Corrosion Control diimplentasikan dalam berbagai bidang, baik pada logam, tanah, beton concrete, air, batu maupun pasir. Corrosion Control adalah berbagai teknik pemantauan dan pengendalian korosi untuk memecahkan masalah korosi sesuai kebutuhan  dan untuk menghindari konsekuensi negatifnya.

 

Corrosion can lead to countless environmental issues. For example, ships, tankers and pipelines are often subjected to the dangerous corrosion effects. Corroded water systems can also contaminate drinking water. These serve as threats to the environment and mankind, so effective corrosion control methods should be implemented to prevent the damaging effects of corrosion. Corrosion can be controlled in several ways:

  1. Cathodic protection (CP) – This technology utilizes direct current to counteract a metal structure’s corrosion, in structures like gas pipelines and storage tanks. This helps prevent the onset of corrosion and even stop it from worsening.

Cathodic protection is an electrochemical means of corrosion control in which the oxidation reaction in a galvanic cell is concentrated at the anode and suppresses corrosion of the cathode in the same cell. This is achieved by placing a more easily corroded metal to act as the anode of the electrochemical cell in contact with the metal to be protected.

Cathodic protection is also known as a cathodic protection system. Cathodic protection is a procedure used to protect an object from corrosion by making it a cathode. For example, to make a tank a cathode, an anode is attached to it. Both have to be in an electrolyte such as soil or water. Cathodic protection is a widely used method for controlling the corrosion of metallic structures in contact with most forms of electrolytically conducting environments such as soils, seawater and natural waters. Cathodic protection essentially reduces the corrosion rate of a metallic structure by reducing its corrosion potential, bringing the metal closer to an immune state.

Cathodic protection can be achieved in two ways:  The use of galvanic (sacrificial) anodes & Impressed current

Galvanic anode systems employ reactive metals as auxiliary anodes that are directly electrically connected to the steel to be protected. Impressed-current systems employ inert anodes and use an external source of DC power to impress a current from an external anode onto the cathode surface.

Cathodic protection enables the cost effectiveness and safe operation of the grounded and submerged metal structures. It is relatively simple, has proven efficiency and its effectiveness can be monitored continuously. Cathodic protection is the key to protecting and extending the life of metal equipment.

Cathodic protection is one of the few methods of corrosion control that can be effectively used to control corrosion of existing buried or submerged metal surfaces.

Cathodic protection systems are most commonly used to protect:   Steel,  Water or fuel pipelines, Storage tanks,  Steel pier piles,  Ships,  Offshore oil platforms, Onshore oil well casings

Cathodic protection can be, in some cases, an effective method of preventing stress corrosion cracking.

The negative side of cathodic protection is that excessive negative potentials can cause accelerated corrosion of lead and aluminum structures because of the alkaline environments created at the cathode. Hydrogen evolution at the cathode surface may, on high-strength steels, result in hydrogen embrittlement of the steel, with subsequent loss of strength. This may lead to catastrophic failures. It may also cause disbondment of coatings; the coating would then act as an insulating shield to the cathodic-protection currents. It cannot be used to prevent atmospheric corrosion on metals. 

 

  1. Linings and coatings – These serve as the main tools for fighting corrosion. They are usually applied in combination with CP to achieve the highest level and most cost-effective corrosion protection.

Coating, in the context of corrosion, is the thin layers of a covering substance, deposited or applied on a surface of any object, mainly to improve its critical properties and to create a protective barrier against deterioration of the surface due to its reaction with its environment.

When used as a verb, coating is defined as the process of application of covering layers on the surface. The surface on which coating is applied is called as substrate.

The coating protects the substrate from deterioration due to electrochemical reaction with the environment.Thus it improves the useful life of structures, pipelines and other vital equipment, and eliminates some of the life threatening failures and costs related to repair and premature replacements.

 

The term “coating” generally includes 

thin metallic covering,

inorganic lining like glass and porcelain lining,

organic covering such as polymeric material, paint, varnish, and

optical film covering and etched or printed covering.

 

The coating may be applied to provide

abrasion resistance and scratch resistance,

fire resistance and heat resistance

insulation against flow of electric charge

sealing ability and wettability

improved physical appearance and aesthetics

corrosion resistance

resistance against general wear, erosion, pitting and cavitation

improved physical appearance and aesthetics

release or nonstick property

 

Some examples of coating are

The layers of anti rust and anti corrosion paint,

polymeric material and varnish applied on structures and pipelines,

adhesive tapes,

fabrics with waterproof lining,

extrusion coated components and

cermet covered jet engine components.

 

Substrate can be steel and other metals and nonmetals like fabric, paper, plastics and wood. Coatings are extensively used for the protection of pipes and structures buried in the soil and immersed under water, as in the case of offshore oil rigs and platforms and also those installed in corrosive environment.

 

Lining is a layer of material on the inner surface of something, usually for protection or decorative appearance. It may refer to:

Textiles – Material used to line a garment, curtain, etc.

Printing, lithography & bookbinding – Material used to strengthen the back of a book

Civil engineering – Layer of concrete, brick, timber, etc. used in canals to prevent leaking or in tunnels or shafts to prevent cave-ins

Chemical engineering – Material used on the furnace side of a furnace wall. It is usually of high-grade refractory tile, or brick or plastic refractory material. 

 

Linings prevent corrosion in a wide range of difficult applications. Linings offer a number of benefits, including:

Chemical resistance

Low permeability

Physical durability

Economical installation

 

Linings are commonly used in applications such as:

Cylindrical lining, bushing – A cylindrical metal lining used to reduce friction

Furnace lining, refractory – Lining consisting of material with a high melting point, used to line the inside walls of a furnace

Protective covering – A covering that is intended to protect from damage or injury

Strip lining – Thin sheet strips of corrosion-resistant alloy attached by spot welding in the field to protect an unclad vessel

The most commonly used lining materials are polymers, refractories, cement and bricks. Which materials are used for lining depends on the materials and surroundings upon which lining is to be applied.

For example, furnace lining is a protective and insulating layer that serves to protect the furnace parts from the extreme heat developed during smelting operations. It also prevents excessive heat loss from the external furnace surfaces, making the process more efficient. Furnace lining materials are typically ceramics or combination metal/ceramics. These protective layers may be made up of individual bricks, poured fluid aggregates or semi-moist aggregates which are rammed into place.

 

  1. Corrosion inhibitors – These are substances that, when placed in a certain environment, reduce the corrosion rate of that environment to certain materials like metal. These can be beneficial in extending the lifespan of equipment and preventing failures as well as system shutdowns. Corrosion inhibitors can also prevent heat transfer loss, contamination and preserve the aesthetic appearance of the structures.

A corrosion inhibitor is a substance which, when added to an environment in a small concentration, effectively reduces the corrosion rate of a metal exposed to that environment.

There are three types of corrosion inhibitors:  Anodic inhibitors, Cathodic inhibitors, and Mixed inhibitors

 

Corrosion inhibition usually results from one or more of three general mechanisms

The inhibitor molecule is adsorbed on the metal surface by the process of chemisorption, forming a thin protective film either by itself or in conjunction with metallic ions.

The inhibitor causes a metal to form its own protective film of metal oxides, thereby increasing its resistance.

The inhibitor reacts with a potentially corrosive substance in the water.

 

When choosing the corrosion inhibitor for your application, several things need to be considered, as follows:

Materials to be protected

Method of application (dip, spray, brush, etc.)

Type of protection required (in process, storage or shipping)

Type and thickness of coating residue desired

Storage, packaging and/or shipping conditions (temperature, humidity seasonal conditions)

Interaction with subsequent processes, if not removed

Environmental, health and safety requirements

Type of product (oil/solvent or water-based)

 

Electrochemical methods are routinely used for the evaluation of corrosion inhibitor efficiency. The advantages of electrochemical methods are their short measurement time and mechanistic information, which help in the design of corrosion protection strategies, as well as the design of new inhibitors.

 

  1. Selection of materials – This refers to choosing materials that are corrosion resistant like special alloys, plastic and stainless steel to improve the lifespan of structures. (Corrosionpedia, Corrosionindonesia)