Sulfidation corrosion is a type of degradation that occurs when sulfur-bearing compounds react with metal surfaces. In most cases, this reaction leads to the formation of metal sulfides. The resulting metal sulfides are often harder and more brittle than the metal itself, which can cause catastrophic failure in some instances.
Sulfidation corrosion is a significant problem in many industries, particularly those that use fossil fuels. Coal and natural gas, for example, often contain sulfur compounds that can lead to sulfidation corrosion. In this article, we’ll take a closer look at sulfidation corrosion, including its causes, effects, and how you can protect your equipment from this type of degradation.
1. What is sulfidation corrosion?
Sulfidation corrosion is a type of degradation that occurs when sulfur-bearing compounds react with metal surfaces. In most cases, this reaction leads to the formation of iron sulfides. The resulting iron sulfides are often harder and more brittle than the metal itself, which can cause catastrophic failure in some instances.
2. What are the causes of sulfidation corrosion?
There are two main causes of sulfidation corrosion: exposure to elemental sulfur and exposure to hydrogen sulfide gas. Elemental sulfur is found in coal and other fossil fuels, while hydrogen sulfide gas is produced by certain industrial processes.
When elemental sulfur comes into contact with a metal surface, it oxidizes to form sulfur dioxide gas. This gas then reacts with water vapor in the air to form sulfuric acid vapor, which can condense on the surface of the metal and lead to localized corrosion.
Hydrogen sulfide gas is even more corrosive than elemental sulfur. When hydrogen sulfide gas comes into contact with a metal surface, it reacts with water vapor in the air to form sulfuric acid vapor. This corrosive vapor can then condense on the surface of the metal and cause localized corrosion.
The formation of Hydrogen sulfide gas can have both a chemical origin (abiotic) or an biological origin (Biotic). In this case the mechanism is attributed to Microbial Influenced Corrosion (MIC). More specifically, this is one the MIC mechanisms called CMIC.
3. What are the effects of sulfidation corrosion?
Sulfidation corrosion can have devastating consequences for both people and equipment. This type of degradation often leads to premature failure of process equipment and pipelines, which can result in costly repairs or replacements. In some cases, sulfidation corrosion can also lead to safety hazards for people working near affected equipment.
Hydrogen sulfide gas is very reactive and dangerous at low concentrations. Inhalation can result into serious health issues. Another issue is the explosiveness of the gas.
4. How can you protect your equipment from sulfidation corrosion?
There are several ways you can protect your equipment from sulfidation corrosion:
* Use high-quality materials: When selecting materials for process equipment or pipelines, be sure to choose high-quality options that are resistant to this type of degradation. Stainless steel alloy 304L is a good choice for many applications because it contains chromium, which forms a protective oxide layer on the surface of the material that prevents further attack from sulfur compounds.
* Coat exposed surfaces: Another way to protect exposed surfaces from damage is by coating them with an impermeable barrier that prevents oxygen and water vapor from reaching the surface of the metal. In some cases, zinc coatings can provide excellent protection against sulfidation corrosion.
* Use cathodic protection: Cathodic protection involves electrically isolating exposed surfaces from one another so that any potential difference between them is eliminated. This prevents localized areas of high potential from forming on the surface of the metal, which helps prevent or slow down degradation processes like sulfidation corrosion.
Sulfidation corrosion is a serious problem in many industries because it can lead to premature failure of process equipment and pipelines . fortunately , there are ways you can protect your equipment from this type of degradation . by using high quality materials , coating exposed surfaces , or using cathodic protection , you can help prevent or slow down damage caused by sulfidation .
Our specialized partner Mistras within Corrosion Alliance has developed a method to offer comprehensive sulfidation corrosion protection programs. In combination with NEBEST they also offer programs to measure and mitigate Microbial Influenced Corrosion (MIC). They can measure MIC with advanced molecular methods, on site, using the MTEST qPCR testkit.
Comprehensive Sulfidation Corrosion Programs
If you have a successful sulfidation detection program, it will help you avoid problems while also protecting your investment. The engineers and technicians at MISTRAS have many years of experience in dealing with corrosion. We can help reduce the effects that sulfidation corrosion creates – from decreased productivity to unplanned shutdowns.
With a wide variety of non-destructive testing (NDT) techniques, engineering subject matter experts (SMEs), and multiple access strategies, MISTRAS can design and execute an inspection plan that is customized to your facility’s individual requirements.
The way this is usually approached is that an integration is made between expertise in consulting, NDT inspection, mechanical services, data management. This is wrapped together into a formalized program designed specifically for an asset. Although the specifics will change from one asset to another. Generally speaking a sulfidation corrosion protection program is broken into four phases:
- Project Scope, Applicability, and Risk Assessment
- Initial Field Visits
- Field Inspections
Learn more about the Sulfidation Corrosion Programs from MISTRAS. The experts from Corrosion Alliance can support you with your specific questions. You can fill out the form at our portal (Dutch only).