SECTION WELDED STEEL WATER STORAGE TANKS

Transcription

1 SECTION WELDED STEEL WATER STORAGE TANKS PART 1 GENERAL 1.01 SUMMARY A. Section Includes: 1. Elevated tanks. 2. Appurtenances and accessories. B. Related Sections: 1. Section Concrete Foundation for Storage Tanks 2. Section Concrete Floor Slab on Grade 3. Section Coating Systems for Water Storage Tanks 4. Section Disinfection of Water Storage Facilities 5. Section Riser Insulation for Water Storage Tanks 1.02 REFERENCES A. ANSI/AWWA 1. D100 - AWWA Standard for Welded Steel Tanks for Water Storage 1.03 DESCRIPTION A. General Requirements: 1. Tank Style: Single Pedestal Hydrospheroid. 2. Nominal Capacity: 400,000 gallons. 3. Head Range: Verify with Tank Manufacturer. B. Design Requirements: 1. Include an allowance of 40 pounds per square foot on the horizontal projection for the pressure resulting from the snow load. 2. Include allowances for pressures resulting from a 100-mph wind load on all surfaces in accordance with AWWA D100, Section Include allowances of 125 psf for the load resulting from the construction of a second floor in the column interior. 4. No corrosion allowance is required. 5. No seismic design is required. 6. Design Metal Temperature: minus 15 degrees Fahrenheit SUBMITTALS A. Shop Drawings: 1. Provide elevation and sectional view Drawings of the column, tank, and all appurtenant equipment and accessories. 2. Indicate locations, dimensions, material specifications, and finish requirements. 3. Drawings shall be sealed by a Professional Engineer licensed in the State of Minnesota. B. Construction Procedures: 1. Provide design, detail Drawings, and procedures as follows: a. Tank: Shop and field weld procedures for all structural joints. C. Design Data: 1. Provide a head range/capacity table showing capacity of the tank in gallons at all levels in 1-foot increments. 2. Provide a summary of the design for the foundation, column, tank, and other components, describing the design basis, loads, load combinations, and results. GAYLO

2 D. Product Data: Provide manufacturer s descriptive information for appurtenant equipment and accessories that are not detailed on the Construction Drawings. E. Reports/Certification: 1. Provide documentation of all tests, inspections, and certifications required by this Section. 2. Submit copies of welder s certification to Engineer prior to any welds being made. 3. Upon Project completion, submit a written report certifying that the tank was inspected as required and providing the information required under AWWA D100, Section F. Operation/Maintenance: Provide operating instructions and maintenance procedures for the tank and applicable appurtenant equipment, mechanical components, and accessories QUALITY ASSURANCE A. Radiographs: After acceptance of the tank structure, the radiographic film shall become the property of the Owner DELIVERY, STORAGE, AND HANDLING A. Handling and Shipping: 1. Handle materials and fabricated components in a manner that will protect them from damage. 2. Allow adequate cure time prior to stacking or shipping coated items. B. Storage and Protection: 1. Protect delivered materials and equipment from damage. 2. Store items in well-drained areas and provide blocking to minimize contact with the ground SITE CONDITIONS A. Location: 1. See Drawings. 2. Access to the Site available via Industrial Avenue. B. Services: 1. Electric Power: a. Electric power is not available at the Site. 2. Water: a. Water is not currently available at the Site. b. Contact the City for rates and procedures GUARANTEE A. Guarantee the footing, tank structure, appurtenant equipment, and accessories against defective design, workmanship, and materials for a period of 1 year from the date of final completion. B. Replace or repair any defective materials or workmanship discovered within the guarantee period at no cost to Owner. PART 2 PRODUCTS 2.01 MATERIALS A. General: 1. All materials provided shall be new, previously unused, in first class condition in compliance with AWWA D100, Section GAYLO

3 B. Fluid Conductors: 1. The inlet/outlet water main and that section of vertical riser pipe below the floor shall be Class 56 Cement Lined Ductile Iron Pipe with mechanical joints in accordance with ANSI A21.51, A21.4, and A All other internal and external piping shall be steel conforming to ASTM A Joints shall be screwed, welded or flanged COMPONENTS A. Water Transmission: 1. Silt Stop: a. Provide a minimum 6-inch high removable silt stop at the riser connection that is flush with the bowl floor. 2. Riser Pipe: a. Support pipe by means of suitable galvanized steel brackets, guides, and hangars. b. Mount support devices on tower wall at minimum 20-foot intervals. 3. Expansion Joint: Install in the vertical section of the riser just above the interior floor. 4. Riser Assembly: a. Install the following items on the riser pipe: 1) Telemetry connection: 1/2-inch coupling with stainless steel nipple and isolation gate valve. 2) Valve: 12-inch. 3) Hose connection: 2-1/2-inch fire hose. 4) Pressure gage: as shown in Drawings. 5) Recirculation pump inlet/outlet piping & valves b. Install items in locations readily accessible from the floor. B. Safety and Access: 1. Roof Handrail: Provide handrail to enclose accessories located on roof. 2. Manholes and Hatches: a. Include watertight covers on each opening. b. Tank floor opening: 1) Operable from ladder located on upper platform and designed to withstand the pressure of the tank contents without leakage. 2) Include steel handwheel operator and threaded components. c. Roof openings: 1) Minimum 4-inch curbs on hatches. 2) Provide aluminum covers with 2-inch down-turned edges, stainless steel hardware, hold-open arm, handle, and hasp. d. Access tube hatch: 1) Locate at top of access tube. 2) Provide chain, hook, and inside handle. 3) Provide a 6-inch vent with removable No. 4 stainless steel screen on hatch cover for access tube ventilation. e. Flanged exhaust hatch: 1) Provided in roof adjacent to access tube. 2) Constructed to allow exhaust fan to be bolted to the hatch for ventilation during painting. 3) The pressure-vacuum vent may be mounted on the exhaust hatch. f. Painter rail hatch: 1) Provided in roof and located to provide access to the interior painters rail near the shell. 2) Provide handle and hasp. g. Painters manhole/vent: 1) Locate near top of support wall and accessible from walkway. 2) Provide access to the exterior painters rail and ventilation for the column. 3. Access Tube: Install tube centrally through the tank to provide access to the roof from the upper platform. 4. Grab Bar: Install in the roof adjacent to access tube hatch. 5. Ladders: a. Material: 1) Tower ladders: Painted steel 2) Access tube ladders: Painted steel GAYLO

4 b. Provide ladders in accordance with current U S Department of Labor, Occupational Safety and Health Administration (OSHA) regulations. c. Secure ladders to adjacent structures by brackets at maximum 10-foot intervals. d. Terminate ladders minimum 48 inches above platforms and landings. 6. Platforms and Landings: a. Minimum width: 4 feet b. Walking surface: Grating c. Provide handrails, mid-rails, and toe plates in accordance with OSHA regulations. 7. Ventilation: a. Tank vent: 1) Material: stainless steel or aluminum components including support frame, screened area, and cap. 2) Fasten support to flanged opening in tank roof. 3) Provide cap to prevent entrance of wind-driven debris or precipitation. 4) Provide minimum 4-inch distance between roof surface and vent cap. 5) Install corrosion resistant No. 4 screen. 6) Maximum fill rate: 1,500 gpm. 7) Maximum discharge rate: 5,000 gpm. 8) Provide self-correcting mechanism for failsafe operation in the event of screen plugging. b. Tower vent: 1) Include removable insect screen. 2) Install minimum of one vent near top of column. 3) Accessible from interior platform. 8. Painters and Inspection Rails: a. Provide permanently installed painter rails attached to the underside of the roof suitable for rolling trolleys. b. Provide exterior mounted painter rails near the top of the tower and accessible via the painters manhole/vent. c. Provide an interior inspection rail located near the top of the tower interior and accessible from the walkway. 9. Ladder Safety Devices: a. SAF-T-CLIMB Fall Prevention System as manufactured by North Specialty Products or equivalent. b. Required components: 1) SAF-T-NOTCH Carrier Rail, Standard Galvanized, ) SAF-T-CLIMB Ladder Rung Clamps, Standard Galvanized ) SAF-T-LOK Sleeve, Provide 3 each. 4) SAF-T-BELT, Provide 3 each. c. Provide on the following ladders: 1) Ladders from grade to walkway. 2) Ladder inside the access tube from the walkway to the roof. C. Drains: 1. Overflow Pipe: a. Install weir box with vortex prevention at the overflow elevation. b. Support pipe by means of suitable brackets, guides and hangars. c. Mount supporting devices at maximum 20 intervals. d. Slope horizontal runs to drain. e. Install No. 4 stainless steel screen at discharge point. 2. Tank Drain: a. Provide 3-inch drain from the low point of the tank floor and connect to the overflow pipe. b. Construct as shown on Drawing detail. 3. Condensate Drain: a. Install drain line from the condensate platform to the overflow pipe. b. Slope to drain ACCESSORIES A. Antenna Conduit: Provide 4-inch conduit adjacent to access tube hatch as shown on Drawings GAYLO

5 B. Coax Support Hanger: 1. Provide coax support hangers in access tube as detailed on Drawings. 2. Coax support hanger by Fulton Technologies or equivalent. C. Caulk: Sikaflex-1a, as manufactured by Sika Corporation, Lyndhurst, NJ, or approved equal SOURCE QUALITY CONTROL A. Mill Inspection: 1. Mill inspection by a commercial agency is required. 2. Provide copies of the mill test report B. Shop Inspection: 1. Shop inspection by a commercial agency is required. 2. Provide inspection reports for stress carrying joint welds in accordance with AWWA D100. PART 3 EXECUTION 3.01 EXAMINATION A. Environmental Conditions: Prior to performing any work, verify the expected temperature, humidity, wind, and weather conditions are within the specified limitations for executing the work. B. Tank Components: After completion of each major component and prior to proceeding with the next stage of construction, verify that tolerance inspections and material quality control tests conform to the requirements of Article STEEL TANK A. Welding: 1. Comply with AWWA D100, Section 8 - Welding for procedures and requirements. 2. Grinding of weld contour shall approximate Condition D of NACE Standard RPO Provide complete penetration on double welded butt joints subject to secondary stress for base materials greater than 3/8-inch thick. 4. Seal weld all water compartment joints. B. Fabrication: Comply with AWWA D100, Section 9 - Shop Fabrication for layout, cutting, forming, edge preparation and workmanship of components. C. Erection: 1. Comply with AWWA D100, Section 10 - Erection for procedures and general requirements. 2. Handrail Installation a. Preassemble handrail on ground. b. Install handrail on tank roof as a complete unit. D. Tolerances: 1. Tank Tolerances: API 650, Section Steel Cone: a. Measure actual imperfections after welding. b. Deviation from theoretical conical surface: Maximum 0.032/RT, when measured in the radial direction over length 4/RT, where R is the radius normal to the plate surface at the point of consideration, and T is the plate thickness FIELD QUALITY CONTROL A. Testing and Inspection: 1. Inspection Procedures: AWWA D100, Section 11 - Inspection. GAYLO

6 2. Provide field measurements of steel cone erection tolerance in the radial direction at 30-degree intervals. 3. Tank Shell Joints: a. Inspect all complete joint penetration welded shell butt joints by the radiographic method. b. Inspect primary stress joints that cannot be radiographed by air carbon arc gouging. c. Prepare and submit a form identifying the following: 1) The specific joint. 2) Justification for the inspection. 3) Recorded length. 4) Findings. END OF SECTION GAYLO