AASHTO M 274 is a highway-oriented material specification for aluminum-coated Type 2 steel sheet used to manufacture corrugated steel pipe. It is especially relevant to DOT drainage, culvert, storm-sewer, and underdrain projects where the contract documents call for Type 2 aluminum-coated steel. The current listed edition is M 274-87 (2025), while the standard remains identified by its original 1987 designation. 

For procurement, the important distinction is that M 274 specifies the aluminum-coated sheet material, not a universal finished-pipe dimension or a complete project design. Pipe diameter, corrugation, thickness, fabrication, laying length, joints, and installation requirements normally come from the project drawings, DOT specifications, and the applicable corrugated-pipe standard.

What AASHTO M 274 Covers

AASHTO M 274 is titled Steel Sheet, Aluminum-Coated (Type 2), for Corrugated Steel Pipe. Its scope covers steel sheet used to fabricate corrugated steel pipe for drainage pipe and underdrains. The aluminum coating is commercially pure aluminum, applied by the hot-dip process on continuous coating lines. The material can be supplied as coils, flat cut lengths, or corrugated cut lengths. 

The specification also addresses ordering information, general requirements, chemical composition, physical properties, dimensions and tolerances, sampling and testing, certification, and marking. Its referenced documents include AASHTO T 213M/T 213 for coating mass and ASTM A463/A463M for aluminum-coated steel sheet. 

AASHTO M 274 vs ASTM A929

M 274 and ASTM A929 are closely related specifications, but they should not be treated as identical documents. M 274 is an AASHTO highway specification specifically focused on Type 2 aluminum-coated sheet for corrugated steel pipe. ASTM A929/A929M is a broader metallic-coated sheet specification for corrugated steel pipe. The current A929/A929M-24 scope covers galvanized, 55% aluminum-zinc alloy-coated, and aluminum-coated Type 2 sheet. 

This relationship is important in highway procurement. A DOT may specify M 274 for the material while using another AASHTO or state-specific document to define the finished pipe. A current AASHTO standards listing, for example, separately identifies M 274 for Type 2 aluminum-coated sheet and M 36M/M 36 for metallic-coated corrugated steel pipe. 

Why M 274 Appears in Highway and DOT Projects

The standard is naturally suited to highway drainage because its stated scope is corrugated steel pipe used for drainage pipe and underdrains. In actual public works procurement, the material specification is normally embedded in a larger contract package containing drawings, roadway requirements, drainage calculations, structural criteria, installation instructions and inspection procedures.

Some municipal specifications explicitly recognize M 274 Type 2 aluminum-coated steel as an alternate or specified material for culverts and underdrains, illustrating how the standard can enter local highway and public-infrastructure procurement. 

Type 2 Aluminum Coating Requirements

M 274 defines Type 2 as commercially pure aluminum applied by hot-dip coating. Unlike a generic commercial description such as “aluminized steel,” the AASHTO designation gives the purchasing team a specific material route and coating class. 

The specification provides one coating-mass level rather than multiple coating classes. Coating mass is verified through the referenced AASHTO T 213M/T 213 method, while ASTM A754/A754M and ASTM E376 are also referenced for coating measurement and testing. 

Typical Highway Specification Chain

For a DOT project, a practical specification chain can look like this:

This approach prevents a common purchasing mistake: sending a supplier only “M 274 pipe” without giving the dimensional and fabrication information needed to manufacture the finished product.

What Specifications Should Be Included?

Long Pipe Sections vs Short Pipe Sections

Highway projects may require different laying lengths depending on transportation restrictions, installation equipment, site access, pipe diameter, trench conditions and the jointing system. A project should therefore specify whether the supplier is expected to provide long factory sections, shorter sections for easier handling, or a combination of standard laying lengths.

Longer sections can reduce the number of field joints, potentially simplifying installation. Shorter sections can be easier to load, transport and position on restricted sites. Neither approach is automatically better; the correct choice depends on the project's handling and installation plan.

Connections and Accessories

For a highway drainage project, the pipe body is only part of the delivery package. Coupling bands, bolts, fasteners, gaskets where specified, end treatments and other accessories should be identified in the project documents. The connection system must be compatible with the pipe geometry and the governing DOT specification.

Procurement should also clarify whether accessories are included in the pipe price or supplied as separate line items. This avoids a common delivery problem in which the pipe sections arrive on site but the required connection components have not been included.

Quality Documentation for DOT Delivery

Public infrastructure projects generally require stronger traceability than a standard commercial drainage order. The supplier should be prepared to provide the material and coating documentation required by the contract, including applicable certificates, dimensional inspection records, coating verification and shipment identification.

Because M 274 distinguishes the manufacturer of sheet, fabricator of pipe, and purchaser of finished pipe, this separation is useful when defining responsibilities for certificates and inspection. 

AASHTO M 274 in a DOT Bid: What Buyers Should Watch

When M 274 appears in a bid document, procurement managers should avoid treating it as the complete commercial description. First identify the exact DOT or agency specification. Then check whether the contract requires M 274 alone, M 274 together with a finished-pipe standard, or an approved-equivalent material.

Some project specifications may explicitly allow Type 2 aluminum-coated steel as an alternate to another corrugated-steel coating system. For example, a municipal construction specification identifies aluminum-coated Type 2 steel pipe as an equal alternate under specified conditions. 

The bid documents therefore control. A supplier should not substitute a different coating family simply because it appears technically similar.

Teda Ganghua Supply Support

Teda Ganghua can support procurement managers sourcing aluminum-coated steel materials for highway drainage, culvert and stormwater projects by coordinating coating requirements, steel thickness, pipe dimensions, fabrication details and inspection documentation. For DOT orders, providing the project specification and drawings helps align the material with the required delivery configuration.

For project-specific requirements, you can contact Teda Ganghua for aluminized steel supply support and confirm the appropriate material, processing and documentation route for the project.

FAQs

What is AASHTO M 274?

AASHTO M 274 is the specification for steel sheet, aluminum-coated Type 2, used to fabricate corrugated steel pipe for drainage pipe and underdrains. The Type 2 coating is commercially pure aluminum applied by the hot-dip process. 

Is M 274 a finished corrugated pipe standard?

Primarily, it is a material specification for the aluminum-coated sheet used to make corrugated steel pipe. Finished-pipe dimensions, fabrication, joints and installation requirements may be controlled by another AASHTO or DOT specification.

How is M 274 related to ASTM A929?

Both address aluminum-coated material for corrugated steel pipe, but M 274 is an AASHTO Type 2 specification focused on highway drainage applications, while ASTM A929/A929M is a broader metallic-coated sheet specification for corrugated steel pipe. 

What should a DOT buyer specify besides M 274?

The order should normally identify the applicable finished-pipe standard, diameter, corrugation profile, steel thickness, laying length, fabrication/seam configuration, connection system, inspection requirements and project-specific DOT provisions.

Does M 274 define pipe length?

M 274 primarily defines the coated sheet material. Pipe laying length and delivery configuration should be specified separately according to the project drawings, fabrication requirements, transportation limits and installation plan.