ASTM A 742/A 742M

This specification covers polymer precoated steel sheet for corrugated steel pipe (CSP) which is coated after metallic coating on continuous lines by coil coating (roller coating or laminating) processes. The metallic coating shall either be zinc, aluminum-zinc alloy, or zinc-aluminum-mischmetal alloy. Sheet for this purpose shall be furnished flat in coils, flat in cut lengths, or corrugated in cut lengths, all being protected by a mill-applied polymer coating on both sides. The polymer coating shall be classified by grade corresponding to the thickness on each side. Requirements for the cleaning process of the steel sheet and for the polymer coating are given. The test methods for the following polymer coating properties are detailed: adhesion, impact, thickness, holidays, abrasion resistance, imperviousness, freeze-thaw resistance, weatherability, and resistance to microbial attack.