Choosing the right liner material for your secondary containment system is a critical decision that affects long-term performance, regulatory compliance, and total cost of ownership. This article provides a technical comparison of the two most widely used containment liner materials: polyurea coatings and PVC liners.
Material Properties Overview
Polyurea
Polyurea is a type of elastomer formed by the reaction of an isocyanate component and a resin blend component through step-growth polymerization. For containment applications, spray-applied polyurea coatings are applied directly to foam or substrate surfaces, creating a seamless, monolithic membrane.
Key properties:
- Shore A hardness: 85-95 (tunable)
- Tensile strength: 2,000-4,500 psi
- Elongation at break: 300-600%
- Temperature range: -60°F to 350°F
- Chemical resistance: Excellent to petroleum hydrocarbons, moderate to strong acids
- UV resistance: Good to excellent (with UV stabilizers)
PVC (Polyvinyl Chloride)
PVC liners for containment applications are typically reinforced fabric panels welded together at seams. They are available in thicknesses from 20 mil to 80 mil for containment applications.
Key properties:
- Tensile strength: 200-400 lb/in (depending on thickness)
- Temperature range: -10°F to 150°F (unreinforced)
- Chemical resistance: Good to petroleum hydrocarbons, poor to aromatic solvents
- UV resistance: Moderate (degrades significantly over 3-5 years without UV stabilizers)
Performance Comparison
Seam Integrity
Polyurea wins decisively. Spray-applied polyurea creates a seamless coating with no joints or seams. PVC liners require heat-welded seams at every panel junction, which are the primary failure points. In our field studies, over 80% of PVC liner failures occurred at seams.
Puncture Resistance
Polyurea is significantly more puncture-resistant. Standard containment polyurea resists puncture from typical job site debris (rocks, equipment feet) that routinely penetrate 40-mil PVC. For vehicle drive-over applications (foam berms), polyurea is the only viable choice.
Temperature Performance
Polyurea significantly outperforms PVC in both extreme cold and heat. PVC becomes brittle below 10°F and can crack under flex loading. Polyurea remains flexible at temperatures as low as -60°F, making it the only appropriate choice for Arctic and sub-Arctic applications.
Cost Comparison
PVC has lower upfront material costs ($0.40-$1.20/sq ft for 40-mil PVC vs. $3-8/sq ft for applied polyurea). However, when total lifecycle costs are considered over a 10-year period, polyurea typically proves more economical due to lower maintenance, repair, and replacement costs.
OCA Recommendation
For portable foam berm containment systems, drive-through containment areas, and cold-weather applications, OCA recommends polyurea-coated systems. For large-area liner applications with controlled environments and lower mechanical stress, properly installed PVC can be a cost-effective solution when budget constraints preclude polyurea.