Introduction
Ground storage tanks are critical assets in water treatment, petroleum storage, chemical processing, and industrial manufacturing. Protecting these tanks with properly applied coatings and linings is essential for preventing corrosion, maintaining structural integrity, and ensuring regulatory compliance. However, tank painting and lining projects present unique challenges that can compromise results if not properly addressed.
In our experience at Markley's Precision Company, the challenges fall into three major categories: application issues, performance problems, and regulatory compliance. Understanding these challenges — and knowing how to solve them — is what separates a successful tank coating project from a costly failure.
Challenge 1: Application Issues
The application phase is where most tank coating problems originate. Even the best coating material will fail if it is applied incorrectly, in the wrong conditions, or on a poorly prepared surface.
Surface Preparation Failures
Industry data consistently shows that 60% to 80% of all coating failures are caused by inadequate surface preparation. For ground storage tanks, surface preparation challenges include:
- Residual contamination: Oil, grease, salts, and chemical residues on the tank surface prevent coating adhesion. These contaminants must be thoroughly removed before blasting, often requiring solvent cleaning or pressure washing.
- Insufficient blast profile: Coating adhesion depends on mechanical bonding to a properly profiled surface. If the surface profile is too shallow, the coating lacks the "tooth" it needs to grip. If it's too deep, the coating may not bridge the peaks and valleys, leaving thin spots vulnerable to corrosion.
- Flash rust: In humid environments, freshly blasted steel can begin rusting within minutes. If the coating is not applied before flash rust forms, adhesion is compromised from the start.
Solutions: Implement rigorous pre-blast cleaning protocols, verify surface profile with replica tape or profile gauges, and monitor environmental conditions (temperature, humidity, dew point) continuously. Apply coatings within the specified time window after blasting to prevent flash rust.
Weather and Environmental Conditions
Ground storage tanks are typically coated outdoors, making the project dependent on weather conditions. Key environmental challenges include:
- Temperature extremes: Most coatings have minimum and maximum application temperatures (typically 50°F to 100°F). Applying outside this range causes improper cure, reduced adhesion, and film defects.
- Humidity and dew point: Coating application requires that the substrate temperature remain at least 5°F above the dew point. High humidity conditions can trap moisture in the coating film, causing blistering and adhesion failure.
- Wind: High winds create dry spray conditions where coating droplets partially dry before reaching the surface, resulting in a rough, porous film with reduced protection.
- Rain: Any moisture on the surface during application will cause immediate adhesion failure. Weather delays are one of the largest schedule risks in tank coating projects.
Solutions: Build weather contingency into project schedules, use environmental monitoring equipment throughout the application process, and consider temporary enclosures or wind screens for critical applications. Schedule work during optimal seasonal windows when possible.
Access and Logistics
Ground storage tanks present significant access challenges. Interior work requires confined space entry procedures, and exterior work on large tanks requires scaffolding, man-lifts, or rope access. The logistics of getting equipment, materials, and personnel to the work surfaces efficiently and safely adds complexity and cost to every project.
Solutions: Develop a detailed access plan before the project begins, ensure all access equipment meets OSHA requirements, and coordinate access schedules to minimize crew idle time. Pre-stage materials and equipment to reduce setup and transition time.
Challenge 2: Performance Problems
Even when a coating is properly applied, performance issues can develop if the wrong system was specified or if the coating is exposed to conditions beyond its design parameters.
Adhesion Failure
Adhesion failure — where the coating delaminates from the substrate — is the most common performance problem in tank coatings. Causes include:
- Contamination beneath the coating that was not removed during surface preparation
- Exceeding the recoat window between coats, preventing intercoat adhesion
- Applying over moisture or flash rust
- Incompatibility between the coating system and the substrate or previous coating
Solutions: Conduct adhesion testing (per ASTM D4541) during and after application, follow manufacturer recoat windows strictly, and verify substrate compatibility before specifying the coating system.
Corrosion Under Coating
When pinholes, holidays, or thin spots exist in the coating film, moisture and corrosive agents reach the substrate and begin corroding from underneath. This undercutting corrosion can spread laterally beneath apparently intact coating, causing large-scale failure.
Solutions: Perform holiday (spark) testing on 100% of coated surfaces to detect pinholes and voids. Apply stripe coats to edges, welds, corners, and fasteners where coating tends to thin. Maintain specified dry film thickness across all surfaces.
Chemical Resistance Failure
Selecting a coating with inadequate chemical resistance for the service environment leads to softening, swelling, blistering, or dissolution of the coating film. This is particularly common in chemical storage and wastewater applications where exposure conditions are aggressive.
Solutions: Perform thorough chemical exposure analysis before selecting the coating system. Consult manufacturer chemical resistance guides and, when in doubt, request immersion testing with actual service chemicals. Specify coatings with proven performance in the specific exposure environment.
Challenge 3: Regulatory Compliance
Tank painting and lining projects are subject to a complex web of federal, state, and local regulations that can create significant challenges for project planning and execution.
EPA Regulations
The EPA regulates tank coatings through several programs:
- Volatile Organic Compound (VOC) limits: EPA and state air quality regulations limit the VOC content of coatings. Many high-performance industrial coatings must be reformulated to meet these limits, sometimes at the expense of performance characteristics.
- SPCC (Spill Prevention, Control, and Countermeasure) plans: Petroleum storage tanks must comply with SPCC regulations, which include requirements for tank integrity and secondary containment. Coating maintenance is an integral part of SPCC compliance.
- Lead and hazardous materials: Removing old coatings from tanks built before the 1980s often involves lead-containing paint. EPA regulations under RCRA require proper containment, removal, and disposal of lead-based coatings.
OSHA Requirements
Worker safety regulations significantly impact tank coating operations:
- Confined space entry: Interior tank work requires compliance with OSHA 29 CFR 1910.146, including entry permits, atmospheric monitoring, attendant personnel, and rescue provisions.
- Fall protection: Exterior work on tanks requires fall protection systems compliant with OSHA 29 CFR 1926 Subpart M.
- Respiratory protection: Abrasive blasting and coating application generate airborne particulates and solvent vapors that require respiratory protection programs per OSHA 29 CFR 1910.134.
- Hazard communication: All coating materials must have current safety data sheets (SDS), and workers must be trained on the hazards of the materials they handle.
VOC Compliance
VOC regulations vary by state and even by county, creating a patchwork of compliance requirements that project teams must navigate. Some areas have adopted California's South Coast Air Quality Management District (SCAQMD) Rule 1113 limits, which are among the strictest in the nation. Using compliant coatings that still meet performance requirements requires careful product selection and, in some cases, alternative application methods.
Solutions: Engage regulatory specialists early in the project planning process. Verify VOC limits for the specific project location. Select coatings that meet both performance and regulatory requirements. Ensure all confined space, fall protection, and respiratory protection programs are in place before work begins.
Why MPC Succeeds Where Others Struggle
At Markley's Precision Company, we have built our reputation on successfully navigating these three challenges on every project we undertake. Our crews are trained in proper surface preparation techniques, our project managers monitor environmental conditions in real time, and our quality control program catches defects before they become failures. We stay current on EPA, OSHA, and state regulations so our clients can be confident their projects are fully compliant.
If you're facing a ground storage tank painting or lining project and want a contractor who understands the challenges and knows how to overcome them, contact Markley's Precision Company today.