Without intervention, valve corrosion can cause leakage, outages and shortened service life. Valve coatings exist to protect internal and external surfaces, and, when properly applied, improve reliability and extend service life.
What is Valve Corrosion?
Valve corrosion occurs when metal surfaces react with their surrounding environment. This reaction can take many forms, including pitting, oxidation, crevice corrosion and general material loss. Common contributors include corrosive chemicals, water ingress, oxygen exposure and elevated temperatures. As corrosion progresses, valves may experience reduced sealing performance, increased operating torque or structural weakening. These effects raise safety risks and increase valve maintenance demands.
Why Valve Coatings Are Used
Valve coatings act as a protective barrier between the base metal and the process environment. By isolating valve surfaces from corrosive media, coatings reduce direct chemical attack and slow material degradation. Coated valves can often outperform uncoated designs in severe service, particularly in applications with aggressive fluids or frequent cycling. Over time this protection lowers repair frequency, reduces downtime and improves overall system reliability.
Where Valve Corrosion Occurs
Valve corrosion is common in O&G operations as well as power generation, mining and minerals processing, chemical processing and water systems.
These services combine corrosive media with operating conditions that place steady stress on valve components.
Field note: Corrosion damage is rarely uniform. In many valves, the earliest signs appear at sealing edges and transition areas rather than on flat surfaces.
Types of Valve Coatings
- Epoxy coatings are used for general corrosion resistance on internal cavities and external surfaces. These coatings act as a barrier against moisture and mild chemical exposure.
- PTFE and fluoropolymer coatings are used for chemical resistance and reduced friction. These coatings perform well in services involving aggressive media and frequent cycling.
- Metallic coatings are used where erosion and mechanical wear occur alongside corrosion. Hardfacing is one example, often used in severe service to extend component life beyond bare metal and allow refurbishment instead of replacement. Learn more on hardfacing solutions for erosive and corrosive service.
- Ceramic-based coatings are used in high temperature service where traditional coatings may degrade. These coatings resist oxidation and surface breakdown under thermal stress.
Matching Coating to Service
Coating selection should consider process chemistry, operating temperature and pressure. A coating that performs well in one service can fail early in another if conditions are mismatched.
How Valve Coatings Protect Against Corrosion
Valve coatings protect against corrosion mainly by limiting direct contact between corrosive agents and the base metal. When the coating is intact, corrosive agents have limited access to the base metal. Some coatings also resist abrasion and erosion from high velocity flow or entrained solids. Stability under temperature and pressure changes is also important. A coating that cracks or flakes under normal operation will not provide long term protection.
Keep in mind that coatings do wear over time. Periodic inspection helps determine when recoating makes sense and when replacement is the better option. Once corrosion reaches the base material, repair options become more limited. Catching coating wear early can prevent damage to the base valve material.
Speak with a Valve Specialist to Review Coating Options Today
ValvTechnologies is a global manufacturer of metal seat ball valves, coking valves, trunnion ball valves, slurry valves, switching valves, and parallel slide gate valves. We work directly with engineers and operators to apply valve coatings that perform in real service conditions. Coatings are selected as part of the valve design process, based on how the valve will operate, what it will see in service and how long it is expected to run. This comes from decades of experience with severe corrosion and coating solutions that help valves perform as intended over time. Learn more about our high velocity oxygen fuel coating process.
Questions? Contact us today to learn more about our portfolio of valve solutions.