What Causes Corrosion?
Corrosion occurs when a chemical reaction takes place in an environment that surrounds materials and starts to cause slow deterioration and weakening of the material. Certain gasses from an environment that contact a certain metal ultimately determine the rate and form of corrosion. It’s important to understand what affects wire corrosion to prevent deterioration.
Corrosion is a major concern when burying cable lines underground because the elements, as well as the earth’s electrical charge, can cause degradation of their mechanical integrity over time. To protect metallic structures from corrosive processes in various environments, cathodic protection systems are set in place.
What are HMWPE and Cathodic Protection?
High molecular weight polyethylene (HMWPE) is used to insulate cables for cathodic protection, which means it resists moisture, abrasion, and corrosive chemicals. It works by converting the anodic (active) sites on the metal surface, by use of electrical current, to cathodic (passive) sites. If the current arrives at the cathode faster than oxygen does, which slows down or completely prevents corrosion. HALAR and KYNAR corrosion-resistant cables at Performance Wire and Cable are long-lasting because of this technology.
HALAR/HMWPE cables are dual-insulated, which allows superior resistance to chemicals, abrasion, and crushing.
KYNAR/HMWPE cables can do everything a HALAR cable can but can additionally withstand corrosion from chlorine, sulfuric acid, and hydrochloric acid.
Where Corrosion-Resistant Wire Is Needed
Buried or water-submerged instances, HALAR and KYNAR corrosion-resistant wires provide cathodic protection in these settings:
- Storage Tanks
- Steel Pilings
- Well Casings
- Water Towers
- Marine Craft
9 Most Common Types of Wire Corrosion
These are the most common types of wire corrosion and what they look like:
1. General Attack Corrosion
This form of corrosion happens when a chemical or electrochemical reaction causes the deterioration of the exposed metal surface. Although general attack corrosion is the most prominent form in metals, it is also considered the safest in that it’s often a predictable, manageable, and often preventable form of wire corrosion.
2. Localized Corrosion
This type of corrosion is localized, targeting just one area on a metal structure. There are three different categories: pitting, crevice, and filiform.
- Pitting – the result of corrosion causing a small hole (pit) in the metal, which is usually hard to find because of its small nature. The pitted area becomes anodic, while part of the remaining metal becomes cathodic, producing a localized galvanic reaction.
- Crevice – this happens in a crevice, which is due to a lack of oxygen or an overly acidic area. It’s typically found around gaskets, washers, and clamps.
- Filiform – can ultimately lead to structural weakness. It starts when water seeps through painted or plated surfaces or anywhere there may be a defect in a surface coating.
3. Galvanic Corrosion
Galvanic corrosion occurs if two electrochemically different metals occupy the same space that is in electrical contact with one another, and the metals are exposed to an electrolyte. It happens rapidly to the less corrosive-resistant metal, becoming anode, whereas the more corrosive-resistant metal decreases, becoming cathode.
4. Environmental Cracking Corrosion
Environmental cracking wire corrosion is sometimes referred to as stress corrosion cracking, corrosion fatigue, hydrogen corrosion, or liquid metal embrittlement. It happens when certain chemical, temperature, or stress-related conditions affect the metal. The two most common causes are brass’s seasonal cracking and steel’s caustic embrittlement.
5. Flow-Assisted Corrosion (FAC)
This corrosion is caused by the wind or water “washing away” the metal surface’s protective layer of oxide, known as the passive layer, to break down. Once the metal is exposed, the underlying metal to the corrosive fluid causes further corrosion. FAC can be prevented or minimized through a variety of measures, such as using corrosion-resistant materials, controlling the fluid velocity and temperature, and implementing proper maintenance and inspection procedures.
6. Intergranular Corrosion
An electrochemical attack on the grain boundaries of metal is what is known as intergranular corrosion. This often occurs due to impurities at the grain boundaries, enrichment of one of the alloying elements, or depletion of one of these elements near the grain boundaries.
7. Selective Leaching Corrosion
This occurs when one element from a solid alloy is removed due to corrosion. Selective leaching most commonly happens when there is a selective removal of zinc in brass alloys, also known as dezincification.
8. Fretting Corrosion
Repeated wearing, weight, and vibration on rough or uneven surfaces and asperities of contact surfaces cause this type of corrosion. Impact machinery, bolted assemblies, and bearings often see fretting corrosion and surfaces that experience heavy vibration. Failure to properly address fretting corrosion can result in reduced equipment lifespan, loss of functionality, and potential safety hazards.
9. High-Temperature Corrosion
This corrosion can be caused by oxidation in high temperatures, sulfidation, and carbonization. More commonly, high-temperature corrosion exists in gas turbines, diesel engines, and other machinery. During combustion, corrosion will occur when vanadium or sulfates form compounds at a low melting point. The composites are corrosive to metal alloys that are otherwise resistant to high temperatures and corrosion.
Leading Global Manufacturer and Supplier of Cathodic Protection and Corrosion-Resistant Cable and Wire
Performance Wire and Cable is proud to be an official member of NACE, the leading authority on corrosion control solutions. We work directly with other NACE members to ensure our products are of the highest quality.
We provide the highest quality wire and cable products and can customize our products to meet the needs of any sized business. Our knowledgeable team will help with every step of the ordering process.
Ready to stock up on all your Corrosion-Resistant Cable and Wire?
Performance Wire & Cable is here for you! Get a quote today.