Anodes - Mixed Metal Oxide

Mixed Metal Oxide Expanded Mesh Anodes

Protection For Reinforced Concrete Structures
The intrusion of chloride ions into reinforced concrete structures causes corrosion of embedded metal. This leads to delaminations, spalls, cracks, and eventually structural degradation. Using Corrpro’s mixed metal oxide mesh strip anodes this process is effectively curtailed. The anode is composed of an expanded titanium mesh strip, which is coated with a mixed metal oxide catalyst. The titanium substrate is inherently stable and resilient, allowing the anode to be easily installed and assuring that a strong bond remains over the life of the impressed current system. The mixed metal oxide catalyst makes the anode extremely conductive and is the means for transferring electrical current from the titanium to the concrete electrolyte. The anode can be operated at a maximum current density of 20 mA/ft2 with a minimal consumption rate. The special mesh style configuration also permits the anode to have a very low electrical resistance.

To make a cathodic protection system an economical alternative for rehabilitating a reinforced concrete structure, it must be easy to install. Flexible, lightweight, and packaged in manageable strips, Corrpro’s mesh anode is the most installer friendly material available. The strips are shipped flat, and can be easily attached to a reinforced concrete structure with plastic anchor pins. Positive power connections are made by spot welding the strips in a designated zone to a bare titanium conductor bar, which is placed perpendicular to the strips. After negative return connections are made, the anode is covered with an overlay and is ready for energizing.

Typical Applications
Corrpro mesh strip anodes can be used on bridge decks, parking garages, piers, wharfs, or similar reinforced concrete structures. The anode can be installed on new or rehabilitated structures and requires minimal anchoring. Because anode spacing is easily adjusted, a custom cathodic protection system can be designed to zddress the special needs of a particular protection project. This added flexibility also means special cuts around drains, metal edging, and other obstacles can be avoided, thus saving time and labor costs.

Chemical Composition

Element	Content %
ASTM B-265	Mixed
Grade 1 Titanium	Metal Oxide

Mixed Metal Oxide Probe Anodes

Rugged And Easy To Install
Mixed-metal-oxide anodes have very low consumption rates (under 1.0 mg/amp-yr.), and can be operated at high current densities (approximately 10 amps/ft.2 in freshwater and over 50 amps/ft.2 in saltwater). Because of these impressive performance capabilities, Corrpro manufactures mixed-metal-oxide probe anodes for use in heater treaters, condenser water boxes, and pressure vessels. The anodes are composed of titanium rods, which are covered with a mixed-metal-oxide coating. The titanium is inherently resilient and stable, allowing the probe anodes to withstand water turbulence without damage. Because the titanium does not discharge current, electrical current transfer is accomplished through the mixed-metal-oxide coating. The coating is immune to abrupt current reversals, and may be exposed to high-current overloads for initial structure polarization without causing harm to the anode.
Unlike sacrificial anodes, which must be installed within tanks or other vessels, Corrpro probe anodes are designed for mounting and replacement through the wall of the vessel. The anodes are attached to a threaded stainless steel pipe, which is filled with a watertight sealant. To provide a high-pressure connection, the anodes are bonded with G-10 fiberglass, and pressure tested prior to shipping. The fiberglass restricts water flow and lends extra support to the anode. Lead wire connections are made in a cast metal junction box. The box attaches to the stainless steel threaded pipe once the anode is securely in place. The anodes are also adaptable for mounting while the pressure vessel is in service.

Typical Applications
Probe anodes are designed for use in heater treaters, pressure vessels, condenser water boxes, and other process tanks. The anodes deliver superior protection in fresh, brackish, or saltwater. They have been found to be resistant to acid attack, and can withstand temperatures up to 347°F. The anodes should not be used in electrolytes containing barium or cadmium.

Chemical Composition

Substrate	Catalyst
ASTM B-348	Mixed Metal Oxide
Grade 1 Titanium

Mixed Metal Oxide Ribbon Anodes

Protection For Aboveground Tank Bottoms
Cathodic protection is an economical method for controlling corrosion on aboveground storage tank bottoms. While sacrificial systems can be used, impressed current designs have proven to be more effective and easier to install. To address this particular application, Corrpro manufactures impressed-current tank bottom anodes that employ a patented grid-shape geometry. The anodes are composed of a titanium-ribbon substrate coated with a mixedmetal- oxide catalyst. Because the titanium substrate is naturally passivated by an oxidizing film, the ribbon anode remains dimensionally stable over time. Direct current transfer is accomplished through the mixed-metal-oxide catalyst, which is highly conductive, and fully oxidized so that higher current outputs are possible. This two-part composition allows for a maximum current density of 5.0 mA/ft. to achieve a 50-year design life.

In addition to compositional advantages, the unique configuration of Corrpro's anodes offers numerous other benefits. Spacing between the metal anode strips can be adjusted to achieve various design-life requirements. The anodes can also be easily cut so that placement may be made under all areas of the tank. Because the strips are electrically continuous, multiple paths are available for current flow. This in turn lowers the riving voltage required for protection, and provides the anode with redundant electrical connections for increased reliability. Greater dependability is also achieved through the elimination of all field splices.

Typical Applications
Corrpro's mixed-metal-oxide ribbon anodes are designed for use on both newly constructed aboveground storage tanks with secondary containment liners, and existing tanks utilizing double-bottom construction. Unlike other impressed-current tank bottom anodes, Corrpro's ribbon anodes do not require coke breeze. They can be used in sands with various levels of moisture and salt contents, and can be designed to provide effective protection for 50 years and more.

Chemical Composition

Substrate	Catalyst
ASTM B-265	Mixed Metal Oxide
Grade 1 Titanium

Mixed Metal Oxide Solid Rod Anodes

Lightweight And Easy To Install
The use of large and heavy impressed-current anodes has traditionally been thought to be the only method for protecting numerous types of buried and submerged structures. However, with the development of the mixed metal oxide anode, this notion has been greatly challenged. The anodes are small, lightweight, and can operate at current densities much higher than conventional impressed-current anodes (approximately 10 amps/ft.2 in soil and freshwater, and over 50 amps/ft.2 in seawater). In addition, the mixed metal oxide coating on the anodes has an almost negligible consumption rate of less than 1.0 mg/amp-yr. Corrpro manufactures a full line of solid mixed-metaloxide anodes for use in a variety of environments. The anodes are composed of titanium rod substrates, which are coated with a mixed-metal-oxide catalyst. The titanium rod is inherently stable, thus the transfer of direct electrical current is performed through the mixed-metal-oxide coating. The end result is a high-performance anode with an extremely long life.

As with any impressed current anode, a reliable lead wire connection is critical to the operating performance of mixed-metal-oxide anodes. On Corrpro solid rod anodes, a crimped wire connection is made using twelve tons of hydraulic compression. The crimped connection is then covered with two types of moistureresistant mastic tapes and sealed with a heat shrink sleeve. This extremely reliable connection has proven to prevent electrical breakdowns and produce a low resistance of under 0.004 ohms.

Typical Applications
Corrpro rod anodes perform well in all types of environments. Their mixed-metal-oxide coating prevents substrate attack in even highly acidic environments. The anodes have been used with great success in deep and conventional groundbeds, and in fresh, brackish, and saltwater electrolytes. Corrpro supplies the anodes either bare or in canisters containing petroleum coke breeze. For aqueous environments, the anodes can also be provided in a specially designed PVC perforated tube that directs current flow and provides extra protection to the anode.

Chemical Composition

Substrate	Catalyst
ASTM B-348	Mixed
Grade 1 Titanium	Mixed Oxide

Mixed Metal Oxide Tubular Anodes

Dimensionally Stable in All Environments
To obtain the highest level of protection from an impressed current cathodic protection system, you need an anode with a very low consumption rate and high current capacity. With Corrpro’s tubular mixed metal oxide line of anodes, you get powerful protection and unsurpassed stability. The anodes are made using tubular titanium substrates, which are coated with amixed metal oxide catalyst. The catalyst is thermally applied to the titanium to form an extremely chemical-resistant bond. This special composition brings together the stability of titanium with the conductive properties of the mixed metal oxide catalyst to achieve superior performance. In soil and fresh water applications, the anodes have a recommended current density of approximately 10 amp/ft.2, and can be operated over 50 amp/ft.2 in sea water environments. Even at these relatively high discharge levels, the anodes will be consumed at less than
1.0 mg/amp-yr.

The tubular design of these anodes also allows for numerous performance benefits. The tubular configuration provides a larger surface area, which in turn permits greater current output and lower anode-to-earth resistance. The tubular style also means lead wire connections can be made in the center of the anode. With Corrpro tubular anodes, this connection consists of a brass wedge connector, which grips firmly to the internal circumference of the anode. This connection is protected from moisture intrusion by a waterproofing sealant, which fills the entire anode tube. The ends of the anode are then covered with shrink tubing for a completely sealed electrical connection.

Typical Applications
Mixed metal oxide anodes have proven to operate effectively in all types of environments, including areas with extremely low pH levels (under 1), and high chloride concentrations. While Corrpro tubular anodes can be used singularly, their unique configuration also makes them ideal for use in strings on offshore platforms or in deep groundbeds. In addition, the string anodes can be installed parallel to transmission pipelines, or used for other special applications.

Chemical Composition

Substrate	Catalyst
ASTM B-338	Mixed
Grade 1 Titanium	Mixed Oxide

Mixed Metal Oxide Wire Anodes

Lightweight And Dimensionally Stable
The many benefits obtained by using mixed metal oxide anodes are well known. These include low consumption rates, dimensional stability, and high current densities. Wire mixed metal oxide anodes possess all these characteristics and also offer greater installation flexibility. The anodes are composed of a copper core, which is surrounded by a titanium substrate. Metallurgically bonded to the substrate is a mixed metal oxide coating. The combination of these three materials produces an anode capable of superior operating performance. The titanium is inherently resilient and stable, allowing the wire anode to be extremely flexible. Because this metal does not discharge current, electrical current transfer is accomplished through the mixed metal oxide coating. The coating is immune to abrupt current reversals, and may receive high current overloads for initial polarization without causing harm to the anode.
Corrpro wire anodes can be used in numerous geometries. In water storage tanks, the anode is often suspended by rope in configurations that follow the circumference of the structure. This design permits even current distribution. It also produces a cathodic protection system that is not susceptible to damage from icing. Because the anode is a continuous wire, failures due to poor wire connections are eliminated.

Typical Applications
Corrpro mixed metal oxide anodes can be used in both aqueous and soil electrolytes. They deliver superior protection in fresh, brackish, or saltwater, and have been found to be resistant to acids and chloride ions. The anodes can operate in temperatures of up to 175°C. They should not be used in electrolytes containing barium or cadmium.