Breakthroughs in 100% solids polyurethane coating technology have produced higher performing, non-flammable polyurethane coatings with 2000+ PSI adhesion to steel without primers and zero VOC’s. These coatings have produced environmentally friendly solutions to anti-corrosion tank protection while meeting the requirements of Underwriters Laboratories standards UL 1746 Part II and Part IV. They offer high physical properties and substantial performance, safety and environmental advantages over older systems and existing Fiberglass Reinforced Polyester (FRP) systems. The paper briefly reviews the history of underground steel tank anti-corrosion protection and discusses Underwriters Laboratories UL 1746, Part 1, Part II and Part IV standards. It highlights the newest standard, Underwriters Laboratories UL 1746, Part IV and the advantages of systems that meet this new standard.
Existing anti-corrosion coatings for underground steel tanks have many drawbacks. The high performance systems are environmentally unfriendly, hazardous to the applicator and the environment and contain carcinogens. In addition, due to the VOCS being released into the atmosphere and community objections, some manufacturing locations are having their production curtailed. The flammability of the existing system has resulted in fires that have destroyed manufacturing facilities as well. A better safer, faster and less polluting system with better performance is required by the industry.
The new generation of underground steel tank anti-corrosion coatings is 100% solids polyurethane. This reaction product of an isocyanate and a polyol plays a vital role in many industries and in our everyday lives.
Recent developments in polyurethane technology have resulted 100% solids, instant setting, two component, highly cross-linked polyurethane coatings for use as anti-corrosion coatings for underground steel tanks. The new 100% solids polyurethane offer higher performance and greater safety than older technologies all the while assuring maximum anticorrosion protection. The new 100% solids polyurethane anti-corrosion systems meet the most rigorous requirements of the Underwriters Laboratories UL standard, UL 1746, Part IV.
The new 100% solids polyurethanes are safer and more environmentally friendly than traditional anti-corrosion coatings. Also, because of the 100% solids polyurethane’ unique properties, they reduce the time necessary to apply the coatings. They can be applied regardless of ambient temperatures and dramatically reduce the overall time required to coat the tank.
In addition to these benefits, they meet the Underwriters Laboratories (UL) and Steel Tank Industry (STI) standards and specifications for underground steel tank anti-corrosion protection and have proven themselves over the years as excellent anti-corrosion coatings.
By definition, the term ‘100% solids’ means that the system does not use any solvent to dissolve, carry or reduce any of the coating resins. After reacting during application, the resins, which are normally in a liquid state, become a 100% solid film.
WHAT ISA POLYURETHANE?
Polyurethane is a very versatile thermoset plastic that was invented by Otto Bayer in the late 1930’s1. Polyurethane are created by reacting an isocyanate and a polyol (Figure 1). By carefully compounding various types of polyurethane designed for specific uses and applications can be produced.
