Consider This When Prepping an Oil Tank for Surface Coating

Proper oil tank surface coating preparation is the most important step of the coating process, as premature failures are often the result of inadequate preparation. Because of the size of the tanks, the constant threat of moisture and adverse weather, challenging logistics and tight schedules, preparing an oil tank for a surface coating may seem like a daunting task. By knowing what factors to consider and monitor during the preparation stages, you’ll help ensure a successful coating application.

Oil Tank Surface Coating Preparation Considerations

• Cleanliness: The cleanliness of a substrate directly affects a coating’s performance. Any substance that negatively affects how the coating adheres to a substrate is a contaminant. Common contaminants include:
  • Oil and grease
  • Moisture
  • Salts
  • Oxidation
  • Ionic species in the environment
  • Weld spatter
  • Dust and particulates
  • Welding and cutting fumes
  • Burn-through from welding on the opposite side of a surface

The best way to clean an oil tank depends on the tank’s age, the type of coating it previously had and the contaminants in question. Common cleaning methods include abrasive blasting and the use of solvents.

• Temperatures and relative humidity levels: As you work to remove rust and other contaminants, the elements may work against you if ambient conditions are not ideal. In addition to air temperatures, surface temperatures are an important consideration, as surfaces tend to absorb heat during the day and radiate it at night. Depending on relative humidity levels, temperature changes in the air or on the substrate may lead to the formation of condensation on the substrate. High humidity levels may also result in flash rust in as little as 30 minutes.
• The time between cleaning and coating: For a successful oil tank surface coating preparation and application, you must control and monitor ambient conditions from the time you begin cleaning to at least 48 hours after the final coating application. After your team finishes cleaning the tank, it’s vital to maintain ideal ambient conditions so the surface does not become re-contaminated or begin oxidizing.
• Fasteners: Fasteners, such as nuts, bolts and washers, are often overlooked during the preparation process. When cleaning an oil tank, ensure that fasteners receive proper attention so they don’t become the cause of premature coating failures.
• Edge preparation: Coatings have a tendency to pull back from sharp edges, leaving a thin layer that quickly breaks down. Techniques, such as grinding profiles into the edges of drainage holes and cutouts, will improve the coating’s adhesion and coverage. In general, the most effective profile is a rounded edge. Bear in mind that good surface preparation involves cleaning around cut edges. 

Instead of hoping that the weather works in their favor, proactive contractors rent temporary humidity control solutions, like those offered by Polygon, for an oil tank surface coating preparation. Such solutions allow you to establish, maintain and monitor ideal environmental conditions, regardless of the weather outside, so you can meet job specifications in any conditions. Polygon’s cost-effective solutions allow your team to work around the clock, enabling your firm to meet deadlines, save money and ensure a successful coating preparation and application.

[Photo from Rennett Stowe via CC License 2.0]