Premium Epoxy Powder-Coated, Bolted Steel Water Tank

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POTABLE WATER SPECIFICATION

PREMIER EPOXY POWDER-COATED, BOLTED STEEL WATER TANK

PART 1 - GENERAL

1.01 Scope of Work

A. Furnish and erect epoxy coated, flat panel bolted-steel potable water storage tank, including tank structure, tank foundation, and tank appurtenances as shown on the contract drawings and described herein.

B. All required labor, materials and equipment shall be included.

1.02 Qualifications of Tank Supplier

A. Tank supplier shall have minimum five years experience in similar type projects.

B. Manufacturer shall be specialized in the design, fabrication and erection of factory applied epoxy powder coated, bolt together tank systems. The manufacturer shall fabricate and coat the tank in the same facility which it owns and operates.

C. Tank supplier shall supply erectors with minimum five years experience in the fabrication of the supplied tank. The tank erectors must be employed by the tank supplier. Subcontract erectors will not be allowed.

D. The supplier shall be fully responsible for the entire installation including tank erection, and the ultimate water tightness of the complete installation.

E. Strict adherence to the standards of design, fabrication, erection, product, quality, and long-term performance, established in this Specification will be required by the Owner and Engineer.

F. Tank supplier shall be the Tank Connection, LLC or approved equal.

1.03 Submittal Drawings and Specifications

A. Construction shall be governed by the Owner’s drawings and specifications showing general dimensions and construction details, after written approval by the Engineer of detailed erection drawings prepared by the tank bidder. There shall be no deviation from the drawings and specifications, except upon written order from the Engineer.

B. The bidder is required to furnish, for the approval of the Engineer and at no increase in contract price, six (6) sets of complete specifications and construction drawings for all work not shown in complete detail on the bidding drawings. A complete set of structural calculations shall be provided for the tank structure and foundation. A Professional Engineer licensed in the specified state shall stamp all calculations and drawings.

C. The approval by the Engineer of the tank supplier’s drawings shall be an approval relating only to their general conformity with the bidding drawings and specifications and shall not guarantee detail dimensions and quantities, which remains the bidder’s responsibility.

1.04 Tank Design Standards

A. The materials, design, fabrication and erection of the bolt together tank shall conform to the AWWA Standard for “Factory-Coated Bolted Steel Tanks for Water Storage” – ANSI/AWWA D103-1997.

B. American Petroleum Institute (API) 12B tanks shall not be acceptable.

C. The tank shall be designed to meet the most current wind and seismic design standards for the tank’s proposed location.

1.05 Coating Standards

A. The tank coating system shall conform solely to Section 10.6 Thermoset Powder Coatings of ANSI/AWWA D103-1997.

B. All materials furnished by the tank manufacturer, which are in contact with stored water, shall be certified to meet ANSI/NSF Standard No. 61. Certification of a coating type alone will not be sufficient to meet this requirement. Certification of a distributor, and not the tank or coating manufacturer, will not be accepted.

PART 2 - PRODUCTS

2.01 Tank Criteria

A. Tank Size: Diameter and Height (Feet)

B. Tank Capacity: Working Capacity and Nominal Capacity – US Gallons. The tank supplier shall recommend the actual freeboard required based on the supplier’s seismic calculations.

C. Job Site Location

D. Liquid stored

E. Specific Gravity

F. pH of Liquid

G. Temperature

H. Design Pressure

I. Deck Live Load

J. Wind Speed

K. Seismic Zone

2.02 Plates and Sheets

A. Plates and sheets used in the construction of the tank shell, tank floor and tank roof, shall comply with the minimum standards of AWWA D103-1997.

B. Design requirements for mild strength steel shall be ASTM A36 or ASTM A1011 Grade 30, 36, 40, or 50 with a maximum allowable tensile stress 18,000 psi.

C. Design requirements for high strength shall be ASTM A1011 Grade 42, 50, 55, or 60 with a maximum allowable tensile stress of 30,000 psi, unless otherwise noted in the engineering specifications and/or submittals.

2.03 Rolled Structural Shapes

A. Material shall confirm to minimum standards of ASTM A36 or AIS

1010.

2.04 Horizontal Wind Stiffeners

A. Web truss stiffeners shall be of steel.

B. Rolled steel angle stiffeners are not permitted for intermediate

stiffeners.

2.05 Bolt Fasteners

A. Bolts used in tank lap joints shall be ½ - 13 UNC-2A rolled thread, and shall meet the minimum requirements of AWWA D103, Section 2.2.

B. Bolt Material

1. SAE Grade 5 (1” thru 1 1/2 “)

a. Tensile Strength – 105,000 psi Min.

b. Proof Load – 74,000 psi Min.

2. SAE Grade 8 (1” thru 1 1/2'”)

a. Tensile Strength – 150,000 psi Min.

b. Proof Load – 120,000 psi Min.

C. Bolt Finish – Galvanized.

1. 2.0 Mills Minimum – under bolt head, on shank and threads.

D. Bolt Head Encapsulation

1. High impact polypropylene copolymer encapsulation of entire bolt head up to the splines on the shank.

2. Resin shall be stabilized with an ultraviolet light resistant material such that the color shall appear black. The bolt head encapsulation shall be certified to meet the NSI/NSF Standard 61 for indirect additives.

E. All bolts on the vertical tank wall shall be installed such that the head portion is located inside the tank, and the washer and nut are on the exterior.

F. Bolt lengths shall be sized to achieve a neat and uniform appearance. Excessive threads extending beyond the nut after torquing will not be permitted.

2.06 Sealants

A. The lap joint sealant shall be a one component, moisture cured, polyurethane compound. The sealant shall be suitable for contact with potable water and shall be certified to meet ANSI/NSF Additives Standard 61 for indirect additives.

B. The sealant shall be used to seal lap joints and bolt connections and edge fillets for sheet notches and starter sheets. The sealant shall cure to a rubber-like consistency, have excellent adhesion to the epoxy coating, low shrinkage, and be suitable for interior and exterior use.

C. Sealant curing rate at 73^oF and 50% RH

D. Tack-free time: 6 to 8 hours

E. Final cure time: 10 to 12 days

F. Neoprene gaskets and tape type sealer shall not be used in liquid contacting surfaces.

2.07 Epoxy Coating Specification

A. Surface Preparation

1. Following the shearing process, sheets shall be steel grit blasted on both sides to the equivalent of SSPC-SP10. Sand blasting and chemical pickling of steel sheets is not acceptable.

2. All sheets shall be powder coated immediately after steel grit blasting.

B. Cleaning

1. After fabrication and prior to application coating system, all sheets shall be thoroughly cleaned by a caustic wash and a hot rinse process followed immediately by drying.

2. Inspection of the sheets shall be made for traces of foreign matter or rust. Any such sheets shall be recleaned or grit blasted to an acceptable level of quality.

2.08 COATING

A. No shaping, bending, punching, flanging, or grinding may be done on the steel after blasting and before coating. Field coating, except for touch-up will not be permitted.

B. Coatings shall be in accordance with AWWA D103, Section 10.6 and interior coatings shall be NSF standard 61 approved.

C. Interior coating shall be LIQ Fusion 7000 FBE™ by Tank Connection or approved equal. Interior coating shall be thermally cured, baked-on powder epoxy applied at 7 mils average DFT.

D. Exterior coating system shall be as follows:

1. Primer: LIQ Fusion 7000 FBE™, thermally cured baked-on powder epoxy applied at 3 mils average DFT.

2. Topcoat: One coat of “UV” protective polyurethane

applied to 2.0 mils nominal DFT. An exterior polyester

powder topcoat will not be allowed.

E. The same epoxy coating as applied to the sheet surface shall be applied to exposed edges.

F. The color selected for the exterior coating shall be approved by the Engineer prior to commencement of coating.

2.09 Factory Inspection

A. Coated sheets shall be inspected for mil thickness (Mikrotest or equal).

B. An electrical leak detection test shall be performed on the inside surface after fabrication of the sheet. Sheets with more than five electrical leaks or holidays shall be rejected so as to minimize field touch up.

2.10 Packaging

A. All sheets that pass Factory Inspection and Quality Control checks shall be protected from damage prior to packaging for shipment.

B. Heavy paper or plastic foam sheets shall be placed between each panel to eliminate sheet-to-sheet abrasion during shipment.

C. Individual stacks of panels will be banded or bolted to special wood pallets built to roll-radius of the tank panels. This procedure eliminates contact or movement of finished panels during shipment.

D. Shipment from the factory will be by truck, hauling the tank components exclusively.

PART 3 - EXECUTION

3.01 Foundation

A. The tank foundation design is a part of this contract and shall be completed by tank supplier.

B. The tank foundation shall be designed by the tank supplier to safely sustain the structure and its live loads.

C. Tank footing design shall be based on the soil bearing capacity as determined by geotechnical analysis performed by a licensed soils engineer provided by the owner.

3.02 Tank Floor

A. Epoxy coated steel floor

1. The floor is to be an epoxy-coated bolted steel floor. Bolted steel panels shall be placed over a base, such as compacted gravel, filler cushion and foundation. The base, filler cushion and foundation shall be designed by the tank supplier and approved by the Engineer prior to construction. Examples of acceptable filler cushions include sand or non-extruding and resilient bituminous type meeting the requirements of ASTM D1751. The filler shall be placed between the tank floor and the gravel base to act as a cushion. Examples of acceptable foundations in order of preference include: foundation grade band with compacted fill, concrete ringwall with compacted fill, or concrete slab.

2. If a concrete foundation is used by the tank supplier, the concrete design shall meet ACI 318 and the quality of concrete work shall meet ACI 301.

3. A plastic encapsulated nut shall be used to cover the bolt threads exposed on the inside of the floor. The plastic encapsulation shall be Noryl GFN2-701S.

3.03 Sidewall Structure

A. Field erection of the epoxy coated, bolted steel tank shall be in strict accordance with the procedures outlined by the manufacturer, using Tank Connection, LLC or approved equal.

B. Particular care shall be taken in handling and bolting of the tank panels and members to avoid abrasion of the coating system. Prior to a liquid test, the Engineer may visually inspect all surface areas.

C. An electrical leak test shall be performed after the tank erection is complete using a wet sponge low voltage leak detection device. All electrical leak points found on the inside surface shall be repaired in accordance with manufacturer’s published touch up procedure’s.

D. The placement of sealant on each panel may be inspected prior to placement of adjacent panels. However, the Engineer’s inspection shall not relieve the bidder from his responsibility for liquid tightness.

E. No backfill shall be placed against the tank sidewall without prior written approval and design review of the tank manufacturer. Any backfill shall be placed according to the strict instructions of the tank manufacturer.

3.04 Roof

A. Steel deck

1. Tank shall include a radially sectioned roof fabricated from epoxy-coated, bolted steel panels, as produced by the tank manufacturer, and shall be assembled in a similar manner as the sidewall panels. The roof shall be clear-span and self supporting or center supported. Both live and dead loads shall be carried by the tank walls and any center supports. The manufacturer shall furnish one roof opening which shall be placed near the outside tank ladder and which shall be provided with a hinged cover and a hasp for locking. The square opening shall have a clear dimension of at least twenty-four (24”) inches in both directions. The opening shall have a curb at least four (4”) inches in height, and the cover shall have a downward overlap of at least two (2”) inches, or a gasketed weather-tight cover in lieu of the four (4”) inch curb and two (2”) inch overlap.

B. Roof Vent

1. A properly sized vent assembly in accordance with AWWA D103 shall be furnished and installed above the maximum water level of sufficient capacity so that at maximum design rate of water fill or withdrawal, the resulting interior pressure or vacuum will not exceed 0.5” water column.

2. The vent shall be designed so that an outlet pipeline break that causes rapid emptying of the tank shall not cause the tank roof or walls to collapse.

3. The overflow pipe shall not be considered to be a tank vent.

4. 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 or stainless steel shall be provided and designed to open should the screen become plugged by frost or debris.

3.05 Appurtenances

A. Pipe Connections

1. Where pipe connections are shown to pass through tank panels, they shall be either factory placed or field located, saw, cut, (acetylene torch cutting or welding is not permitted), and utilize an interior and exterior flange assembly. The tank shell reinforcing shall comply with AWWA D103. The Manus 75 mastic sealant shall be applied on any cut panel edges or bolt connections.

2. Overflow piping shall be a specified inside diameter (inches) schedule 10 or 40 carbon steel (dependent upon diameter), and coated externally with epoxy.

B. Exterior Tank Ladder and Perimeter Guardrail

1. An outside tank ladder shall be furnished and installed with the design meeting or exceeding OSHA requirements.

2. Safety cage and step-off platforms shall be fabricated of galvanized steel. The outside tank ladder shall be equipped with a hinged lockable entry device as shown on the plans.

3. A partial perimeter guardrail shall be fabricated of galvanized steel. The guardrail shall extend 5’ either side of the tank ladder and shall meet or exceed OSHA requirements.

C. Sidewall Access Door

1. One bottom access door shall be provided as shown on the contract drawings.

2. The manhole openings shall be a minimum of 24 inches in diameter. The access doors and the tank shell reinforcing shall comply with AWWA D103, Sec. 5.1. The center of the manhole shall be 42 inches above the bottom of the tank.

D. Flanges

An overflow with weir box shall be furnished and sized to exceed inlet capacity.

E. Identification Plate: A manufacturer’s nameplate shall list the tank serial number, tank diameter and height, and maximum design capacity. The nameplate shall be affixed to the tank exterior sidewall at a location approximately five (5) feet from grade elevation.

3.06 Installation

A. Installation shall be completed using the ground jacking system insuring safer working conditions. The tank shall be erected starting from the top of the tank working toward the bottom of the tank.

3.07 Hydrostatic Testing

A. Following completion of erection and cleaning of the tank, the

structure shall be tested for liquid tightness by filling tank to its

overflow elevation.

B. The contractor in accordance with the manufacturer’s

recommendations, shall correct any leaks disclosed by this test.

C. The owner shall furnish water required for testing at the time of tank

erection completion, and at no charge to the tank erector. Disposal

of test water shall be the responsibility of the owner.

3.08 Disinfection

A. Standards

1. The tank structure shall be disinfected at the time of testing by chlorination in accordance with AWWA Standard C652 “Disinfections of Water Storage Facilities”. Disinfection shall be completed by a competent water treatment contractor.

2. Disinfection shall not take place until tank sealant is fully cured (see Sect.3.5.3).

3. Acceptable forms of chlorine for disinfection shall be:

a. Liquid chlorine as specified in AWWA C652.

b. Sodium hypochlorite as specified in AWWA C652.

c. Calcium hypochlorite (HTH) is not acceptable.

4. Acceptable methods of chlorination per AWWA C652:

a. Section 4.1.1.

b. Section 4.1.2 – chemical feed pump only (4.1.2.1.)

c. Section 4.3

d. Section 4.2 is not acceptable.

3.09 Tank Manufacturer’s Warranty

A. The tank manufacturer shall include a warranty for the tank materials and coating. As a minimum, this warranty shall provide assurance against defects in material, coatings and workmanship for a period of five years.

END OF SECTION