What is cathodic protection used for?

Cathodic protection is one of the most effective methods for preventing corrosion on a metal surface. Cathodic protection is commonly used to protect numerous structures against corrosion, such as ships, offshore floaters, subsea equipment, harbours, pipelines, tanks; basically all submerged or buried metal structures.

How long does cathodic protection last?

The life of these systems can be designed to last up to 40 to 50 years, with a typical design life of 25-30. Once the end of life is reached, a new anode will need to be installed, and the system can be returned to use. Overapplication of current from these systems can result in issues with your structure.

Do all pipelines have cathodic protection?

(d) Bare pipelines, breakout tank areas, and buried pumping station piping must have cathodic protection in places where regulations in effect before January 28, 2002 required cathodic protection as a result of electrical inspections.

Which metal is used as sacrificial anode?

Sacrificial anodes generally come in three metals: magnesium, aluminum, and zinc. Magnesium has the most negative electropotential of the three (see galvanic series, right) and is more suitable for on-shore pipelines where the electrolyte (soil or water) resistivity is higher.

What is the purpose of sacrificial anodes?

Sacrificial anodes are metals or alloys attached to the hull that have a more anodic, i.e. less noble, potential than steel when immersed in sea water. These anodes supply the cathodic protection current, but will be consumed in doing so and therefore require replacement for the protection to be maintained.

Is cathodic protection expensive?

In a life cycle cost analysis for an anticipated 100-year pipeline, a comparison of the two methods described revealed that the cathodic protection system could cost approximately 370 times the cost of the polyethylene encasement, and about six times the purchase price of the ductile iron pipe.

What prevents corrosion from pipeline?

Using coatings are one of the easiest ways to protect your pipes against corrosion. Coatings and linings can be used on pipes that are above or underground. They frequently are used in combination with cathodic protection. Some materials that are used to add defense to your pipelines include epoxy and zinc.

What is a rectifier on a pipeline?

A rectifier is an electrical device that converts alternating current (AC), which periodically reverses direction, to direct current (DC). Sustainability seems to be the latest catch-phrase, and cathodic protection (CP) is an important component for the sustainability of many metal structures.

What is a cathodic reaction?

Cathodic reactions are reduction reactions which occur at the cathode. Electrons released by the anodic reactions are consumed at the cathode surface. Unlike an anodic reaction, there is a decrease in the valence state.

What is cathodic testing?

A cathodic protection inspection is the only way to verify sacrificial anode systems are working properly. Sacrificial systems rely on a large number of buried anodes to prevent corrosion. These anodes are attached to the buried steel and over time lose their connection or have lower energy output.

What are examples of sacrificial anodes?

Three metals that can be used as sacrificial anodes are zinc, aluminum, and magnesium.

How do anodes work?

Sacrificial anodes are used to protect metal structures from corroding. Sacrificial anodes work by oxidizing more quickly than the metal it is protecting, being consumed completely before the other metal reacts with the electrolytes.

What happens when cathodic coating breaks?

If the voltage is too high, there will be film rupture of the coating applied to the outer surfaces. This is called the rupture voltage. At a sufficiently high voltage, the current will break through the film, leading to gas generation under the film (hydrogen for cathodic and oxygen for anodic).

Is cathodic protection necessary?

Cathodic protection is an important method of preventing corrosion on buried metal pipelines. Every pipeline operator must carry out regular measurements of CP – at transformer rectifiers and tests points (in impressed current systems) and at sacrificial anodes (in galvanic systems).

What is the meaning of catheterization?

the introduction of a catheter (a hollow flexible tube) into a body cavity or organ to inject or remove a fluid. See also female catheterization, Foley catheter, male catheterization.

What is a right heart catheterization?

Right heart catheterization. This procedure checks the pressure and blood flow in the right side of the heart. A catheter is inserted in the vein in the neck or groin. The catheter has special sensors in it to measure the pressure and blood flow in your heart.

What happens during a cardiac catheterization?

Cardiac catheterization gives doctors important information about the heart muscle, heart valves and blood vessels in the heart. During cardiac catheterization, doctors can do different heart tests, deliver treatments, or remove a piece of heart tissue for examination.