Chilled Water Bridge
Where size for a pipe segment is not indicated, the pipe segment size shall be equal to the largest pipe segment to which it is connected. Transition to smaller size shall occur on the side of fitting where smaller size is indicated.
All pipe, valves, fittings and pumps shall be installed as indicated on the drawings and according to the manufacturer’s instructions and installation drawings. All welding shall be performed to meet ASTM B31.1 unless noted by designer as otherwise.
General Locations and Arrangements Drawings (plans, details, schematics, and diagrams) indicate the general location and arrangement of the piping systems. Location and arrangement of piping layout shall take into consideration pipe sizing, friction loss, pump sizing, maintenance accessibility and other design considerations. So far as possible, install piping as indicated.
- Performed a minimum of three (3) institutional building piping installations within the last 5 years.
- Has been in the institutional building piping business and has been performing this type of work for a minimum of 5 years.
- Is licensed to perform work in the State of North Carolina.
- Pipe: ASTM/ANSI number, grade if known, class, type, wall thickness, material.
- Fittings: ASTM/ANSI number, grade if known, class, type, wall thickness, material.
- Flanges: ASTM number, grade, class, type, material.
- Isometric drawings showing routing, sensor location, valve location and hanger locations.
- Test Pressure and media.
- Pipe cleaning method.
- Valves: manufacturer cut sheets, size, materials, actuator size, pressure rating.
- Pumps: manufacturer cut sheets, pump curves, including design capacity and head, motor cut sheets, pump base design, pump installation requirements, pump manufacturers alignment specifications, flexible coupling design and cut sheet.
- Welder certifications.
- Thermometer: manufacturer cut sheet, size, range.
- Information for (TCV-A) Return Temperature Control Valve
- Alternate (TCV-A) Return Temperature Control Valve
Manual Utility and Building Isolation Valves
Use high performance butterfly valves. The valve shall have a lugged wafer style body of carbon steel or ductile iron rated for ANSI class 150 service. The seat material shall be fluoropolymer-based blend with no fillers, nor PTFE filled. Disk and shaft shall be 316 Stainless Steel construction. Shaft shall be full-length. Stub shafts are NOT allowed. Disk to shaft connection shall be non-shear tangential pinning. Disk shall be offset from the shaft centerline. The valve shall have upper and lower shaft bushing/bearings of a 316 stainless steel carrier and PTFE liner. Shaft seal shall be multiple rings of V-flex style PTFE packing with 316 stainless steel packing- ring.
Approved Manufacturers: Jamesbury, Milwaukee, or approved equal
Pump Isolation Valve
Valves shall be full lug type permitting removal of downstream piping while using valve for system shut-off. Bi-directional dead-end pressure rating to be a minimum of 150 psig with no downstream flange/piping attached. Standard applications shall use 10-position lever operators for valve sizes 5” and smaller, gear operator for larger sizes.
Approved Manufacturers: Nibco, Apollo, Milwaukee, Jamesbury, or approved equal
Install butterfly valves as shown on plans, details and according to valve manufacturer’s installation recommendations.
Valves may be used to facilitate the fit-up of weld neck flanges, but the valve must be removed before the flanges are welded. During fit-up, metal pancakes or solid pieces of gasket material shall be used to ensure that valve is not damaged from sparks or spatter.
Valves with gear operators or actuators are to be installed with stems at or above centerline wherever possible, but in no case with the stems straight down. Valves with actuators and position indicators shall be installed so that the indicator is visible from the floor. Any valve installed with reducers nearby must have appropriate spacing to remove any bolt without pipe disassembly.
Before tightening flange bolts, adjust the disc of the valve to the full-open position. Tighten bolts to specification in crisscross pattern. After tightening, rotate disc to closed position to assure proper operation.
After piping systems have been pressure tested and put into service, but before final adjusting and balancing, inspect valves for leaks. Adjust, replace packing or replace valves to stop leaks.
Provide gear operator for manually operated butterfly valves 6” and larger.
Chain Wheel Operators
Provide chain operators for manually operated butterfly valves 6” and larger, located more than 8 ft. above equipment room floor.
Cast iron or ductile iron adjustable sprocket rims and chain guides are required. Use galvanized or brass chain and chain closure links to form continuous loop of chain at each operator.
Ball valves for use in chilled water systems must have a performance rating of CWP 600psi with two (2) piece design. Provide valve neck extensions of sufficient length to allow for insulation. Three (3) piece valves are NOT allowed.
Approved Manufacturers: Apollo 70-100 series or approved equal
Check valves used for Duplex pump system should be 150 Class Dual Disc Wafer Style. Check Valves for the Pump Bypass should be 150 Class flanged swing check.
Thread-o-lets must be used at vent and drain connections, thermowells and/or other instrument locations. Materials of Weld-o-lets® and Thread-o-lets® shall match the material of the piping. All holes shall be made with a drill bit or hole saw. Holes may NOT be cut with a torch.
Reducers in horizontal piping shall be the eccentric type with the top level. Reducers in vertical piping shall be concentric. All reducers must be installed to allow bolt installation and removal after all equipment is in place.
Provide drain valves at all low points and vents at high points of piping systems (even if not shown on drawings) for complete drainage of systems. This includes, but is not limited to, all low points, bases of all risers, at each branch take-off and between isolation valves. See drain and vent sizing chart on the next tab.
All Chilled Water piping lines shall be seamless, standard weight, Schedule 40 black steel ASTM A53 GR B. Chilled Water pipes larger than 2” shall have welded joints. Threaded nipples shall be Schedule 80 black steel.
Pipe fittings shall be standard weight Schedule 40 black steel. Use only long radius elbows.
ASTM A105, ANSI B16.5, hot forged steel, weld neck pattern flanges are to be used whenever possible. Slip-on flanges are not allowed without Chilled Water Director’s prior consent. Bore dimension of weld neck flange shall match inside diameter of connected pipe. Full face gaskets must be used with flat face flanges, and ring-type gaskets must be used with raised face flanges. For example, pump connections and strainers. Valves may be used to facilitate the fit-up of flanges; but valves must be removed before the flanges are welded. During fit-up, metal pancakes or a solid piece of gasket material shall be used to ensure that the valve is not damaged from weld sparks or weld splatter while tacking flanges.
Bolts and nuts shall be Grade 5 NC. Bolts, bolt studs, nuts and washers shall have zinc/cadmium plate finish. Note: Threaded rods are not allowed as fastening elements. If studs are to be used, they are to be individually factory stamped with grade identification.
Provide drain valves at all low points and vents at high points of piping systems (even if not shown on drawings) for complete drainage and venting of systems between isolation valves and elsewhere as noted on flow diagram, plans and details. Where the vent lines cannot be reached from floor level, or be easily reached using an 8’ ladder, the vent lines shall be run with a second isolation valve accessible from floor level and the discharge to be run to the sanitary sewer system.
Connections to the pipe shall be made using thread-o-lets and Schedule 80 nipples. For drains and vents, provide ball valves of type specified above and size specified below with hose thread adapter and cap.
|Pipe Size||Drain Size||Vent Size|
|6” and less||Minimum ¾”||Minimum ½”|
|8” to 10”||Minimum 1”||Minimum ¾”|
|12” to 14”||Minimum 1¼”||Minimum ¾”|
|16” and greater||Minimum 2”||Minimum ¾”|
Differential Pressure Sensor/Transmitters
Thread-o-lets® are to be used for differential pressure sensor/transmitters. Taps are to be a minimum ½” with ½” valve reduced down to 3/8”. Taps should be on the side of the horizontal run pipe at the three o’clock or nine o’clock position to avoid sediment and/or air trapping. After the valve, lines shall be run in a manner so as not to trap air. Compression fittings allowed only at the transmitter and isolation valves. Isolation valves to be ball valves installed at DP taps. The tubing for differential pressure instrument shall be installed with continuous runs from isolation valve to transmitter connection.
Pump/Strainer Differential Pressure Gauge
Provide a single pressure gauge connected to both sides of strainers, pump suction, pump discharge, and pump discharge after check or balancing valve (whichever is farthest downstream). Gauge is not to be connected to the system through a manifold system where each branch can be isolated, and pressure relieved from the gauge. Thread-o-lets® are to be ½” when connecting to pump piping.
Approved Manufacturer: Weksler or other approved equal
Compressed air tubing must be copper or stainless steel from isolation valve to instrument or control valve. Tubing shall be run in a manner that will not promote trapping of water. Each end-user of compressed air shall have individual isolation valves and control valves with positioners, which shall have filters and separators with fully automatic drains. Compressed air lines must be sized for all components using their delivery rates. Branch lines shall be 3/8” minimum with no more than five (5) feet from the isolation valve to the pressure set or solenoid. If more than two (2) components are being served, the main line size should be run to the last component served.
Install two (2) thermometers, two (2) temperature sensors, flow meter, pressure differential transmitter with local digital readout and remote pressure differential transmitter as per flow diagrams between the four (4) bridge isolation valves.
Unless otherwise indicated, welding shall be done using only the following processes:
- Shielded Metal Arc Welding (SMAW), also known as “stick” welding
- If approved, Gas Tungsten Arc Welding (GTAW), also known as “TIG” and Heliarc welding.
For any welding performed after the pipe cleaning is completed, “TIG” welding is required. For repairs and replacement of existing pipe, pipe will be hand cleaned prior to installation and root pass will be installed using “TIG” process. This is for small sections of piping and repairs.
Backing rings (chill rings) or consumable inserts are not allowed, unless specifically requested by Owner and/or Engineer.
Ground clamp must be placed as close as possible to work, to ensure no damage to electronic equipment in this system or elsewhere in the mechanical room.
Repair any welds not meeting the acceptance criteria at no cost to the Owner.
Hanger and Support Spacing
Space pipe hangers and supports for steel pipe in accordance with the following schedule, with exceptions as indicated herein:
|Pipe Size||Max Spacing|
|Up through 1 ¼”||7’-0”|
Spacing less than indicated above may be required to conform with building structure design and/or loading limitations. If pipe size changes between support points, maximum spacing shall be based on the smaller pipe size. Install hangers and supports to bear on outside of insulation. Place hangers and supports within one (1) foot of either side of each fitting, such as elbow and tee, each valve, strainer, and other piping specialty for piping 4” and above.
Hanger Rods (Metallic)
Rods shall have electro-plated zinc or hot dipped galvanized finish.
Bolts, Nuts, Studs and Washers
Bolts, nuts, studs and washers shall have electro-plated zinc or hot dipped galvanized finish.
Support all piping from building structural members using beam clamps, ceiling plates, wall brackets, or floor stands. At no time shall hangers and supports overload building structural members. Fasten ceiling plates and wall brackets securely to structure and test to demonstrate adequacy of fastening.
Coordinate hanger and support installation to properly group piping of all trades.
Suspend hangers by means of hanger rods. Perforated band iron or flat wire (strap iron) is not allowed.
Piping shall not be supported by other piping, ductwork, or conduit.
Pipe hangers or supports are not allowed to penetrate vapor barrier of pipe insulation.
Install adequate supports during erection of piping so as not to over stress either piping or equipment to which piping is connected.
- Expanded Polyisocyanurate Foam is a continuously molded rigid foam insulation meeting requirements of ASTM C-591, with thermal conductivity of not more than 0.19 at 75°F mean temperature, minimum density of 2 lb/ft3, minimum compressive strength of 24 psi, maximum water vapor transmission of 4.0 perm-inch, and suitable for temperature of +300°F down to -297°F. Insulation shall have a factory- applied jacket with self-sealing lap (SSL). HiTHERM HT-300 or approved equal.
- Phenolic Foam insulation by ITW Trymer® Supercel Phenolic, Dyplast DyTherm® Phenolic or Resolco Insul-Phen® is an acceptable substitute provided insulation characteristics equal or exceed requirements specified for polyisocyanurate above.
- Saran Vapor Retarder Film™ with self-sealing (SSL), ASTM C-755 and C-1136, 6 mil thickness. Permeance shall not exceed 0.01 perms, equal to Dow™ Saran 560. Elbows, fittings, valves, and butt joints shall be wrapped with three (3) layers of Dow™ Saran 520 Vapor Retarder tape.
- Provide PVC jacket over Dow™ Saran tapes for exposed elbows, fittings and valves.
Install all products with good workmanship, smooth and even surfaces. Use full-length factory furnished material where possible. No scrap piecing is allowed. Apply insulation only on clean, dry surfaces after all rust and scale have been removed and hydro testing has been completed.
Pipes 1-1/2” and smaller, specified pipe insulation and vapor barrier with jacket shall be continuous through hanger or support locations and protective shields shall be provided to protect insulation from compressing or being crushed.
Pipe 2” and larger, where manufactured pre-insulated pipe supports are used at hanger or support locations, extend insulation and vapor barrier to insulated pipe supports. Use 3” wide vapor barrier tape at pipe support. Contractor shall be responsible for continuity of vapor barrier at insulated pipe supports.
Piping 6” or larger shall use 1-1/2” insulation. Below 6”, the insulation shall be 1”.
Contractor fabricated anchors, secure insulation directly to pipe surface and extended from insulated pipe four (4) times insulation thickness. For pre-insulated anchors, cover entire surface of anchor with elastomeric foam insulation (Armaflex or equal). Take special care to assure a good vapor seal at anchor.
Markers to comply with ANSI A13.1 for color, length of color field and include flow directional arrows integrated into the marker.
For insulated pipe systems, lettering sizes are as follows:
- Pipes up to 1 inch: use 1-inch letters
- Pipes 1-1/4” to 2 inches: use 2-inch letters
- Pipes 2-1/2” to 6 inches: use 3-inch letters
- Pipes over 6 inches: use 4-inch letters
Pipe identification labels shall be abbreviated as follows:
|Piping System||Identification||Paint Color|
|Chilled Water Supply||CHS||Rustoleum Blue 925 Safety|
|Chilled Water Return||CHR||Rustoleum Blue 866 Marlin|
|Condenser Water Supply||CWS||Sherwin Williams Green 4085 Safety|
|Condenser Water Return||CWR||Sherwin Williams Green MC25 Marsh|
Conduct pressure test prior to flushing and cleaning of piping systems. No systems shall be fully insulated until it has been successfully tested. Prior to the test being completed, insulation can be installed if it does not cover welds, joints, fittings or penetrations.
Conduct hydrostatic (HYDRO) test at 150psig with test medium of water unless otherwise indicated. For hydrostatic tests, remove air from piping being tested by means of air vents. If outlets are not available at high points, the Contractor shall make the necessary taps at points of highest elevation before the test is made.
The testing of the system shall be performed by a contractor experienced in pipe testing. The Contractor shall perform all phases of testing. S/he will provide supervision, pumps, calibrated gauges, instruments, test equipment, temporary piping and personnel required for tests, removal of test equipment and draining of pipes after tests have been successfully conducted.
Contractor should perform preliminary pressure test prior to witnessed record test to verify system will pass record test on first attempt. Pressure test may be made of isolated portions of piping systems to facilitate general progress of installation. Any revisions made in piping systems require re-testing of affected portions of piping systems. No pressure drop shall occur during test period. Any pressure drop during test period indicates leakage. If leaks are found, repair with new materials and repeat test; caulking or “JB Weld” is not acceptable.
Measure and record test pressure at high point in system. Where test pressure at high point in system causes excessive pressure at low point in system due to static head, portions of piping system may be isolated and tested separately to avoid undue pressure. However, every portion of piping system must be tested at the specified minimum test pressure.
Minimum test time shall be four (4) hours plus such additional time as Chilled Water Engineer may require insuring there are no air pockets in line, no broken pipe or defective materials in the line and no leaking joints.
Repair system and retest all portions of system when equipment or systems fails to meet minimum test requirements.
Submit results of each test for review to Engineer within three (3) days of test occurrence.
- Performed a minimum of three (3) institutional pipe cleanings within the last 5 years,
- Employed in the chemical pipe cleaning or treatment business, performing this type of work for a minimum of five (5) years,
- Licensed to perform work in the State of North Carolina.
Submit the following information:
- Detailed plans on performing the flushing and cleaning. The plan must include a strainer with opening no larger than 0.125 inches. The strainer will be removed several times during the process for inspection.
- Chemicals, description of chemicals, their composition and function
- Safety Data Sheets (SDS) for all chemicals to be used for pipe cleaning must be submitted to the Owner, including written notice of Owner’s responsibility to notify their employees of the use of those chemicals.
- Materials of construction
- Dimensions and weights
- All other appropriate data
Approved Chemical Manufacturers: Nalco or approved equal
The Contractor shall install temporary piping to facilitate the flushing at the ends of piping runs. The temporary piping should be line size, but no less than 1/3 main line size depending upon location. The temporary piping will be installed off the bottom of the permanent piping, top take offs will not be allowed for flushing and cleaning. This will ensure that all foreign material is removed during cleaning. If horizontal connection is required for cleaning it must be line size and any reducers must be eccentric with the flat install on bottom edge of piping.
The Contractor shall bypass all necessary equipment and sensitive components. The Contractor shall verify all lines being flushed are open with no strainers or filters in any line.
Contractor to flush and clean all new chilled water piping systems after the system has been successfully pressure tested. Chilled Water personnel shall witness the flushing and cleaning procedures. The Contractor shall provide all water for flushing and cleaning. Flushing water and cleaning solutions shall be discharged to the sanitary sewer system.
Install temporary strainer. Strainer is to protect pump(s) and collect debris and foreign material.
Verify the strainer is clean before proceeding. Fill the system with water, vent and add recommended amount of cleaner. The cleaner should be diluted by at least a 3:1 ratio to prevent excessive attack on metal surfaces at the point of application. (Do not allow any chemicals to contact galvanized surfaces).
Circulate system for a minimum of 24 hours at the flow rate recommended by the chemical manufacturer. Remove the temporary mesh strainer and debris. If temporary mesh strainer was not clean, reinstall and continue cleaning.
If UNC Construction Management representative determines the temporary mesh strainer is clean, completely drain the system and continue to next step.
Fill system with clean water, vent and circulate for one (1) hour. Drain system.
If installed, remove the temporary piping and pump. If building chilled water pumps were used, commence inspection and seal replacement with pump manufacturer’s service representative. After pump is inspected, realign and have alignment verified. Re-inspect for leakage.
Pumps shall have a minimum clearance of 24” on sides and ends of pumps and motors to allow access for service and repair. Pumps shall have isolation valves to allow removal of pumps for repair. Pumps shall have bled valves and gauge ports at accessible locations. All pumps shall be serviceable without removing the volute from piping connections. Pumps shall meet or exceed operating efficiencies scheduled.
Furnish pumps complete with premium efficiency inverter-duty, motors, drive assemblies, coupling guard where required and accessories as specified. Select motor with sufficient horsepower rating for non-overloading operation over entire pump curve.
Furnish each pump and motor with name plate giving manufacturer’s name, pump serial number, pump capacity in GPM and head in feet at design condition, horsepower, voltage, frequency, speed, and full load current. Hydraulic testing of all pumps should be pressure tested at 150% of rated pressure, clean and painted before shipment. Manufacturer shall certify all pump ratings and contractor will supply performance information as part of the submittals.
All pumps shall operate without objectionable noise or vibration with maximum noise level of 85 dBA.
Furnish one (1) set of seals and bearings for each new pump to Owner.
Casings shall be cast iron having a minimum tensile strength of 35,000 psi. Removal of impeller or rotating assembly shall be accomplished without disconnecting suction and discharge piping. Casings to have tapped and plugged openings for vent, drain, and suction and discharge gauge connections.
Impellers to be made of cast bronze, hydraulically and dynamically balanced, keyed and locked to pump shafts with replaceable shaft sleeves. Rotating elements shall be mounted in heavy-duty ball bearings (greaseable preferred) and shall be equipped with water slingers on the side next to pump glands.
Chilled water pumps to be furnished with single inside, unbalanced mechanical seals with carbon rotating faces, ceramic stationary seats, Buna-N elastomer and 316 SS metal hardware, such as a John Crane Type 1 Seal or equivalent, rated up to 225°F continuous operation.
If pumps are supplied with couplings, drop-out spacer type couplings with flexible neoprene sleeves are to be used to allow for pump servicing. Diaphragm couplings may be used with high horsepower pumps.
Pumps shall be supplied with the groutable steel base plates with stainless steel drip pans under the pump assembly with threaded drain connections, to be field routed during installation. Provide drain pan constructed of 16-gauge stainless steel, all welded under pump heads and inlet/outlet flanges, including flanges of connection pipe. Drain pan shall be sized to accommodate entire pump head area from flange to flange. Provide silicone sealant between pump feet and drain pan to make pan leak-proof. Provide ½” drain opening in drain pan to be extended to nearest floor drain during the installation.
Inline pumps may be used in situations not allowing for base mounted pumps. The motors for inline pumps must not exceed 5 HP (unless approved by Chilled Water Director) and the pumps must be independently supported from the piping, either to the floor or from a wall structure.
Approved Manufacturers: Allis Chalmers, Aurora, Peerless, PACO, Worthington, Flowserve, Dresser-Rand, Bell & Gossett or other approved equal
Motors driven by variable frequency drives (VFD) shall comply with the latest NEMA MG-1 Section IV, Part 31 unless otherwise noted and shall be inverter duty type. Starter insulation shall be designed to operate under maximum voltage peak of not less than 1600 volts with time reset not greater than 0.1 micro-seconds. Motor shall have corona resistant stator insulation. Motors shall be rated for 90°C temperature rise with 40°C ambient.
Motors shall have a 1.15 service factor in 40°C maximum ambient temperature. Select motors so they do not exceed nameplate rating nor operate into service factor to meet specified duty.
Motors shall have totally enclosed fan enclosures.
Motors shall have greaseable ball bearings with ANSI/AFBMA L-10 rating of 200,000 hours.
Motor vibration shall not exceed 0.15 inch per second, unfiltered peak.
All motors driven by VFDs shall be grounded as specified:
- Mechanical contractor shall provide shaft grounding ring (AEGIS SGR or equal) on motor shaft. Soft carbon brushes are not acceptable. Install per
manufacturer’s written instructions.
- The electrical contractor shall bond motor casing to local structural steel with braided straps of bare flat copper conductor cable, width to be specified by designing engineer.
- The electrical contractor shall bond motor feeder equipment grounding conductor to the motor terminal box. The contractor shall make sure to clean and prepare paint so that the connection for the ground will be clean and permanent. (Pertains to ALL motors)
Set base mounted pumps on concrete bases (housekeeping pad), or concrete inertia base. The concrete pads must be dowelled to the floor at 12-inch intervals and have one mat of ¼” rebar to provide the base strength. Hold down bolts must penetrate the housekeeping pad and go into the existing floor pad a minimum of 5 inches. Level the base and bolt down prior to grouting. Fill entire base with non-shrinking grout. Use end caps during the grouting to prevent overflow when end caps are not integral with base plates. Housekeeping pad may be extended to allow for suction diffuser support.
Install all pumps in strict accordance with manufacturer’s instructions to avoid any stress and misalignment. Piping connections to pumps shall not create stress on pump casing. After final connections are completed, the contractor shall remove the bolts from the flanged connections at pumps. Piping shall remain aligned with pump connections after all bolts have been removed. If piping becomes misaligned after bolts have been removed, or if bolts cannot be removed by hand, the contractor shall revise piping to align piping with pump connection. If after completion of the strain free verification the piping system must be disassembled at any point in the future, the strain free verification shall be repeated. During final assembly after successful test the gaskets shall be replaced.
Contractor shall employ a technician certified by the selected pump manufacturer to field align flexible coupled pumps after the base has been grouted, the pipe/pump alignment check and flushing and cleaning procedures have been completed. Align pump and motor in all four planes: vertical angular, horizontal angular, vertical parallel, horizontal parallel. Alignment shall be within the recommended value by pump manufacturer (not coupler manufacturer), but not over 0.002” parallel and 0.003” angular per radius inch. Record and submit all results of alignment procedure to Engineer. Soft foot measurements must be less than 0.005” on each foot.
Contractor shall produce a copy of the pump manufacturer’s alignment specifications (not pump coupler manufacturer’s specifications) at the time of Chilled Water verification or with pump submittals.
Where pump connection size and indicated line sizes are not identical, provide necessary concentric reducers/increasers for vertical piping at pump connection and eccentric reducers/increasers for horizontal piping at pump connection. Install eccentric reducers/increasers with top of pipe level. All isolation valves and flexible connections are to be full line size.
To perform pump startup:
- Verify that piping system has been tested, flushed, cleaned and filled.
- Verify that pipe/pump alignment has been verified by UNC Chilled Water representative.
- Verify that pump/motor alignment has been independently verified by UNC Chilled Water representative.
- Verify the VFD has been certified, with UNC Chilled Water technician present.
- Verify pump rotation.
- Prime pump and vent air from casing.