Structural design drawings are the blueprint for project success-incorrectly specifying materials can lead to wrong steel deliveries, rework, and compliance issues. For engineers and designers using ASTM A871 Grade 60 Corten Steel, a key question arises: How do you clearly, accurately specify this grade in your drawings to ensure suppliers deliver the right material? The process is straightforward, but attention to key details ensures no misinterpretation, keeping your project on track.
Key Elements to Include in Your Specification
To avoid ambiguity, your design drawings must include these four critical, ASTM-aligned details-they form the foundation of a clear specification:
Full ASTM Grade Designation: Always specify "ASTM A871/A871M Grade 60" (include the "M" for metric compatibility). Never use vague terms like "Corten Steel" alone-this can lead to substitution with lower-grade weathering steels.
Mechanical Properties (Critical for Compliance): Note the minimum yield strength: 415 MPa (60 ksi) and tensile strength range: 485–620 MPa (70–90 ksi). This ensures the steel meets structural load requirements per ASTM standards.
Material Form & Thickness: Clearly state the form (e.g., "plate for tubular fabrication," "structural shapes") and thickness range (e.g., 6–100mm). For tubular structures, add "suitable for cold forming into seamless tubes" to align with fabrication needs.
Surface & Delivery Requirements: Specify "unpainted, as-rolled surface" (for Corten Steel's patina formation) and "Mill Test Report (MTR) required" to verify compliance. Add "fine-grain practice" if needed for cold-climate projects.
Step-by-Step Specification Guide
Follow this simple, practical process to add the specification to your drawings:
Add a "Materials" section in your drawing notes, clearly labeling the relevant structural components (e.g., "utility pole tubes, ASTM A871/A871M Grade 60 Corten Steel").
List the key properties: Yield Strength ≥415 MPa (60 ksi), Tensile Strength 485–620 MPa, fine-grain practice (per ASTM A871).
Specify fabrication compatibility: "Suitable for cold forming and welding per ASTM A6/A6M guidelines."
Include quality control: "Supplier to provide MTR confirming compliance with ASTM A871/A871M Grade 60 requirements."
Common Specification Mistakes to Avoid
These simple errors can cause costly delays-steer clear of them:
Skipping the full ASTM designation (e.g., writing "A871 Grade 60" without "ASTM A871/A871M").
Omitting mechanical properties-suppliers need clear strength requirements to deliver the right steel.
Vague surface requirements (e.g., not specifying "unpainted")-this may lead to coated steel that blocks patina formation.
In short, specifying ASTM A871 Grade 60 in design drawings comes down to clarity and attention to ASTM details. By including the full grade designation, key properties, material form, and quality requirements, you ensure suppliers deliver the correct Corten Steel-avoiding rework and keeping your project compliant and on schedule.
