Results of Testing of Polymer Precoated Steel Sheet According to ASTM A742
a report by KTA Tator
Just about 50 years ago, the first coil of plain galvanized steel was laminated with a polymer coating to improve the performance of corrugated steel pipe and allow for use in more aggressive environments. Providing even greater resiliency to the most sustainable product on the market, steel. This report describes the testing that was conducted on eight coating systems of various zinc weights and polymer coating thickness in comparison to the Requirements for Polymer Coating (Section 7) of ASTM A742/A742M, Standard Specification for Steel Sheet, Metallic Coated and Polymer Precoated for Corrugated Steel Pipe . The testing on each system included adhesion, impact, abrasion, chemical imperviousness, freeze thaw resistance and weatherability. A summary of the testing is contained in Table 1 of the report.
The systems included zinc weights of G90, G165 and G200 while there were two different polymer coating thicknesses compared – 10 mil vs 5 mil. Two different sample preparation methods were used in the creation of the sample sets. Two of the sample sets were cut from a full production run and lamination of a coil. While the other six sample sets were laminated using a micro-laminating process which simulates large production on individual coupon sized samples.
Overall, the results of the testing show good performance by each of the systems for weatherability, abrasion, imperviousness, and impact. As expected, the method of sample preparation did influence the systems performance on the adhesion test, where the full production samples met the requirement while all but one of the others had one replicate show disbonding. Additionally, the two systems prepared under full production had the best performance under freeze-thaw resistance testing.
To conclude, the results of the testing indicate that when reducing the zinc weight and polymer laminate thickness each by nearly half the system will still meet the requirements set forth in ASTM A742/A742M, Standard Specification for Steel Sheet, Metallic Coated and Polymer Precoated for Corrugated Steel Pipe.