Steel Sheet, Metallic Coated and Polymer Precoated for Corrugated Steel Pipe

A742/A742M: Standard Specification for Steel Sheet, Metallic Coated and Polymer Precoated for Corrugated Steel Pipe

When specifying materials for critical infrastructure, ensuring durability and longevity is paramount. The ASTM A742/A742M standard provides engineers and designers with an essential framework for selecting and procuring high-performance steel sheet designed for corrugated steel pipe (CSP) applications. This authoritative specification ensures that the coated steel sheet meets stringent requirements for corrosion resistance and mechanical integrity, vital for the long-term performance of drainage systems and other civil engineering projects.

What is A742/A742M?

ASTM A742/A742M, "Standard Specification for Steel Sheet, Metallic Coated and Polymer Precoated for Corrugated Steel Pipe," establishes comprehensive material and performance requirements for polymer precoated steel sheet. Originating from ASTM International, this standard ensures that the steel sheet, featuring both a metallic coating (such as zinc or aluminum-zinc alloy) and a protective polymer layer, is suitable for the demanding conditions encountered in corrugated steel pipe manufacturing and use. Its primary purpose is to guarantee a consistent, high-quality material that offers superior protection against environmental degradation.

Scope & Purpose

This industry-leading standard governs the properties and performance of steel sheet intended for the fabrication of corrugated steel pipe. It specifically details requirements for the metallic coating type, the polymer coating composition, adhesion, impact resistance, thickness, and other critical performance characteristics. The scope encompasses steel sheet supplied flat or corrugated, in coils or cut lengths, with a mill-applied polymer coating on both sides. However, it does not cover the fabrication processes of the corrugated steel pipe itself, nor does it specify installation procedures.

Who Must Comply?

• • Primary audience: Materials Engineers, Quality Control Inspectors, Procurement Specialists, Production Managers, and Civil Engineers involved in the design, specification, manufacturing, or purchasing of corrugated steel pipe and its constituent materials.
• • Industries affected: Construction, Manufacturing, Civil Engineering, Transportation, and Infrastructure Development.
• • Compliance nature: Typically voluntary, but often mandated by project specifications, government regulations, or contractual agreements, making it practically essential for many applications.
• • Enforcement: Compliance is generally verified through material testing and certification by manufacturers, and often audited by project owners, specifying engineers, or third-party inspection agencies.

Key Requirements Overview

Professionals working with A742/A742M must ensure the following core aspects are addressed:

• • Metallic Coating: The standard requires conformity to specific ASTM standards for metallic coatings, such as zinc, 55% aluminum-zinc alloy, or zinc-5% aluminum-mischmetal alloy, as specified in the order.
• • Polymer Coating: The polymer coating must be composed of specified materials and applied to meet defined thickness grades, ensuring adequate protection.
• • Performance Properties: Key provisions include stringent requirements for coating adhesion, impact resistance, abrasion resistance, and freedom from holidays (pinholes or voids) to guarantee long-term durability.
• • Environmental Resistance: The specification mandates testing for freeze-thaw resistance and weatherability, ensuring the material can withstand typical environmental exposures without degradation.
• • Material Identification: Clear documentation and ordering information are required, specifying the ASTM designation, year of issue,