Added Longevity with Thermoplastic Polymer Coated Structural Steel Plate

Basic corrugated steel pipes were invented in 1896 and have since evolved into buried steel structures with the possibility of spans reaching upwards of 120 ft (40 m). To meet increasing design life requirements, galvanized and polymer laminate coatings have been developed to extend the life of the steel. In general, galvanized coatings perform well in hard water and non-abrasive conditions whereas polymer coatings perform well in these conditions plus salt-laden, soft water and moderately abrasive environments. To date, polymer laminate systems have been restricted to shallow corrugation profiles with maximum spans of approximately 12 ft (3.6 m), thus limiting greater spanned buried steel structures as a solution in less adverse environments. A new thermoplastic polymer system, comprised of a zinc rich primer and ethylene acrylic acid topcoat, has been developed. This paper introduces the new thermoplastic polymer system, comparing it to polymer laminated, galvanized and aluminized type 2 coatings. The coating has been used successfully since 2005 and recently completed a series of performance testing. Testing suggests the thermoplastic polymer coating meets, and in most cases exceeds, the performance of competing technologies. Discussion is focused on the laboratory tests, a recently developed performance guideline and field installations. Nearly 10 years of field experience, with over 20 structures designed and manufactured in Canada alone, support the laboratory results obtained and presented, enabling readers to gain an understanding of applications this new coating facilitates.