FUSION TANKS LIQUID STORAGE SYSTEMS

MODEL SPECIFICATION -ISOFUSION®

GLASS FUSED BOLTED STORAGE TANKS

1.  GENERAL

1.1  Scope of work

Supply and erect a Glass-Fused-to-Steel bolted sectional tank (s), including foundation, tank cover, tank structure and appurtenances as shown on the Engineer's drawings, and described herein.

All labor, materials, plant, equipment and tools, as required for the construction of the storage tank shall be included.  

1.2 Qualifications of Tank Supplier  

The Bidder shall offer new tank structures as supplies from a Manufacturer specializing in the design, fabrication and erection of factory applied Glass-Fused-to-Steel, bolted sectional tank systems.  The Manufacturer shall own and operate its own production plant, fabricate and glass coat the tank plates at one location so as to provide full quality control responsibility over product.

1.3 Pre-qualification

Pre-approved tank manufacturers:

The Engineer's selection of factory applied Glass-Fused-to-Steel bolted sectional tank construction for this facility has been based upon the design criteria, construction methods specified, and optimum coating for resistance to internal and external tank surface corrosion. Deviations from the specified design, construction or coating details, shall not be permitted.  

Alternative Glass-Fused-to-Steel bolted sectional tank systems, as provided by other Manufacturers, will be considered for prior approved by the Engineer. Manufacturers lacking the experience requirement will be considered if the Manufacturer provides a satisfactory 5 year 100% Performance Bond in lieu of evidence of experience and long term operations for tanks of a similar application.  

Tank suppliers wishing to pre-qualify shall submit the following to the Engineer for consideration:  

a) Typical structure and foundation drawings.  

b) List of tank materials, ancillary equipment and tank coating specifications.  

c) List of five (5) tanks presently in service for a similar duty, of size and character   specified herein, operating satisfactorily for a minimum of five (5) years, including reference name, location, duty and year of supply.  

Only bids from tank suppliers who have successfully pre-qualified will be considered.

1.4   Evaluation  

The Engineer shall fully consider the life time cost implications of the diverse range of tank sheet coatings and finishes available and reserves the right to evaluate all bids based on life time costs (long term operation, tank shut down time, coating and maintenance costs). Values to be used in this evaluation will be at the discretion of the Engineer, as detailed in this specification and bid tabulation form.

As a minimum the Engineer shall consider such cost implications over a 30 year operational period.  

The Engineer will add all such costs, dependent upon the type of tank offered, to the Bidder's bid price to determine the effective low bid for purposes of making the award.  

1.5  Submittal Drawings and Calculation

Construction shall be governed by the Owner's plans and specifications showing general dimensions and construction details, after approval by the Engineer of submittal drawings prepared by the Manufacturer.  

There shall be no deviation from these drawings and specifications, except upon written order or approval from the Engineer.

The Bidder is required to furnish, for the review and approval by Engineer,_____sets of 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. All such submissions shall be stamped by a Registered Professional Engineer licensed in the State of _______________________as well as by an engineer employed on the tank Manufacturer's engineering staff.  

When approved, two sets of such prints and submittal information will be returned to the Bidder marked "APPROVED FOR CONSTRUCTION" and these drawings will then govern the scope of work detailed thereon. The approval by the Engineer of the tank supplier's drawings shall be on approval relating only to their general conformity with the bidding drawings and specifications and shall not guarantee detailed dimensions and quantities, which remains the Bidder's responsibility.

2.      DESIGN CRITERIA 

         Nominal Diameter:                                ___________________    ft/m³

         Sidewall Height:                                    ___________________    ft/m

         Nominal Capacity:                                ___________________    US Gallons/m

         High Water Elevation:                           ___________________    ft/m

         Finished Floor Elevations:                     ___________________    ft/m  

2.2 Design Standards

      Option a) The tank plate/sheet materials, design, fabrication and erection of the sectional tank    shall conform to the AWWA Standard "Factory- Coated Bolted Steel Tanks for Water Storage" ANSI/AWWA D103 - 97.

      Option b) Conformance with AISC Design specification.

      Option c) Manufacturer's In-house Design Standard supported by design calculations.  

         Roof Snow Load:                                 __________________ lb/ft²/kgs/m²  

         Roof Live Load:                                   __________________ b/ft²/kgs/m²  

         Imposed Mechanical Load:                  __________________ lb/ft²/kgs/m²  

         Wind Speed:                                        __________________ mph  

         Shape Factor:                                       __________________  

         Allowable Soil Bearing Capacity:         __________________ lb/ft ²/kgs/m²  

        Internal Pressure:                                  __________________  Ins.WG/                                                                                                            mmWG/           

2.4 Contents Characteristics

       Contents Description:                            __________________

       PH:                                                        __________________ °F/°C

       Temperature:                                        __________________

       Concentration:                                      __________________ ppm

3. MATERIALS            

     3.1  Plates and Sheets

Plates and sheets used in the construction of the tank shell, tank floor and (optional) tank roof, shall comply with the minimum standards of AWWA D103-97, Section 2.4. Such plates shall as a minimum, conform to ASTM requirements and may be sourced from reputable International steel mills.

Test Certificates and Certificates of Conformity shall be available for the Engineers inspection if required. Such Certificates shall be requested at the time of issue of the Purchase Order.  

3.2  Horizontal Wind Stiffeners

Wind stiffener at top of tank shall provide a flat, horizontal, continuous surface at tank rim level, compatible with any roof type that may be included within the scope of works.  

Wind stiffeners shall be steel, hot dipped galvanized-rolled steel angle or web truss types.

 3.3 Bolt Fasteners

Bolt used tank lap joints shall be 1/2" - 13 UNC-2A rolled thread with hot dipped galvanized coating. The bolts shall have a minimum tensile strength of 113800 psi with shear stress calculated at 0.25 of the tensile strength in accordance with AWWA requirements and a minimum permanent set limit of 91000 psi.

All bolts for tank shell and roof (where applicable) shall be installed such that the head portion is located inside the tank and the washer and nut are on the exterior.

All lap joint bolts shall be properly selected such that threaded portions will not be excessively exposed in the "shear plane" between tank sheets. Also, bolt lengths shall be selected to achieve a neat and uniform appearance. The torque values (as set down in the Manufacturer's Builders Guide) shall not be exceeded during tank construction.  

All lap joint bolts shall be designed to prevent rotation during tightening.  

3.4  Bolt Head Encapsulation

All tank shell structure bolts shall have UV resistant polyethylene encapsulation of the bolt head.

The lap joint sealant shall be a one component moisture cured polyurethane compound. The sealant shall be suitable for contact with potable water and meet applicable FDA Title 21 regulations where necessary, as well as, local health department guidelines for such use.

The sealant shall be used to seal lap joints, bolt connections and sheet edges. The sealant shall cure to a rubber-like consistency and have excellent adhesion to the glass coating, have low shrinkage, and be suitable for interior and exterior exposure.

The sealant shall be Sika 1A or suitable, equivalent materials approved by the Engineer.

EPDM or Neoprene gaskets and tape type sealer shall not be used other than for shell manway door/hatch.

Note:  FDA title 21/ NSF registered material shall not be a requirement for non-potable water           applications.  

4.  GLASS COATING  

4.1    Surface Preparation

Sheets shall be steel ½  grit-blasted to a silver gray finish on both sides to the equivalent of SA2 ½ or SSPC-10. Sand blasting and chemical pickling of steel sheets is not acceptable.

The surface anchor pattern shall be not less than 1.0 mil. 

4.2    Cleaning

Immediately after fabrication and grit blasting and prior to application of the coating materials, all sheets shall be thoroughly cleaned by an alkali wash and a hot rinse process providing rust inhibition followed by heat drying.  

4.3   Coating - Double Cost, Single Fire Process

All sheets shall receive one coat of nickel rich pre-coat to both sides followed by heat drying.

A coat of cobalt rich glass slip shall be continuously applied by reciprocating sprays to both sides of the sheet followed by heat drying, After inspection  

sheets shall then be fired through the furnace at minimum 1500° F. Sheets with visual spray or glass defects shall be rejected at this point.  

The resulting melting and bonding of the cobalt rich, silica glass frit formulation to the steel shall form a composite glass surface having general acid/alkali resistance to solutions in the range pH 3 to pH 9.

At all times firing of the coating shall be in strict accordance with the Manufacturer's quality process control procedures, including firing time, furnace humidity and temperature control.

Internal tank sheet color to be Cobalt Blue (Munsell 5 PB 2/4, RAL 5013, BS 4900 20-C-40) unless otherwise stated with external sheet color cobalt Blue or Dark Green (Munsell 2.5GY 2/2, RAL 6006, BS 4900 12-B-29).

Sample tests shall be carried out by the Manufacturer to ensure that the Enamel/Glass shall meet the physical properties and chemical resistance characteristics of the Manufacturer's published specification.  

4.4    Inspection

Inspection procedures shall be carried out within the Manufacturer's plant under ISO 9001 Quality Systems.

Finished sheets shall be inspected for coating thickness using an approved instrument suitable for a measurement range of 0-20.0 mils, The Instrument shall be regularly checked against the Manufacturer's approved calibration standard.

The average thickness of the glass coating shall be maintained in the range from 7.1 mils to 11.0 mils. At no point shall the thickness of the glass coating be less than 7.1 mils. Plates having an average thickness outside of these limits shall be rejected.

Electronic color control shall be used on the external surface to ensure that color uniformity is achieved within the Manufacturer's specified parameters. Sheets of a color outside of these limits shall be rejected.

The external/non-contact surfaces of all sheets shall be inspected visually under good daylight (or equivalent lighting) for defects in the glass coating, any sheet having visible defects larger than 0.04 inch shall be rejected. Any sheet having more than 3 visible lesser defects per square yard of external surface shall be rejected. Any visible defects on the external surface of accepted sheets shall be repaired to the Manufacturer's approved procedure.

An electrical Holiday detection test shall be performed to the contact surface of every sheet in accordance with ISO 8289. The test instrument shall be a 9v detector having 90,000 ohms resistance using 3% sodium nitrite solution as the approved wetting agent.

Sheets having any discontinuities in the glass contact surfaces shall be rejected.  

Only finished sheets with glass continuity defects the contact surface shall  be released for packing.  

An owner representative may be present during these inspection procedures at their own cost.

4.5  Sheet Edges

All sheet edges, bolt holes and pre-formed openings shall have a limited glass cover (Glass-Fused-to-Steel materials perform to their optimum where the glass is in compression - sheet edges are often in tension).  

A further factory applied coating of a quick drying, single component, stabilizing finish, reinforced with flat self leafing glass flake, shall be applied to all sheet edges to provide additional protection during transport and site storage. Further protection shall be provided by the correct use of the approved sealants during construction, application of the sealant and the profile detail of the sealant beading (internal and external) to be strictly in accordance with the Manufacturer's Building Manual.

4.6 Packing

All finished sheets shall be handled within the manufacturing plant using suction pads.

All approved sheets shall be protected from damage prior to packing for shipment.

Heavy paper sheets shall be placed between each panel to eliminate sheet-to- sheet abrasion.

Individual stacks of panels will be wrapped in heavy duty black plastic and steel banded to special wood pallets built to the roll radius of the tank panels where necessary. This procedure eliminates contact movement of finished panels during shipment.  

5.  ERECTION

Field erection of the Glass-Fused-to-Steel, bolted-steel tank shall be in accordance with the procedures outlined in the Manufacturer's Building manual and performed by an Authorized Distributor of the tank Manufacturer, regularly engaged in erection of these tanks or a suitably qualified specialist sub contract builder under the control and supervision of the Authorized Distributor.  

The floor design if required, shall be Glass-Fused-to-Steel. Bolted panels shall be placed over a compacted sand base contained by a concrete ring wall.  

Leveling of the starter ring (or first full ring) shall be required. The maximum differential elevation within the ring shall not exceed 0.11 inch, nor exceed 0.04 inch within any 3ft. length.  

Specialized erection jacks and building equipment shall be used to erect the tanks - low profile, open topped tanks up to 25 ft. high may be built using the stacking method (built from foundations upwards) using suitable plant and equipment.  

Particular care shall be taken in handling and bolting of the tank panels and members to avoid abrasion of the coating system. All surface areas may be visually inspected by the Engineer during construction and prior to liquid tests.  

An electrical Holiday test shall be performed on all contact surfaces of the tank shell plates during erection using a nine (9) volt leak detection device having 90,000 ohms resistance. Any electrical leak points found on the contact surface shall be repaired in accordance with the Manufacturer's published touch up procedure. After completion of tank build, but before tank cleaning and hydraulic testing the Engineer shall sign the Manufacturer's standard Certificate of Satisfaction issued by the Authorized Tank Distributor.

No backfill or mechanical loads shall be placed on the tank sidewall without prior written approval and design review by the tank Manufacturer. Any backfill shall be placed according to the instructions of the Manufacturer.  

6. APPURTENANCES

The ancillary items of equipment shall be installed as shown on the plans and as detailed in these specifications. They may include, but are not restricted to the following items:  

An outside ladder with safety cage beginning a minimum of 8 ft. above the level of the tank bottom and at the location designated. Outside ladder and cage shall meet Occupational Health and Safety Administration (OSHA 29 CF3 part 1910) requirements.  

6.2  Inside Tank Ladder (Optional)  

An inside tank ladder, if required, shall be installed below the roof hatch and shall be fabricated of type 304 or 316 stainless steel and meet Occupational Health and Safety Administration (OSHA 29 CF3 part 1910) requirements.  

Alternatively, internal ladders constructed from Fibre Reinforced Plastic (FRP) may be deemed acceptable.

6.3 Shell Access Manway

One manway having a minimum opening size of 24" shall be provided in the middle of the tank sheet clear of any vertical and horizontal bolt seams. The manway shall include a reinforcing frame and cover plate with a hinged support for cover removal. The manway shall comprise cover plate sealed with an approved gasket system.

6.4 Inlet and Outlet Connections

Inlet, outlet and overflow connections shall conform to the sizes specified on the submittal drawings and shall be located so as to avoid vertical and horizontal bolt seams. Positions shall be agreed between the Engineer and the Authorized Tank Distributor.

Where connections are shown to pass through tank panels, they shall be

a) Field located, saw cut, (acetylene torch cutting, grinding, or welding is not permitted) and shall utilize an interior and exterior flange assembly.

b) Pre-cut by the tank Manufacturer prior to glass application.

Sika IA joint sealant (or similar approved) shall be applied on any cut panel edges or bolt connections.

Inlet, outlet and overflow connections shall be hot-dipped galvanized steel.  

6.5 Cathodic Protection

Cathodic protection may be supplied at the request of the Owner or the Engineer, who should seek the approval of the Tank Manufacturer or his Authorized Distributor regarding the fitting of this equipment to the structure.  

7. FIELD TESTING

 7.1  Leak Test

Following completion of erection, low voltage electrical testing and cleaning of the tank, (and making due allowance for the full curing of the sealants) the structure shall be tested for liquid tightness by filling to its overflow elevation for a 24 hour period.

Any leaks disclosed by this testing shall be corrected by the erector in accordance with the Manufacturer's recommendations.

Water required for testing shall be furnished by the Owner at the time of tank erection completion, and at no charge to the Authorized Tank Distributor.

Disposal of test water shall be the responsibility of the Owner.

Labor and equipment necessary for tank testing shall be included in the price of the tank.

Upon satisfactory completion of the 24 hrs. hydraulic leak test the Engineer shall sign the Manufacturer's Certificate of Satisfaction issued by the Authorized Tank Distributor.  

8.    DISINFECTING  

8.1 Sika 1A

Disinfection shall not take place until polyurethane joint sealant is fully cured (10 to 12 days @ 73 F 50% Relative Humidity).

The tank shall be disinfected by chlorination in accordance with AWWA-C 652 - 92 section 4. Parts 1 and 2.  

8.2 For tanks requiring disinfection but where other sealants are utilized due to severe operating conditions within the tank or the nature of the contents dictates the use of other suitable sealing materials, a full written disinfection method statement shall be issued by the Manufacturer for the approval of the Engineer.  

9. WARRANTY

9.1 One Year Warranty

If within a one year period from the date of delivery to the job site the tank, or any part there of, shall prove to be defective by reason of poor design, materials or manufacture upon examination by the Manufacturer or his Authorized Distributor the Manufacturer will supply an identical or similar replacement part F.O.B. the Manufacturing plant or at it's own option will repair the part.  

9.2 Five Years Warranty

If within a five year period from the date of delivery to the job site the Glass- Fused-to-Steel metal sheet (but no other products or materials) shall prove to be defective by reason of poor design, materials or manufacture upon examination by the Manufacturer or his Authorized Distributor the Manufacturer will supply an identical or similar replacement part F.O.B. the Manufacturing plant or at its own option will repair the part.  

10.  CONSTRUCTOR'S RESPONSIBILITY

The constructor shall erect the structure free of defects in workmanship. This responsibility shall be in effect for a period of 12 months from the date of acceptance but no more than 12 months from the date of completion of installation by the constructor. Any faulty workmanship found within those periods shall be repaired by the constructor.  

11.   INSPECTION

On or near the one year anniversary date of tank installation (but not more than 14 months from date of delivery of tank materials to job site) the Manufacturer's Authorized Distributor shall make a visual inspection of the tank interior coating and appurtenances, tank exterior coating and appurtenances, and the immediate area surrounding the tank.

The Manufacturers Standard Inspection Report Form shall be completed and be filed with the Owner and the Authorized Tank Distributor at this time.