Corrosion can degrade metals and plastics, impacting productivity and safety in industrial operations. Valves help in controlling the flow of fluid substances, but they are vulnerable to corrosion. The advantages of valve materials in corrosive environments depend on what the valve is made of and the corrosive characteristics of the substance flowing through the valve.
What Is Corrosion and What Causes It?
Corrosion is a natural process that degrades materials due to chemical reactions within their environment. Exposure to moisture, oxygen, chemicals, or even the electrical properties of different metals in contact can trigger corrosion.
Industrial valves and gauges are like the sentinels in the path of flowing material, often facing unanticipated skirmishes with corrosive agents. Whether it’s the steady drip of water causing oxidation or the aggressive assault of industrial chemicals, these devices must endure without conceding.
What’s the Difference Between Corrosion and Rust?
While we’re quick to use the words “rust” and “corrosion” interchangeably, they’re actually different phenomena. Rust is a type of corrosion, but not all corrosion is rust. Rust specifically refers to the oxidation of iron that happens with iron and other metals that contain iron, like steel, are exposed to oxygen and moisture. The chemical reaction between iron and oxygen transforms iron into iron oxide, with its characteristic reddish appearance and flaky texture.
Corrosion includes a broader suite of reactions affecting a variety of metals. While rust is visibly apparent by its color, other types of corrosion might not be visible. These include the following:
- Pitting corrosion is a localized form of corrosion that results in the formation of cavities or “holes” in the material, making it especially hazardous due to its concentrated and unpredictable nature.
- Crevice corrosion occurs in narrow crevices or gaps where stagnant conditions promote corrosion, leading to damage in confined areas.
- Intergranular corrosion attacks the grain boundaries of metal and weakens the structure along these boundaries.
- Stress corrosion is caused by a combination of tensile stress and corrosive environments, resulting in cracking and failure under stress.
- Galvanic corrosion arises due to the contact between dissimilar metals, creating an electrochemical reaction that accelerates corrosion at the interface.
Each type of corrosion poses distinct challenges and requires unique prevention and mitigation strategies to safeguard metals and structures.
Why Are Some Materials More Corrosion Resistant Than Others?
Imagine metals as a group of people with diverse personalities—everyone reacts differently to environmental stimuli. In the same way, factors like atomic composition, electron activity, and the material’s surface stability can influence a metal’s resistance to corrosion.
Some metals can form corrosion-resistant surfaces through the oxidation of one or more of the components of the alloy. For example, stainless steel contains chromium, and chromium oxide forms a protective film on the surface of the metal. The film makes stainless steel “self-healing,” as it will re-form over scratches in the metal.
Other materials might be less resilient, succumbing more swiftly to chemical attacks. No material can resist all types of corrosion, so it is important to match materials with the environment they will endure.
What Are the Dangers of Corroded Valves?
Corroded valves in industrial systems can have a detrimental impact on productivity, quality, and safety. They can become difficult to operate or even get stuck, leading to system downtime, increased maintenance costs, and decreased productivity. Moreover, corrosion can compromise the integrity of valves, potentially causing leaks or failures that affect the quality or integrity of the substance flowing through the valve. This may impact the final product and lead to waste and rework.
Where safety is concerned, corroded valves pose a significant risk of malfunction or failure. This can result in hazardous situations, such as leaks, spills, or even ruptures and explosions, that jeopardize the well-being of workers and the surrounding environment. Addressing valve corrosion by implementing preventive maintenance measures is crucial for upholding efficiency, quality, and safety standards in industrial systems.
What Industries Need Valves That Resist Corrosion?
A breadth of industries require corrosion-resistant valves. Examples include petrochemicals, where a blend of hydrocarbons and chemicals flows daily. Similarly, the marine sector contends with saltwater’s relentless corrosivity. Pharmaceuticals, water treatment facilities, and the food and beverage industries rely heavily on valves that can defy corrosive odds.
Valve Materials That Are Corrosion Resistant in Different Environments
To get an idea of the advantages of valve materials in corrosive environments, consider different types of valve materials and the environments for which they are best suited:
Stainless Steel
The chromium in stainless steel forms a protective film that provides an invisible armor when the stainless steel object sustains damage. Food processing and medical industries choose stainless steel for its durability and hygienic properties. Because it is “self-healing,” stainless steel is unlikely to develop pits or crevices where germs can lurk. It is also easy to clean because of its resilience.
PVC (Polyvinyl Chloride)
PVC plastic doesn’t rust, and it resists the corrosive properties of seawater, some organic solvents, and bases. However, it cannot be used with materials that contain chlorinated hydrocarbons. Still, PVC valves are a common choice for water systems.
Monel
Monel, the alloy of nickel and copper, can handle maritime applications with constant exposure to seawater or in other salty environments.
Inconel
Inconel alloys, comprised mostly of nickel and some chromium, have exceptional corrosion resistance and the ability to withstand high temperatures and pressure.
Titanium
Titanium is highly corrosion resistant, able to endure a variety of chemicals and reactive environments. It also stands up to high temperatures.
Alloy 20
Alloy 20 is a mix of nickel, chromium, molybdenum, and copper. It’s more corrosion resistant than stainless steel and able to endure acidic corrosion, even when exposed to sulfuric acid.
Alloy C-276
Considered one of the most versatile corrosion-resistant alloys available, Alloy C-276 consists of nickel, molybdenum, chromium, and a trace of tungsten. It demonstrates remarkable resilience against numerous chemical environments and is a favorite of chemical industry professionals.
Selecting the right valves based on their intended application and environment requires knowledge of their properties. The advantages of valve materials in corrosive environments depend on the compatibility of the valve material and the substances that will flow past or through it.
Investing in quality, corrosion-resistant valves is essential for safety, operational excellence, productivity, minimizing downtime, and cost-effectiveness. Corrosion-resistant materials last long, need infrequent replacements, and keep fluids moving throughout industrial systems.
DirectMaterial offers a variety of valves, from stainless steel to lead-free brass and more. Browse our collection to find competitively priced valves that work for your intended application.
