AREMA COMMITTEE 8. Letter Ballot Number

Transcription

1 AREMA COMMITTEE 8 Letter Ballot Number Attached is a copy of the proposed addition to Part 1 of Chapter 8, regarding new section 1.27 Cathodic Protection and C 1.27 commentary. Please review the attached copy, supplying additions, comments, and revisions. All Committee 8 members should cast their ballot. The participation of every member is important. Your prompt response to this ballot is requested. It is imperative that Members cast their vote. Voting online using the AREMA Communities site is required unless special circumstances, approved by the Committee Chairman, warrant special consideration. See attached document for instructions on how to vote online. Votes on this Letter Ballot are due by November 24, See instructions on the next page for voting online using the AREMA Communities site. Please do not vote both online and via a separate ballot (below) sent to the Committee Chairman. In the case of special circumstances, please complete the ballot below and return it to the Subcommittee 3 Chairman indicated below on or before November 24, Ted Niemeyer, P.E, Committee 8 Subcommittee 3 Chairman V3 Companies 7325 Janes Ave., Woodridge, IL Office: , Cell: , Fax: tniemeyer@v3co.com LETTER BALLOT NUMBER I have reviewed the proposed copy of additions to Chapter 8 of the AREMA Manual, which was attached to this Letter Ballot, and vote as follows: APPROVED APPROVED AS NOTED DISAPPROVED ABSTAIN Your comments will be recognized. Your reason for disapproval must be explained. Your reason for abstaining must be explained. Date: Signature Print Name Prepared:

2 1.27 CATHODIC PROTECTION The two systems used for cathodic protection of steel reinforcement are: a. A galvanic cathodic-protection system, in which a metal dissimilar to steel (usually zinc) encapsulated in an activating mortar or solution is connected to the reinforcing steel to provide protection from future corrosion. A galvanic cathodic-protection system is comprised of individual anodes, distributed anodes, or surface-applied anodes. b. An impressed current cathodic-protection (ICCP) system, in which an external power source supplied through an AC/DC conversion rectifier is applied to the reinforcing steel to protect it from future corrosion. Impressed current cathodic protection is comprised of titanium anodes, individual discrete anodes, or surface-applied conductive coating anodes CATHODIC-PROTECTION SYSTEM DESIGN AND PERFORMANCE 1 Design the cathodic-protection system to achieve the protection performance required for the project in accordance with the structural drawings and required by project specifications. Design calculations and system layout sealed by a licensed professional engineer, with National Association of Corrosion Engineers (NACE) Cathodic Protection Level 4 Certification for the cathodic protection system, shall be submitted to the Engineer for approval PRODUCTS All products for each cathodic-protection system for each project shall be supplied as a system from one manufacturer. 1 See Commentary a. Impressed Current Cathodic Protection (1) Titanium Anodes: A titanium anode is a positively charged electrode made from the chemical element titanium with an activated precious or mixed metal oxide coating. (a) Titanium Ribbon Anodes: A titanium ribbon anode comes in the form of a ribbon with varying widths from ½ inch to 2 inches (13 to 50 mm) and in different thicknesses. The determination of the sizes of the ribbon is part of the cathodic-protection system design. (b) Titanium Mesh: Titanium mesh is an expanded mesh of titanium with an activated precious or mixed metal oxide coating, that comes in the form of sheets with varying widths from 2 feet to 4 feet (600 to 1200 mm) and in different thicknesses. The determination of the layout and sizes of the mesh is part of the cathodic-protection system design. The mesh is attached to the concrete surface, usually with plastic anchors and then protected with a cementitious type overlay.

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4 (2) Discrete Anodes: A discrete anode is specifically designed utilizing an innovative ceramic/titanium composite, combined with an integral gas venting system. The anode system includes a specifically designed high density, acid buffering grout used for long-term performance. The discrete anode is designed to provide protection to a specific location. (3) Conductive Coating Anodes: A conductive coating anodes is a specialized coating which is applied to the surface of the concrete to act as the anode in an ICCP system. It is mostly used on bridges and parking structures. b. Galvanic Corrosion-Protection System (1) Galvanic anodes for Repairs: A sacrificial anode that utilize a zinc anode core surrounded by a specially formulated cement-based mortar to provide corrosion mitigation to immediately surrounding patch repairs for reinforced concrete structures. Once installed, the zinc anode corrodes preferentially to the adjacent reinforcing steel, thereby providing galvanic corrosion prevention or corrosion control. (2) Galvanic anode for existing concrete: A sacrificial anode that is an embedded galvanicdiscrete anode unit used to control on-going corrosion and to prevent the initiation of new corrosion activity in reinforced concrete structures. It is comprised of the zinc anode core surrounded by a formulated cement-based mortar. The cylindrical unit is available in a variety of standard and custom sizes, and installed into concrete that is mechanically sound but has on-going corrosion activity. (3) Galvanic anodes for cast-in-place concrete: A Distributed Anode System (DAS), consists of sacrificial anodes that are furnished as a long narrow anode in variable lengths, generally up to 8- feet (2.4-m) long. They are installed in new overlay concrete to provide corrosion control or full cathodic protection. (4) Surface applied galvanic anodes c. Arch sprayed zinc is metalized zinc that is applied to the concrete surface through an arcwelder to act as a sacrificial anode. It is used to provide corrosion protection to structures such as: bridges, marine structures, and parking structures. In areas of medium to low humidity, an activating humectant is used to keep the zinc active. d. Zinc sheet is a type of sacrificial galvanic anode that is a sheet of zinc with a conductive adhesive which is applied directly to the concrete surface. They are available in various widths and lengths.

5 EXECUTION OF WORK a. Installation of a cathodic-protection system shall be performed by experienced installers. Installers shall have experience and the written consent of the cathodic-protection system manufacturer. b. Installation shall be in accordance with the cathodic-protection system manufacturer s requirements Inspection and Testing a. The field inspector shall observe adherence to cathodic-protection system designer s installation requirements. 2 b. The field inspector shall observe all aspects of the installation. c. Testing shall be in accordance with the cathodic protection system designer s requirements. 1 See Commentary 2 See Commentary

6 COMMENTARY C CATHODIC-PROTECTION SYSTEM DESIGN AND PERFORMANCE The cathodic-protection system must meet the performance requirements of the cathodicprotection system designer as indicated at all identified locations in the cathodic-protection system drawings and performance specification. The design of the cathodic protection system should be completed by a qualified Cathodic-Protection System engineer with NACE Cathodic Protection Level 4 Certification follow the design guides from the NACE guideline for impressed current systems NACE SP Impressed Current Cathodic Protection of Reinforcing Steel in Atmospherically Exposed Concrete Structures and for sacrificial systems the NACE SP Sacrificial Cathodic Protection of Reinforcing Steel in Atmospherically Exposed Concrete Structures. The cathodic-protection system shall be designed consistent with long-term durability exposure testing. C EXECUTION OF WORK b. All products for each Cathodic Protection System shall be designed and supplied as a system. (1) Impressed Current Cathodic-Protection System: The ICCP system consists of the anode electrically connected to the positive (+) side of a direct current (DC) power supply (an AC/DC rectifier), and the reinforcing steel to be protected being connected to the negative (-) side of the DC power supply. Once the system is energized electrons flow from the DC power supply to the reinforcing steel (providing the cathodic protection) and the circuit is completed with negative ions flowing through the concrete to the anode. (a) Titanium Ribbon: Embedded into slots cut into the concrete surface using a grout that has been proven to be conductively effective and resistant to by-products created with titanium ribbon anode is energized. (b) Titanium Mesh: Attached to the concrete surface using plastic anchors and then encapsulated in a concrete overlay (poured in place, shotcrete, or other specialized mortar) that has been proven to be conductively effective and resistant to by-products created when the titanium mesh anode is energized. (c) Discrete Anodes: Are embedded into holes drilled into the concrete surface using a grout that has been proven to be conductively effective and resistant to by-products created when the titanium ribbon anode is energized.

7 (d) Conductive Coating: Is applied to the concrete surface and then connected to the DC power supply. (2) Galvanic Cathodic-Protection System C (a) Galvanic anodes for Repairs: Are connected to the reinforcing steel around the perimeter of the repair by means of steel wires. As the zinc corrodes it supplies protective electrons to the reinforcing steel just outside of the repaired area. (where corrosion will be accelerated due to the repaired area becoming more cathodic, this is known as the Ring Anode Effect or Halo Effect ). The size and spacing of the anodes is determined by the cathodic-protection system design. (b) Galvanic anode for existing concrete: Are embedded into holes drilled into the concrete surface using a grout that has been proven to be conductively effective and then connected to the reinforcing steel in the surrounding area by means of steel wires. As the zinc corrodes it supplies protective electrons to the adjacent reinforcing steel. The size and spacing of the anodes is determined by the cathodic-protection system design. (c) Galvanic anodes for cast-in-place concrete: Are connected to the reinforcing steel inside of a new overlay by means of steel wires. As the zinc corrodes it supplies protective electrons to the reinforcing steel in the adjacent existing concrete. (where corrosion will continue and possibly accelerate due to the reinforcing steel in the new overlay becoming more cathodic than the existing reinforcing). The size and spacing of the anodes is determined by the cathodic-protection system design. (d) Surface applied galvanic anodes i Arc s pray zinc is metalized zinc that is spray applied to the concrete surface through an arc-welder then connected to the reinforcing steel in the concrete being coated by means of steel wires. As the zinc corrodes it supplies protective electrons to adjacent reinforcing steel. In areas of medium to low humidity an activating humectant is applied to the zinc to keep the zinc active. ii Zinc sheets that are applied to the concrete surface adhered by means of a conductive adhesive then connected to the reinforcing steel in the concrete being covered by means of steel wires. As the zinc corrodes it supplies protective electrons to the adjacent reinforcing steel. INSPECTION AND TESTING a. The field inspector should observe and keep daily records to determine and document compliance with the cathodic-protection system design.