall not be substituted for the listed indicating control valve.
NOTE The 40 ft setback keeps the control valve operable and away from a building that is on fire or in danger of collapse, so that the supply can be controlled from a safe distance. (8.1.5)
8.2 Underground Gate Valves
8.2.1 Buried gate valves shall be resilient-seated gate valves conforming to AWWA C509 or C515, listed or approved for fire service, and shall open in the direction designated by the water utility.
8.2.2 Each buried gate valve shall be provided with a valve box extended to grade, or shall be installed in a valve pit accessible for operation, so that the valve can be operated and located after backfill.
8.2.3 The valve box shall be set plumb and centered over the operating nut and shall be supported so that backfill settlement does not transfer load to the valve.
8.3 Valve Supervision
● Electrical tamper switch to the fire alarm system (required where a supervised fire alarm system is present)
○ Locked open with chain and padlock (where electrical supervision is not required)
○ Sealed open with periodic inspection (where neither of the above is required)
8.3.1 Every control valve in the fire service main shall be supervised in the open position.
8.3.2 Where the building is provided with a supervised fire alarm system, the control valve shall be electrically supervised by a tamper switch that sends a supervisory signal to the fire alarm system within two turns of the valve operator from the fully open position.
8.3.3 Where electrical supervision is not required, the valve shall be secured open by an approved means such as a locked chain or seal subject to periodic inspection under NFPA 25.
NOTE A closed control valve is the leading cause of fire protection system failure during a fire, and supervision exists to detect a closed valve before a fire occurs rather than after. (8.3.4)
NOTE Tamper switch installation on the underground control valve requires coordination with the fire alarm Contractor and is a routinely missed connection on projects where the fire main and the fire alarm are installed by different trades. (8.3.5)
9 Hydrants and Fire Department Connections
9.1 Private Hydrants
● Dry-barrel hydrant (AWWA C502) - freezing climates
○ Wet-barrel hydrant (AWWA C503) - non-freezing climates
Per drawings — site fire protection plan
9.1.1 Private hydrants shall be listed or approved for fire service and shall conform to AWWA C502 (dry-barrel) or AWWA C503 (wet-barrel) as applicable to the climate.
9.1.2 Dry-barrel hydrants shall be used in climates subject to freezing, so that the barrel drains below the frost line when the hydrant is shut off.
9.1.3 Each hydrant shall be provided with an auxiliary control valve on the hydrant lateral so that the hydrant can be isolated for maintenance without shutting down the main.
9.1.4 Hydrant outlet threads shall match the local fire department's hose threads and shall be confirmed with the AHJ.
NOTE A wet-barrel hydrant in a freezing climate retains water in the barrel and will freeze and crack, rendering it inoperable in the season it is most needed, which is why the dry-barrel design is required where freezing occurs. (9.1.5)
9.2 Hydrant Location and Marking
9.2.1 Private hydrants shall be located, spaced, and marked as required by the AHJ and the IFC, and shall be accessible to fire apparatus and free of obstruction.
9.2.2 Hydrants shall be set so that the outlets are at the height above grade required by the AHJ and the hydrant is plumb.
9.2.3 Hydrant flow capacity and residual pressure shall be verified by a flow test in accordance with NFPA 291 after the main is in service.
9.3 Fire Department Connection Supply
9.3.1 Where the fire department connection is supplied through the underground fire service main, a listed check valve shall be installed in the fire department connection piping so that water pumped into the connection cannot flow back into the main.
9.3.2 A control valve shall not be installed in the piping between the fire department connection and its point of connection to the fire service main.
9.3.3 The buried piping serving the fire department connection shall be drained automatically so that water does not accumulate and freeze in the connection in cold climates.
NOTE Installing a control valve in the fire department connection supply piping would allow that valve to be inadvertently closed, defeating the fire department's ability to boost the system, which is why NFPA 24 prohibits it. (9.3.4)
10 Depth of Cover and Separation
10.1 Depth of Cover
3096
3642486072
Default: 48 in
Per drawings — site fire protection plan
10.1.1 The fire service main shall be buried so that the depth of cover to the top of the pipe is not less than the greater of the local standard minimum, 1 ft below the local frost line, or the depth required to protect the pipe from the surface loading at the location.
10.1.2 Where the main crosses under a roadway or other area of vehicle loading, the depth of cover and the pipe class shall be confirmed adequate for the live load.
NOTE Insufficient cover exposes the main to freezing and to crushing loads, and is a recurring deficiency where the trench depth is reduced to avoid a conflict with another utility. (10.1.3)
10.2 Separation from Other Utilities
Per drawings — site fire protection plan
10.2.1 The fire service main shall maintain the horizontal and vertical separation from sanitary sewer, storm drainage, and other underground utilities required by the AHJ, the water utility, and the local health code.
10.2.2 Where the fire main must cross a sanitary sewer, the crossing shall maintain the required vertical separation and the fire main shall be located above the sewer, or the sewer shall be sleeved or constructed of pressure-rated pipe across the crossing, as required by the health authority.
NOTE A fire main carries water that may be drawn into the building potable system through the fire protection connection, so cross-contamination from a nearby sewer is a public-health concern, and the separation requirement is enforced by the health authority in addition to the fire code. (10.2.3)
10.3 Locating Provisions
10.3.1 A continuous tracer wire or an approved equivalent locating means shall be installed along non-metallic fire service mains (PVC and HDPE) so that the buried main can be located after backfill.
10.3.2 The tracer wire shall be brought to grade at valve boxes or other accessible points so that a locator can energize it.
NOTE A buried non-metallic main with no tracer wire cannot be located by ordinary utility locating equipment, and an unlocatable fire main is at risk of being struck during future excavation. (10.3.3)
11 Installation
11.1 Trench and Bedding
11.1.1 The main shall be installed in accordance with AWWA C600 for ductile iron, AWWA C605 for PVC, and the manufacturer's instructions for HDPE.
11.1.2 The pipe shall be laid on a firm, continuous bedding free of rock and debris, and the bedding and haunching material shall be placed and compacted so that the pipe is uniformly supported.
11.1.3 The trench shall be dewatered during pipe laying so that joints are made in the dry and the pipe is not floated off the bedding.
11.2 Joint Assembly
11.2.1 Joints shall be assembled in accordance with the pipe and joint manufacturer's instructions, with gaskets clean and lubricated as specified and the pipe inserted to the full joint depth.
11.2.2 Restrained joints and restraint hardware shall be assembled and torqued in accordance with the manufacturer's instructions.
11.2.3 The interior of the pipe shall be kept clean and free of debris during installation, and open pipe ends shall be plugged when work is not in progress.
11.3 Backfill
11.3.1 Backfill shall not be placed over joints until any required visual inspection of the joints and the thrust restraint has been completed.
11.3.2 The pipe may be center-loaded with backfill to prevent uplift during testing while the joints remain exposed for inspection, in accordance with NFPA 24.
11.3.3 Backfill shall be placed and compacted in lifts so that the pipe is not displaced and the required cover is achieved without voids.
NOTE Burying joints and thrust restraint before inspection forfeits the only opportunity to verify the buried system, and NFPA 24 requires the joints to remain exposed for the acceptance inspection for this reason. (11.3.4)
12 Flushing
12.1 Flushing Requirement
12.1.1 The underground main and the lead-in to the building shall be thoroughly flushed before the connection to the system riser or other aboveground fire protection piping is made.
12.1.2 Flushing shall be performed at a flow rate that produces a velocity of not less than 10 ft/s in the main, or at the maximum flow rate available, in accordance with NFPA 24.
12.1.3 Flushing shall continue until the discharge runs clear of debris.
NOTE Debris left in the underground main — gravel, soil, tools, or construction debris — will be carried into the sprinkler system at the first flow and can plug sprinklers, alarm valves, and fire pump components, which is why flushing before connection is mandatory and is verified at acceptance. (12.1.4)
12.2 Flushing Sequence
12.2.1 Flushing shall be completed and witnessed before the underground main is connected to the system riser.
12.2.2 The flushing flow rate and the duration shall be recorded on the Contractor's Material and Test Certificate.
NOTE Connecting the main to the riser before flushing transfers any debris in the main directly into the building system, a defect that is expensive to correct after the system is closed up. (12.2.3)
13 Hydrostatic Testing and Acceptance
13.1 Hydrostatic Test
200350
200225250300350
Default: 200 psi
Per drawings — site fire protection plan
13.1.1 The underground main and its appurtenances shall be hydrostatically tested at not less than 200 psi, or at 50 psi in excess of the maximum system working pressure where that pressure exceeds 150 psi, whichever is greater, in accordance with NFPA 24.
13.1.2 The test pressure shall be maintained within a gauge pressure of ±5 psi for a period of two hours.
13.1.3 The thrust restraint shall be in place and any thrust blocks shall be cured before the test is applied.
13.1.4 The test shall not be applied until any required visual inspection of the joints and restraint has been completed.
13.2 Leakage Acceptance
13.2.1 Leakage during the hydrostatic test shall not exceed the allowable leakage determined by the NFPA 24 formula, in which the allowable leakage in gallons per hour equals the length of pipe tested in feet multiplied by the nominal pipe diameter in inches multiplied by the square root of the average test pressure in gauge psi, divided by 148,000.
13.2.2 Where the measured leakage exceeds the allowable, the leaking joints shall be located and corrected and the segment shall be retested until the leakage is within the allowable.
NOTE The allowable leakage formula recognizes that gasketed joints weep slightly under test, so the acceptance criterion is a calculated allowable rather than zero leakage; a visible leak at a single joint, however, shall be corrected regardless of the total measured leakage. (13.2.3)
13.3 Forward Flow and Final Acceptance
13.3.1 Where a backflow preventer is installed on the fire service main, a forward flow test shall be performed to confirm that the assembly passes the system demand flow without excessive pressure loss.
13.3.2 Final acceptance shall not be granted until the flushing, the hydrostatic test, the leakage verification, and the forward flow test (where applicable) are complete and recorded on the Contractor's Material and Test Certificate.
13.3.3 The completed and signed Contractor's Material and Test Certificate for Underground Piping shall be submitted to the AHJ as the record of acceptance.
14 Delivery, Storage, and Handling
NOTE Pipe, fittings, gaskets, valves, and hydrants shall be delivered, stored, and handled in accordance with the manufacturer's instructions and the referenced AWWA standards. (14.1)
14.2 Pipe and fittings shall be stored off the ground and protected from damage, and the interior shall be kept clean and free of debris.
14.3 Gaskets shall be stored out of direct sunlight and away from heat, ozone sources, and petroleum products, which degrade rubber over time.
14.4 PVC and HDPE pipe shall be protected from prolonged ultraviolet exposure during storage, which embrittles the material over time.
14.5 Pipe shall be inspected for damage before installation, and damaged pipe, cracked fittings, or pipe with damaged linings shall not be installed.
15 Warranty
15.1 The Contractor shall warrant the underground fire service main installation against leaks, joint failures, thrust restraint failure, and defects in workmanship for a period of not less than one year from acceptance, or for the period stated in the contract documents if longer.
15.2 Any leak, joint separation, or restraint failure occurring within the warranty period, and any resulting excavation, repair, retest, and site restoration, shall be corrected at the Contractor's expense.
NOTE Because the main is buried, a warranty repair entails excavation and site restoration in addition to the pipe repair, and the Contractor's warranty shall extend to the full cost of restoring the disturbed surface. (15.3)