Overview of AS/NZS 1163
AS/NZS 1163 is the joint Australian and New Zealand Standard titled "Cold-formed structural steel hollow sections". It specifies the requirements for the manufacture of circular, square, and rectangular hollow sections (CHS, SHS, RHS) made from carbon steel, primarily used in structural applications.
The key takeaway is that these sections are cold-formed. This means the steel strip is formed into a hollow section at ambient (room) temperature, which results in different mechanical properties compared to hot-formed or seamless pipes.
Key Points of the Standard
1. Scope and Application
What it covers: Welded circular, square, and rectangular hollow sections (CHS, SHS, RHS) manufactured from steel strip that has been cold-formed.
Primary Use: Structural applications in buildings, bridges, and other engineering structures. It is also widely used for mechanical purposes, handrails, and support frames.
What it does NOT cover: Seamless pipes (covered by AS 1074 or AS 1548) or hot-formed hollow sections (covered by AS/NZS 1074).
2. Grades of Steel
The standard defines several grades based on their minimum yield strength. The most common grades are:
C250: Minimum yield strength of 250 MPa. This is a general-purpose grade.
C350: Minimum yield strength of 350 MPa. This is a high-strength grade, very common for structural members where weight saving is important.
C450: Minimum yield strength of 450 MPa. Used for high-stress applications.
The "C" stands for "Cold-formed".
3. Manufacturing Process
Forming: Steel strip (coil) is progressively cold-formed into a circular, square, or rectangular shape.
Welding: The edges are welded together using either:
HFIW (High-Frequency Induction Welding): The most common method.
SAW (Submerged Arc Welding): Typically used for thicker walls or larger diameters.
Sizing & Finishing: The welded tube is then sized to its final dimensions, and may be heat-treated, straightened, and cut to length.
4. Chemical Composition
The standard specifies maximum limits for elements like Carbon (C), Phosphorus (P), and Sulfur (S) to ensure weldability and ductility. The exact composition varies by grade and manufacturing route.
5. Mechanical Properties
This is the core of the standard, ensuring the material performs as expected.
Tensile Strength: The maximum stress the steel can withstand while being stretched.
Yield Strength (Rp0.2): The stress at which the material begins to deform plastically. This is a critical value for structural design.
Elongation: A measure of ductility, indicating how much the steel can stretch before breaking.
6. Dimensional Tolerances
AS/NZS 1163 provides strict limits on:
Outside Dimensions (O.D.): Tolerances for diameter (CHS) and width/depth (SHS/RHS).
Wall Thickness: Tolerances for the nominal wall.
Length: Tolerances for supplied lengths.
Straightness: Maximum allowable deviation from a straight line.
7. Testing and Certification
Manufacturers must perform tests to verify compliance, including:
Tensile tests
Flattening tests (for CHS) or reverse bend tests (for SHS/RHS) to check weld integrity.
Dimensional checks.
Material supplied to AS/NZS 1163 should come with a Test Certificate (usually a Type 3.1 Inspection Certificate per AS 1020) confirming it meets all requirements.
Comparison with Other Common Pipe Standards
It's important not to confuse AS/NZS 1163 with other common pipe standards.
| Feature | AS/NZS 1163 | AS 1074 (Pipe for Pressure Applications) | AS/NZS 3678 (Structural Steel - Plates & Sections) |
|---|---|---|---|
| Full Title | Cold-formed structural steel hollow sections | Steel pipes and tubulars for ordinary service | Structural steel - Hot-rolled plates, floorplate and sections |
| Primary Use | Structural (frames, supports) | Pressure & Piping (water, gas) | Structural (beams, columns, plates) |
| Forming | Cold-formed & Welded | Can be hot-formed, cold-formed, or seamless | Hot-rolled |
| Common Grades | C250, C350, C450 | C250, C350 (but to different specs) | 250, 300, 350 (e.g., GR250, GR350) |
| Key Focus | Strength, dimensional tolerances, weld ductility | Pressure-containing capability, hydrostatic testing | General structural properties, weldability |
Common Applications
Building Structures: Roof trusses, columns, purlins, and rafters.
Architectural & Construction: Handrails, balustrades, security screens, and scaffolding (specific designs).
Industrial: Machine frames, support structures, conveyor systems.
Agricultural: Sheds, cattle rails, equipment frames.
Furniture & Fit-outs: Modern furniture, shop fittings, display units.
Summary
AS/NZS 1163 is the go-to standard for cold-formed carbon steel hollow sections (CHS, SHS, RHS) used in structural and mechanical applications across Australia and New Zealand. When you specify a material to this standard, you are assured of a product with defined strength, ductility, and precise dimensions, making it reliable and predictable for engineers and fabricators.
Always ensure you receive the appropriate test certificates from your supplier to verify compliance for critical applications.
