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CSA S807-10 (2015): General Requirements for Carbon Steel and High-Strength Low-Alloy Steel Hollow Structural Sections
A comprehensive technical guide to the Canadian standard for hollow structural sections
CSA S807-10 (2015) is a key Canadian standard that establishes the general technical requirements for carbon steel and high-strength low-alloy (HSLA) steel hollow structural sections (HSS). Published by the Canadian Standards Association (CSA Group) and reaffirmed in 2015, this standard covers round, square, and rectangular HSS used primarily in structural and architectural applications. Adherence to CSA S807 ensures that HSS products meet consistent quality, safety, and performance levels across Canada, facilitating their acceptance in building codes and engineering designs.
Scope and Application
The standard applies to HSS manufactured by electric-resistance welding (ERW), submerged arc welding (SAW), or seamless processes. It covers three product categories based on the manufacturing method and intended use:
- Category H – Hot-formed or cold-formed and subsequently heat-treated HSS intended for structural applications where enhanced mechanical properties are required.
- Category T – Cold-formed HSS typical for general engineering and structural purposes.
- Category F – Fusion-welded HSS (SAW) used for large-diameter or non-standard sections.
Tip: Designers should verify that the specified category (H, T, or F) matches the structural application and any additional requirements in the governing building code, such as the National Building Code of Canada.
The standard outlines requirements for material composition, mechanical properties, dimensional tolerances, manufacturing practices, testing, marking, and certification. It references companion standards like CSA G40.20/G40.21 for steel grades and ASTM A500 for comparability with U.S. specifications.
Technical Specifications
Material Grades and Chemical Composition
CSA S807-10 (2015) prescribes chemical composition limits for the steel base metal and weld seam. The maximum allowable percentages are tightly controlled to ensure weldability and consistent mechanical performance. Typical limits include carbon ≤ 0.23%, manganese ≤ 1.40%, phosphorus ≤ 0.030%, and sulfur ≤ 0.030% for standard grades. Microalloying elements such as niobium, vanadium, and titanium may be added to meet strength requirements.
Mechanical Properties
The standard specifies minimum yield strength, tensile strength, and elongation for each grade and category. The table below summarizes the requirements for the most common HSS grades (comparable to CSA G40.21 grades):
| Grade Designation | Yield Strength (MPa) | Tensile Strength (MPa) | Minimum Elongation in 50 mm (%) |
|---|---|---|---|
| 350 (H/T/F) | 350 | 450 | 21 |
| 480 (H/T) | 480 | 550 | 18 |
| 550 (H only) | 550 | 620 | 15 |
For categories and shapes not listed, the standard provides rules for deriving equivalent requirements.
Dimensional Tolerances
CSA S807 sets strict tolerances on outside dimensions, wall thickness, straightness, twist, and corner radii. Key tolerances include:
- Outside dimensions (width, height, diameter): ±1% or ±0.5 mm, whichever is greater.
- Wall thickness: ±10% for t ≤ 10 mm; ±8% for t > 10 mm.
- Straightness: Maximum deviation of 0.15% of the length.
- Twist: Maximum of 0.5% of the larger side dimension per metre.
- Corner radii (square/rectangular): Minimum of 2 times the wall thickness.
Important: Dimensional tolerances are critical for fit-up in connections and must be carefully verified by fabricators, especially for large-scale projects or bolted connections.
Implementation Highlights
Successful implementation of CSA S807-10 (2015) involves several key production and quality control steps:
- Manufacturing: Forming and welding processes must be qualified. Heat treatment (normalizing or stress relieving) is required when specified by the purchaser or when needed to achieve Category H properties.
- Surface Condition: HSS must be free of cracks, laps, and other injurious defects. Minor surface imperfections are acceptable within defined limits.
- Testing: Tensile tests on the base metal and welded seam are mandatory for each heat or lot. Bend tests (guided and free bend) and hydrostatic tests may be required depending on the category.
- Non‑destructive Testing (NDT): For Category H and when specified, ultrasonic (UT) or electromagnetic inspection of the weld zone is performed to ensure seam integrity.
Best Practice: Fabricators should request a copy of the mill’s quality control manual and recent test certificates to verify that supplied HSS fully complies with CSA S807 requirements before fabrication begins.
The standard also mandates heat‑traceability: each section must be marked with the manufacturer’s name, the standard number (CSA S807), grade, category, dimensions, and heat identification. This allows full traceability back to the chemical and mechanical test records.
Compliance and Certification
Compliance with CSA S807 is typically verified through:
- Mill Test Certificates (MTCs): Producers must supply documentation certifying that the material meets all applicable requirements of the standard.
- Third‑Party Inspection: Projects that require compliance with CSA S16 (steel structures) or CAN/CSA A660 (certification of steel structures) often stipulate that HSS come from mills listed by an accredited certification body.
- Periodic Re‑evaluation: The 2015 reaffirmation confirms that the standard remains current. Regular audits by agencies such as the SCC (Standards Council of Canada) or ISO provide ongoing confidence in product quality.
Risk: Using HSS that does not comply with CSA S807 can lead to rejection during structural inspections, project delays, and potential liability issues. Always request up‑to‑date certificates and verify markings on delivered material.
For international projects, CSA S807 is often compared with ASTM A500 or EN 10210/10219. While the requirements are generally consistent, differences in tolerances, impact testing, and grading may require project‑specific substitution evaluations.
Frequently Asked Questions
Q: What is the difference between CSA S807 and ASTM A500 for HSS?
A: Both standards cover carbon steel HSS, but CSA S807 includes three categories (H, T, F) and supports higher‑strength grades (e.g., 480 and 550) with more stringent weld‑seam testing and heat‑treatment requirements. ASTM A500 has fewer grade options and different impact test rules. CSA S807 is the preferred standard in Canada for structural applications because it aligns with the National Building Code of Canada and companion standards such as CSA G40.20/G40.21.
A: Both standards cover carbon steel HSS, but CSA S807 includes three categories (H, T, F) and supports higher‑strength grades (e.g., 480 and 550) with more stringent weld‑seam testing and heat‑treatment requirements. ASTM A500 has fewer grade options and different impact test rules. CSA S807 is the preferred standard in Canada for structural applications because it aligns with the National Building Code of Canada and companion standards such as CSA G40.20/G40.21.
Q: Are there separate marking requirements for different categories of HSS?
A: Yes. Each HSS must be clearly marked with the category (H, T, or F) along with the grade, dimensions, and heat number. Category H sections also require the letters “NPS” (normalized) or “QT” (quenched and tempered) if heat‑treated. This helps fabricators and inspectors quickly identify the product’s capabilities.
A: Yes. Each HSS must be clearly marked with the category (H, T, or F) along with the grade, dimensions, and heat number. Category H sections also require the letters “NPS” (normalized) or “QT” (quenched and tempered) if heat‑treated. This helps fabricators and inspectors quickly identify the product’s capabilities.
Q: What is the significance of the 2015 reaffirmation?
A: The 2015 reaffirmation indicates that the CSA technical committee reviewed the 2010 edition and found it still relevant and technically sound. No substantive changes were made, but the reaffirmation confirms that the standard continues to reflect current best practices in the Canadian steel industry.
A: The 2015 reaffirmation indicates that the CSA technical committee reviewed the 2010 edition and found it still relevant and technically sound. No substantive changes were made, but the reaffirmation confirms that the standard continues to reflect current best practices in the Canadian steel industry.