ASTM A762 Standard specification covers polymer precoated corrugated steel pipe for use for water drainage, underdrains, the construction of culverts, and similar uses. The steel sheet used in fabrication of the pipe has a polymer protective coating over a metallic coating of zinc, aluminum-zinc alloy, or zinc-aluminum-mischmetal alloy. The corrugated steel pipe covered is classified as Type I, Type IA, Type IR, Type II, Type IIA, Type HR, Type III, and Type IIIA. Zn-Al-MM alloy coated materials are available in two coating classes, Class A and Class B. Pipes shall be formed from polymer precoated sheets. Pipe arch and coupling band dimensions shall conform the requirements of this specification.
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1.1 This specification covers polymer precoated corrugated steel pipe intended for use for storm water drainage, underdrains, the construction of culverts, and similar uses. Pipe covered by this specification is not normally used for the conveyance of sanitary or industrial wastes. The steel sheet used in fabrication of the pipe has a polymer protective coating over a metallic coating of zinc, 55 % aluminum-zinc alloy, or zinc-5 % aluminum-mischmetal alloy.
1.2 The polymer precoating provides extra protection of the base metal against corrosion or abrasion, or both, in addition to that provided by the metallic coating. Some severe environments may cause corrosion problems to accessory items such as rivets or coupling band hardware that does not have a polymer coating. Additional protection for polymer precoated corrugated steel pipe can be provided by use of coatings applied after fabrication of the pipe as described in Specification A 849.
1.3 This specification does not include requirements for bedding, backfill, or the relationship between earth cover load and sheet thickness of the pipe. Experience has shown that the successful performance of this product depends upon the proper selection of sheet thickness, type of bedding and backfill, controlled manufacture in the plant, and care in the installation. The installation procedure is described in Practice A 798.
1.4 This specification is applicable to orders in either inch-pound units as A 762, or in SI units as A 762M. Inch-pound units and SI units are not necessarily equivalent. SI units are shown in brackets in the text for clarity, but they are the applicable values when the material is ordered to A 762M.