Section 33 63 13: Underground Steam and Condensate Distribution Piping
All new underground steam and condensate distribution system required as part of the project shall be designed and installed in accordance with all applicable codes and regulation.
The University will provide a site survey, tied to the University’s survey control network, along the proposed routing of the distribution system. The site survey will include the identification, location, and depth of all existing underground utilities and structures as well as all aboveground utilities, roadways, structures, etc. The survey will be made after the general layout of the system has been determined and should cover the entire length of the proposed system.
The University will provide a geotechnical report that will include information on groundwater conditions, soil types, terrain, and soil moisture content in the area of the system will be collected. Information on terrain, precipitation rates and irrigation practices will be obtained if not available from records at the installation. Required information will be obtained through boring, test pits, or other suitable exploratory means. The load-bearing qualities of the soil will also be investigated, and the location and nature of potential soil problems will be identified.
Instructions to Professionals
Design Professional shall have a minimum fifteen (15) years firm experience in design of steam energy systems.
Design Professional shall perform all necessary calculations to ensure energy systems will meet Owner’s requirements. Design Professional shall provide these calculations for inclusion in Owner’s project closeout documentation when applicable. Pipe-stress and system-expansion calculations for each expansion compensation elbow using a finite element computer generated three-dimensional analysis. Calculations (including heat loss calculations) shall demonstrate that pipe stresses from temperature changes are within the allowable requirements in ASME B31.1 and the anchors and the guides will withstand the resultant forces. Submitted detailed design layout drawings including the location of all anchors and guides. Layout shall also include all analysis node points. As a minimum, the computer analysis results include node stresses, forces, moments and displacements. Calculations shall be approved, certified, stamped and signed by a registered Professional Engineer in the employ of the underground heat distribution system manufacturer and/or Design Professional.
Condensate return shall be designed with the following preferences in mind:
Gravity return condensate when existing conditions permit
Electric operated condensate pumped return
All systems components of the steam and condensate systems are to be rated to operate at a minimum of 150 PSI and meet all ANSI and ASME Codes and standards.
The campus steam system operates at 60 psi saturated.
Design Professional will include a log of soil conditions along the pipe line right-of-way at pipe depth on the drawings which gives, as a minimum, soil classification, moisture content, soil resistivity and pH, bearing strength and unstable conditions. Design Professional will provide details at building entries on the contract drawings to show pipe elevation, floor and grade elevation, building wall construction and existing equipment. Include location of valve manhole and/or valve boxes, branch run outs, and isolation valves on the contract drawings. Provide details at manhole entries on the contract drawings to show pipe elevations; floor, top, entrance, and grade elevations; manhole wall construction; anchor location and construction; and existing equipment and piping. Utility plans shall reflect plan and profile of all new distribution lines. Plans will accurately/precisely show all portions of system (i.e. valves, expansion couplers/loops, thrust blocks, etc.), schematic plans/drawings will not be acceptable. Plans shall show all known existing utilities and depths of those utilities where crossed. Design Professional shall coordinate with Owner’s Authorized Representative to acquire necessary information.
Direct Bury Steam and Condensate System
Factory fabricated piping system to have metallic carrier pipe, mineral wool insulation, one inch air space, and a metallic outer conduit with fusion bonded epoxy coating.
Provide cathodic protection for all direct buried steam and condensate piping systems per manufactures installation guidelines. Cathodic testing ports shall be located out of access drives/streets. When possible, place testing ports in sidewalks.
Fusion-bonded epoxy, minimum thickness 0.040 inches. Rated by coating manufacturer for continuous service for at least 25 years at temperatures of 110 degrees C 230 degrees F and having a coefficient of expansion similar to that of steel. Coating shall be applied in accordance with the coating manufacturer's instructions. Factory-inspect for holidays and make repairs as necessary.
Anchor plate shall be ASTM A36/A36M steel, welded to carrier pipe and casing, 0.5 inches minimum thickness and shall include passages for air flow and water drainage through the annular air space in the system. Exterior surface of the anchor plate shall be coated with the same coating material as the casing.
Provide expansion loops, elbows, Z-bends, and anchors where required to relieve pipe stress.
Design expansion compensation for a minimum or150 psi working pressure.
End seals/End glands
Shall be installed in accordance manufacture’s guidelines
Each end seal/gland at the point of vault/ building entry shall have minimum two ¾” NPT thread ports. One located at 12 o’clock position (top of pipe) and one located at 6 o’clock position (bottom of pipe). A minimum of one ¾” isolation valve for draining/testing conduit section shall be located on downstream leg of pipe run at the 6 o’clock position. A minimum of one ¾” conduit vent shall be located on upstream leg of pipe run at the 12 o’clock position.
Provide embossed brass or stainless steel tag hung by brass or stainless steel chain at each end of each conduit or insulated piping in the manholes and buildings. The tag shall identify manufacturer's name, date of installation, and manufacturer's project number.
Wall Penetration Sleeves
Sleeves for foundation wall penetrations shall be fabricated of 10 ga or one-eighth inch (1/8”) thick steel, with two inch (2”) wide collars welded in place, and the entire assembly hot-dip galvanized. Sleeve shall be structurally affixed to wall in conformance with Oregon Structurally Specialty Code, latest edition.
Wall Penetration Seals:
High temperature elastomeric link type seals compressed with corrosion- protected bolts and compression plates; Thunderline Link-Seal Model “T”, no substitutions.
Vaults shall be either reinforced cast-in-place or pre-cast concrete in conformance with all applicable state and local code and designed for minimum AASHTO H-20 traffic loading. Vaults shall be utilized at all locations in direct bury system with equipment requiring inspection and routine maintenance.
Vaults shall have all buried portions of structure waterproofed in conformance with Oregon Specialty Structure Code, latest edition.
All vaults shall have drainage to storm sewer. When possible, favor will be given to gravity drain, otherwise vault(s) shall have designated electrical circuit, GFCI plug and sump pump. Vault interior floor shall be sloped to drain/sump pump.
Vault manhole lids shall not exceed 30” diameter. Manhole lids shall be designed for minimum AASHTO H-20 traffic loading. Vault manhole location shall be coordinated such that ladder to vault floor is not obstructed by pipe or equipment. When vault sizing permits, vault shall two manhole opens, spaced kitty-corner from each other. Manhole rim shall have a maximum of 18” between top of vault and manhole rim elevation.
Vault access ladder shall be designed and installed in accordance with Oregon Administrative Rules Oregon Occupational Safety and Health Division, Oregon Administrative Rules for fixed ladders.
All exposed piping must be insulated and comply with state energy code.
Insulation and jacketing shall be resistant to moisture and mold and shall be resistant to damage or deterioration under the service intended. Materials shall meet the smoke and flame spread ratings required by the governing codes and safety requirements.
EXECUTION AND QUALITY CONTROL
Installation, testing and inspection shall be in conformance with all state and local code as well as manufacturer’s recommendations.
Contractor shall have 25 years direct experience with installation of direct bury steam distribution systems.
Perform testing on the entire piping system prior to bedding and backfilling to verify the integrity of the system. All pipe should be pressure tested for a minimum of 24 hours at 1.5% of design.
Bedding and Backfill
All piping shall be full bedded on sand. Place a minimum 4-inch deep layer on the leveled trench bottom for this purpose.
The first 4 inches over the top of the largest pipe shall be sand, and final 12-inch layer shall be soil in any event.
Immediately after all piping is installed in the ditch, make a partial backfill in the middle of each pipe length leaving the joints exposed for inspection prior to the hydrostatic tests.
Place in layers not exceeding 8 inches deep and compact to 95% of standard proctor maximum density at optimum moisture content. Earth backfill shall be free of rocks over 2 inches in diameter and foreign matter.
Interior: All backfill under interior slabs shall be bank sand.
Exterior: Excavated material may be used outside of buildings at the contractor's option.
Tests of Steam Distribution Piping
New steam distribution piping systems which connects to existing hot steam lines shall be tested as follows
The new system shall be installed and the ends of the lines blanked off prior to making the connection to the existing hot line.
The line shall then be hydrostatically tested as specified and thoroughly flushed out.
Make final connections to existing hot lines, energize, and waste condensate.
De-energize and open and clean all dirt legs and strainers. (The purpose of this test is twofold: (1) To stress line under expanded conditions prior to hydro test; and (2) To knock off and then flush out as much mill scale and debris as possible.)
Earthwork shall be in accordance with OSU Construction Standard 31 00 00.
All Work under this section will require a final punch list walk thru at project Substantial Completion. The walk thru shall include Contractor, Owner’s Authorized Representative, Responsible Maintenance Manager and/or Manager’s Designee.