Special Provision No. 999S19 March Pancake Bridge Deck Anodes, Junction Box Entry and Acceptance Testing of Cathodic Protection System

Transcription

1 ANODES, PANCAKE TYPE - Item No. Special Provision No. 999S19 March 1994 Pancake Bridge Deck Anodes, Junction Box Entry and Acceptance Testing of Cathodic Protection System 1. Scope This special provision specifies the requirements for supply and installation of pancake bridge deck anodes including junction box entry and final acceptance testing of the entire cathodic protection system. 2. Materials 2.1 Anodes Anodes shall be DURCO Pancake Bridge Deck Anodes Type 1. The anode lead cable shall be #10 AWG RWU90, colour black. The lead cable shall be fitted in a hole in the anode with lead alloy caulking (14% antimony, trace of tellurium and balance of lead). The hole shall be sealed with Ozite "B" sealant and plugged with epoxy. The lead cable and connection shall be installed by the supplier in conformance with the manufacturer's specifications. Anodes shall be supplied with sufficient cable to extend from the point of embedment, to the appropriate junction box, without splicing. The resistance between the end of the lead cable and the end of the anode shall not exceed 1 ohm. Anodes shall be supplied by: 2.2 Epoxy Resin Inter Provincial Corrosion Control Ltd. 930 Sheldon Court Burlington, Ontario L7L 5K6 Telephone: Corrosion Service Company Ltd. 369 Rimrock Road Downsview, Ontario M3J 3G2 Telephone: Epoxy resin shall be the same material as supplied from the designated sources for Epoxy Resin Systems. 2.3 Epoxy Paste Epoxy paste shall consist of non-conductive fibres or fine mineral filler added to epoxy resin and curing agent to give a paste-like consistency. As an alternative, Q-Stick 111 may be used without a thickening material. Q-Stick 111 is manufactured by: March 1994 Pg. 1 of 6 SSP999S19

2 Chemque Canada Ltd. 22 Melamie Dr. Brampton, Ontario Telephone: L6T 4K9 2.4 Non-shrink Grout Non-shrink grout shall be Masterflow 713 Grout or Master Builders Set Non-Shrink Grout as supplied by: 2.5 Concrete The Master Builders Co. Ltd 3637 Weston Rd. Toronto, Ontario M9I 1W1 Telephone: Concrete shall be 30 MPa class conforming to OPSS Nominal maximum size of aggregate shall be 9.5 mm. 2.6 Conduit Conduit and accessories shall be rigid PVC type and shall conform to CSA Standard C22.2 No Flexible liquid tight conduit and fittings shall meet the requirements of CSA Standard C22.2 No Equipment 3.1 Multimeter The multimeter shall have an input impedance of not less than 10 megohms when operated at a full scale of 100 mv. The meter shall have an accuracy of 2.5% of the reading in DC volts with a resolution of 100 microvolts. 3.2 AC Resistance Meter The AC resistance meter shall be capable of measuring from 0.1 ohms to 10,000 ohms and shall be insensitive to AC and DC ground currents. The resistance meter shall be calibrated using a 1.0 ohm resistor. 3.3 Holiday Detector The holiday detector shall be capable of producing pulse type output voltages ranging from 500 to 3000 volts. The device shall be equipped with a 1 m wide steel brush to scan the concrete surface and shall produce a loud audible signal when metals that are electrically connected to the reinforcement are detected. March 1994 Pg. 2 of 6 SSP999S19

3 4. Construction 4.1 Timing of Work Installation of anodes shall be done after all concrete patching or concrete overlay operations have been completed. 4.2 Anode Preparation The base and side of anodes shall be given two coats of epoxy resin applied not less than 24 hours before they are placed in the structure. Adhesive tape shall be applied to the top face of the anodes and left in place until the conductive mix is to be placed. 4.3 Location Anode locations shall be accurately marked on the deck as indicated in the Contract. A covermeter shall be used to determine reinforcing bar locations; the final anode location may be moved up to 150 mm in any direction such that the minimum number of reinforcing bars are cut in making the recess. Where the concrete cover to the reinforcing bars is greater than 50 mm, the anode recesses do not require cutting of reinforcing bars. 4.4 Preparation of Recess Anode recesses just large enough to accommodate the anode shall be cut by either of the following methods to provide a recess 50 mm deep with as smooth a bottom as possible: i) Core drill ii) Concrete saw The concrete shall be removed in conformance with OPSS 930. The reinforcing steel shall be cut flush with the hole walls with a cutting torch. The anode recess and saw-cut slots shall be abrasive blast cleaned in conformance with OPSS 930 and air blasted with oil-free compressed air. Immediately upon completion of the cleaning of the anode recess, the ends of any cut reinforcing bars shall be coated with a thick layer of epoxy paste. 4.5 Cable Connection A 6 mm wide x 10 mm deep saw-cut slot shall be made between the junction box location and the anode recess. A self-propelled saw shall be used on bridge decks. The slot entry at the recess shall be rounded off to avoid sharp edges. The anode cable shall be held in place in the saw-cut slots by a non-metallic plug every 600 mm such that the wire does not move towards the surface. The cable lengths provided shall run unspliced from the anodes to the junction boxes. If wire is to remain unconnected at the junction box location for more than one week, a heat shrink boot shall be installed. Wiring slots shall be backfilled with epoxy paste. March 1994 Pg. 3 of 6 SSP999S19

4 4.6 Anode Placement A 12 mm thick bed of epoxy paste shall be placed in the anode recess. The anode shall be supported by insulating spacers to prevent settlement in the epoxy paste. The anode shall be placed such that the lead cable feeds directly into the anode cable slot, and adjusted such that the top of the anode is flush with the concrete deck. 4.7 Recess Backfill After the epoxy has set, the surfaces of the recess around the anode shall be moistened with water prior to backfilling. Any free-standing water shall be removed, and the recess shall be filled with non-shrink grout to the original surface depth in conformance with the grout manufacturer's specifications. If a concrete saw was used to form the recess, all saw-cuts beyond the recess shall be sealed with epoxy paste, flush with the deck. 4.8 Isolation The Contractor shall ensure that the conductive asphalt be electrically isolated from the reinforcing steel and from any metallic components on the surface of the structure. Prior to placement of the conductive mix, the deck surface shall be checked visually and with a holiday detector for exposed metal such as rebar ties or reinforcing steel which is electrically continuous with the deck reinforcing steel. Any such metal shall be insulated with two coats of epoxy resin. 4.9 Junction Box Entry When wiring is to be routed through the curb to junction boxes mounted on the outside face of the deck, concrete shall be removed at the curb and sidewalk locations to the width and depth indicated in the Contract. A hole shall be cored to provide access to the junction box or to provide a deck entry hole where indicated in the Contract. A PVC conduit shall be installed and grouted in place with non-shrink grout. When wiring is to be routed to junction boxes embedded in new barrier walls or sidewalks, a blockout shall be created to permit installation of conduit and wiring. After installation of the cables, the conduit in the curb shall be sealed with a silicone plug to a depth of 50 mm. The cavities in the curb, barrier wall or sidewalks shall be filled with concrete to the original surface in conformance with OPSS 904. Alternatively, the cavity may be filled with non-shrink grout Testing During Installation The AC resistance between the anode lead cable and the cathode CS cable shall be measured at the curb using an AC resistance meter. If the indicated resistance is less than 50 ohms, a short circuit may exist. In this case, the anode shall be removed and reset, with reinforcing bars reinsulated with epoxy paste. The Contractor shall submit results of all tests to the Owner. March 1994 Pg. 4 of 6 SSP999S19

5 4.11 Final Acceptance Testing General Prior to the acceptance of the Work, the Contractor shall demonstrate that all components of the cathodic protection system are in proper working condition and that no short circuits exist between the conductive asphalt and the reinforcing steel. The system shall be energized for a period of 24 hours and the Contractor shall submit the results of all tests to the Owner. When measuring the potential of reference cells and voltage probes, the negative lead of the multimeter shall be connected to the reference cell or voltage probe lead wire and the positive lead to the cathode CM wire. The sign of the reading shall be recorded. If the AC power supply to the cathodic protection system is not in service at the completion of the Contract, acceptance testing shall be carried out using a portable generator supplied by the Contractor Testing Prior to Energizing Cathode Connections The Contractor shall measure the DC resistance and voltage between each pair of lead wires for cathode connections at the control panel. The resistance shall be less than 2 ohms and the voltage shall be less than 1 mv. Anode to Cathode Resistance and Voltage The Contractor shall measure the AC resistance and DC voltage, in mv, between each anode bus cable and the cathode CS wire at the control panel. The resistance shall be less than 3 ohms for each bus connected to 3 or more anodes, less than 5 ohms for each bus connected to 2 anodes and less than 10 ohms for individual anodes. An additional 2 ohms will be allowed for bridge decks with a concrete overlay treatment. Reference Cells The Contractor shall measure and record the voltage potential, in mv, and AC resistance between the reference cell lead wire and the corresponding cathode CM lead wire at the control panel. The resistance shall be greater than 10 ohms but less than 5000 ohms. Voltage Probes The Contractor shall measure and record the voltage potentials and AC resistance between each voltage probe lead wire and a cathode CM lead wire at the control panel. The resistance shall be less than 20 ohms Testing After Energizing The rectifier shall be turned on and tested in conformance with the manufacturer's instructions. The system shall be operated in the constant current mode at a current limit of 2 ma per m 2 of concrete surface area. The accuracy of all meters and proper circuit polarity shall be verified using a multimeter. March 1994 Pg. 5 of 6 SSP999S19

6 After the system has been energized for 24 hours, the potential of all voltage probes and reference cells, and the potential between the anode and cathode shall be measured. Both "on" and "instant off" readings shall be taken. The instant off reading is taken immediately after the current flowing to the system has been interrupted. The system then shall be turned off for 4 hours and additional off readings shall be taken. The system then shall be turned back on and the current output adjusted as directed by the Owner. The off readings between the anode and cathode at the end of the 4 hour off test shall be compared to the static reading taken prior to system start-up. A short circuit exists if the potential between the anode and cathode dropped to the static potential during the 4 hour off period. The short circuit shall be located and eliminated. 5. Measurement for Payment Measurement for payment will be made for each anode by Plan Quantity as may be revised by Adjusted Plan Quantity. 6. Basis of Payment Payment at the contract price for the above item shall be full compensation for all labour, equipment and materials to do the work. March 1994 Pg. 6 of 6 SSP999S19