- 2) The sealant shall be used to seal lap joints, bolt connections, and sheet edges. The sealant shall cure to a rubber like consistency, have excellent adhesion to the Fusion Bond coating, have low shrinkage, and be suitable for interior and exterior exposure.
- 3) Sealant curing rate at 73 degrees F and 50% RH.
- (a) Tack-free time: 6 to 8 hours.
- (b) Final cure time: 10- 12 days.
- 4) Neoprene gaskets and tape type sealer shall not be used in liquid contacting surfaces.
2.3 Fusion Bond Powder Coat Specification
- A) Cleaning
- 1) Following the fabrication process, sheets and tank components shall be thoroughly washed and rinsed.
- 2) Washing shall be with a 3-4% solution of DuBois MC-726 and 140°F water.
- 3) The PH level shall be monitored and maintained at 10 to 12.
- 4) Rinsing shall be in a two stage booth and ambient temperature fresh water in the second stage.
- 5) All water shall be removed from sheets and tank components with forced air at ambient temperature.
- B) Surface Preparation
- 1) Sheets and tank components shall be blasted using steel shot S-230.
- 2) Sheets and tank components shall be blasted on both sides providing a surface profile of SSPC-SP10. Anchor profile shall be 1.0 mil minimum.
- C) Powder Coating System
- 1) After cleaning and blasting, the sheets and tank components shall receive a Fusion Bond powder coating on both sides of steel. The powder coating shall be applied with an electrostatic process. The thermoset powder coat system shall be as specified:
||LIQ Fusion 7000 FBE™
||EXT Fusion 5000 FBE™
||EXT Fusion SDP™
*DFT - Nominal dry film thickness
- 3) Interior lining, LIQ Fusion 7000 FBE™ will be applied at 7 mils nominal DFT, with a min/max range from 6-9 mils.
- 4) Exterior prime coat, EXT Fusion 5000 FBE™ will be applied at 3 mils nominal DFT, with a min/max range from 3-5 mils.
- 5) Coating thickness shall be maintained by the use of PLC controlled automatic spray guns preset for the application.
- 4) Roof sheets and hopper or bottom sheets as well as other tank components shall be packaged to prevent damage and then wrapped and banded.
2.4 Support Pedestal/Column - Concrete or steel pedestal design
- A) The support column for the water storage tanks shall be of jump-form concrete construction in accordance with ACI standards 313-91 and ACI 371R-98.
- B) Concrete:
- 1) Compressive Strength:
- (a) Concrete support structure = 4,000 psi (28Mpa)
- (b) Foundations = 3,500 psi (24Mpa)
- 2) Air Entrainment:
- 3) Curing:
- (a) Conform to ACI 318 and ACI 308
- (b) Curing compounds shall be membrane forming or combination curing/surface hardening types conforming to ASTM C309.
- 4) Formwork
- (a) Formwork design, installation and removal shall conform to the requirements of ACI 318 and the recommendations of ACI 347 R.
- 5) Concrete Finish
- (a) Per Section 3.5 of ACI 371R-98
- (b) A beveled-edge rectangular pattern (the size of the 4' tall jump forms) shall be formed into the outer column surface.
- C) A steel pedestal design utilizing RTP construction with Fusion Bond coating system can be proposed as an alternate pedestal design.
- D) An opening shall be made at the base of the column for a 3' x 7' personnel door.
- E) An opening shall be made near the top of the column for 3' x 7' personnel door.
- F) An opening shall be made at the base of the column for a 12' x 12' roll-up access door.
- G) A 6" thick reinforced concrete floor poured over a 3" compacted layer of crushed #57 or 2A stone shall be installed inside at the base of the column.
- A) Roofs shall be constructed of non-corrugated triangular aluminum panels which are sealed and firmly clamped in an interlocking manner to a fully triangulated aluminum space truss system of wide flange extrusions, this forming a spherical dome structure.
- 1) The dome shall be clear-span and designed to be self-supporting from the periphery structure with primary horizontal thrust contained by an integral tension ring. The dome dead weight shall not exceed 3 pounds per square foot of surface area.
- 2) The dome and tank shall be designed to act as an integral unit. The tank shall be designed to support an aluminum dome roof including all specified live loads.
- 3) Materials:
- (a) Triangulated space truss: 6061-T6 aluminum struts and gussets.
- (b) Triangular closure panels: .050"t 3003-H16 aluminum sheet.
- (c) Tension ring: 6061- T6 aluminum.
- (d) Fasteners: 7075 - T73 anodized aluminum or series 300 stainless steel.
- (e) Sealant and gaskets: silicone rubber.
- (f) Dormers, doors, vents and hatches: 6061 - T6, 5086-H34 or 3003-H16 aluminum.
- 4) Roof Vent
- (a) A properly sized vent assembly in accordance with AWWA D103 shall be furnished and installed the maximum water level of sufficient capacity so that at maximum possible rate of water fill or withdrawal, the resulting interior pressure or vacuum will not exceed 0.5" water column.
- (b) The overflow pipe shall not be considered to be a tank vent.
- (c) The vent shall be constructed of aluminum.
- (d) The vent shall be so designed in construction as to prevent the entrance of birds and /or animals by including an expanded aluminum screen (1/2 inch) opening. An insect screen of 23 to 25, mesh polyester monofilament shall be provided and designed to open should the screen become plugged by ice formation.
2.6 Appurtenances (Per AWWA D103, Section 5)
- A) Pipe Connections
- 1) Where pipe connections are shown to pass through tank panels, they shall be field located saw cut, and utilize an interior and exterior flange assembly.
- 2) Overflow piping shall be 8 inch diameter ASTM A312, TP 304L; Schedule 40 stainless steel pipe and ANSI B36.19. The piping shall be installed on the exterior of the tank (as close to the tank as possible), pass thru the walkway, pass into and down the inside of the column, and exit the column near the base emptying onto a stone rip-rap trench.