Checking (corrosion)

Checking (Corrosion) in Oil & Gas: A Silent Threat to Infrastructure

In the demanding environment of the oil and gas industry, materials are constantly under attack from corrosive elements. One specific form of corrosion, known as checking, poses a significant threat to infrastructure integrity and safety.

What is Checking?

Checking refers to slight breaks or cracks in a surface coating that do not penetrate to the underlying material. These cracks are typically fine, hair-like lines that can extend across the surface of a coating. While these breaks may appear insignificant, they can compromise the protective barrier of the coating, allowing corrosive elements to penetrate and attack the underlying metal.

Causes of Checking:

Checking can be caused by a variety of factors, including:

• Stress: Thermal expansion and contraction of the coating, due to temperature fluctuations, can cause stress that leads to cracking.
• Poor adhesion: If the coating is not properly adhered to the surface, it can crack under stress or during normal wear and tear.
• Underlying surface defects: Scratches, imperfections, or other defects on the surface of the material can act as stress concentrators, leading to checking.
• Chemical attack: Certain chemicals in the environment can attack the coating, leading to degradation and cracking.

Why is Checking a Problem?

While checking might appear minor, it can have serious consequences:

• Increased corrosion: Checking allows corrosive elements to reach the underlying metal, accelerating the corrosion process.
• Reduced coating lifespan: The protective barrier provided by the coating is weakened, significantly reducing its lifespan.
• Potential for catastrophic failure: In severe cases, checking can lead to complete failure of the coating, exposing the underlying metal to severe corrosion and potentially leading to leaks or structural damage.

Preventing and Managing Checking:

Managing checking is crucial for ensuring the long-term integrity of oil and gas infrastructure. Some important measures include:

• Proper surface preparation: Ensuring the surface is clean, free of defects, and properly prepared before applying the coating.
• Using high-quality coatings: Choosing coatings that are resistant to the specific corrosive environment and have good adhesion properties.
• Regular inspections: Regularly inspecting coatings for signs of checking and taking prompt action to repair or replace damaged coatings.
• Maintaining appropriate environmental conditions: Controlling temperature fluctuations and minimizing exposure to corrosive chemicals.

Conclusion:

Checking may seem like a minor issue, but its potential consequences can be significant. Understanding the causes, risks, and preventative measures associated with checking is essential for ensuring the safety, reliability, and longevity of oil and gas infrastructure. By taking proactive steps to prevent and manage this form of corrosion, operators can avoid costly repairs and downtime, ultimately enhancing safety and operational efficiency.