• Galvanic System Equipment

In this type of application the naturally occurring electrochemical

potentials of different metals are used to provide protection.

Sacrificial anodes are coupled to the structure under protection and conventional current flows from the node to the structure as long as the anode is more “active” than the structure. As the current flows, all the corrosion occurs on the anode which “sacrifices” itself in order to offer protection from corrosion to the structure.

The galvanic series for common metals is shown below Table. On the active side of the drawing the metals such as zinc, aluminum and magnesium appear. These metals and their alloys are the most commonly used sacrificial anodes

 

 

 

 

 

  • Magnesium Anode

Magnesium  Anode  is  used  for Temporary  protection  of  buried pipelines,  protection  of  well  coated buried  pipelines,  and  protection of small marine structures, “Hot spot” locations for buried & Submerged steel structures, Protection of well coated buried pipelines,  internal  protection  of  water  tanks,  pipeline  casing sleeves. Suitable for use in soils, mud, fresh water, brackish water and sea water. Magnesium anodes are classified into two categories in terms of chemical composition and type of application:

1) Standard Magnesium Anode (AZ63)

2) High potential Magnesium Anode (M1C)

  • Zinc Anode

Zinc has been used as a sacrificial anode material in seawater since 1824. Modern zinc anodes used for Cathodic Protection are cast from high purity zinc (99.99%) alloyed with aluminum and cadmium with limitations on the level of lead, iron and copper.

Typical applications include, submarine pipelines, ballast tanks, offshore structures, storage tank internals, quay walls, water tanks, marine applications and ships hulls.

Zinc anodes are classified in terms of chemical composition and application type in two categories: 1) Zinc Sea Alloys (Type I) designed for use in seawater.2) Zinc standard alloy (Type II), which is formulated into fresh water and soil.

 

  • Aluminum Anode

Aluminum alloy anodes have been formulated primarily for use in seawater. Alloys are also capable of achieving high output capacity in mud and brackish water of resistivity up to 150 Ohm.cm. Aluminum anodes have approximately three times the capacity of Zinc alloys.