AS/NZS 1163 C350 pipe is a cold formed structural steel hollow section built to the joint Australian and New Zealand specification AS/NZS 1163. The mark “C350” guarantees 350 MPa minimum yield strength and 430 MPa minimum tensile strength. Repeatedly I’ve seen this grade specified on commercial building frames, bridge support members and industrial trusses because it offers the right balance of load-bearing capacity, manageable weight and cost control, which is why it is the most widely adopted grade within the AS/NZS 1163 family of structural steel grades for medium-to-high-load applications.
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Understanding AS/NZS 1163 C350 Pipe Specifications and Standards
Mechanical and Chemical Properties
C350 cold-deformed hollow sections, yield strength not less than 350 MPa, tensile strength 430-600 MPa. Elongation normally reaches 16-22%, depending on the thickness of the wall. This allows field bending and welding connections with no pre-heat for most common thicknesses. The carbon percentage is limited to 0.20% and the manganese content to 1.60% so that the CE may be maintained low for convenient on-site welding.
Dimensional Tolerances and Size Range
The standard covers circular, square or rectangular hollow portions. The allowances for outside diameter and wall thickness are given in Table 7 of AS/NZS 1163. The structure performance is protected by out of roundness limitations.
Manufacturing Process and Certifications
Most C350 pipe is produced by the mill as Electric Resistance Welded (ERW) or High Frequency Welded (HFW) tube. The outside diameters are in the range of 21.3 mm to 508 mm and the wall thicknesses are in the range of 1.6 mm to 16 mm. AS/NZS 1163 certification is a third party requirement only and purchasing teams should always request a Mill Test Certificate (MTC) to EN 10204 Type 3.1 or 3.2 including actual heat analysis and mechanical test findings for AS/NZS 1163 C350 pipe. The L0 version (C350L0) adds Charpy V-notch impact testing at 0°C when the temperature is low or the load is changing.
Applications of AS/NZS 1163 C350 Pipes in Structural Engineering
These strengths make the C350 the best choice when the C250 can't handle the load anymore and the C450 would over-engineer the frame and make it more expensive.
- Column construction: C350 circle and square hollow sections (CHS/SHS) are designated as major columns in commercial structures, as their closed cross-section resists buckling more effectively than open sections of comparable weight. A mid-rise office frame in a Sydney CBD project using 200×200×6 SHS C350 columns reduced the steel tonnage by about 12% compared to a C250 design.
- Roof trusses and purlins: The increased yield strength allows for lighter chord and web members in long span roof trusses which decreases dead load on the primary frame. C350 RHS are often specified for top and bottom chord members in industrial warehouses and airport canopies in Australia and New Zealand.
- Bridge and infrastructure frameworks: Auxiliary bridge members, conveyor galleries and pipe racks in mining and port operations rely on C350 cyclic loading resistance. Low CE values are in line with the requirements for full penetration butt welds in AS/NZS 1554 welding procedures.
These application strengths make C350 the go-to choice when C250 no longer meets load requirements but C450 would over-engineer the structure and inflate cost.
Comparing AS/NZS 1163 C350 Pipe with Alternative Standards and Materials
C350 vs. C250
C250, with a minimum yield strength of 250 MPa, 40% less than C350. C250 is appropriate for parts that don’t have to carry considerable weight, such screens or stairs. For increasing span lengths, column heights or total axial and bending loads, the engineer can opt for a smaller section with C350, saving weight and money. And the price difference between C350 and C250 is not that big normally, and the smaller section size usually makes up for it.
C350 vs. C450
says, The higher strength is useful for earthquake protection or short poles that handle a lot of weight, but the higher CE value implies thicker welds need to be heated first, which takes longer and costs more to create. I frequently see C350 utilised when the AS 4100 design tests allow it, because manufacturers appreciate the easier welding procedure and cheaper material.
C350 vs. ASTM A500 Grade C
C350 has a minimum yield of 350 MPa. AS/NZS 1163 C350 pipe has a minimum yield of 350 MPa. Astm A500 Grade C has a minimum yield of 46 ksi (317 MPa). In Australia and New Zealand, building owners and authorising professionals ensure projects fulfil the National Construction Code (NCC) by complying with AS/NZS 1163. Inspection non-conformance may occur when using ASTM parts instead of an approved version. Cross-standard replacement should always be considered only after reviewing the applicable code requirement.
Procurement Guide for AS/NZS 1163 C350 Pipes
There are several steps that need to be taken carefully in order to find certified structural hollow sections in international supply chains. Here are the main things that make a buying project successful:
- Supplier certification: Ensure supplier has current AS/NZS 1163 product certification and can supply third-party MTC reports for each batch sent. Reliable batch to batch consistency requires at least an ISO 9001-registered quality manage- ment system.
- Lead time and inventory depth: For most medium sized building projects, procurement cycles are 3-6 weeks. If the supplier has a lot of stock in his warehouse or if he can commit to 15 to 30 days of production and shipping then the risk to the schedule is dramatically reduced. Confirm available stock sizes before placing a purchase order.
- Customisation and value-added services: Cut to length, end facing, hot dip galvanising and anti-corrosion coatings such as FBE or 3LPE enhance pipe service life and reduce site effort. Having one supplier supplying various services under one roof cuts down on the supply chain and the documentation becomes easier.
- Documentation package: For import and project handover you require Inspection and Test Plan (ITP), Manufacturing Procedure Specification (MPS), MTC and packing list. Engineering contractors and owners engineers regularly request this whole document set at goods receipt.
Checking these points early on in the shortlisting process protects the project plan and the structure, and it lowers the chance of having to make expensive changes during building.
Quality Assurance and Testing of AS/NZS 1163 C350 Pipes
Key Testing Protocols
Standard tests are tensile tests to determine yield and tensile strength, Charpy V-notch impact tests for L0 grades, chemical heat analysis and measurement of the dimensions against the ranges in Table 7. The non-destructive testing (NDT) of the longitudinal weld seam is performed by means of 100% Eddy Current or ultrasonic technologies, detecting faults inside the pipe prior to leaving the mill.
Reading the MTC Correctly
The MTC needs to provide test findings, not merely say “meets specification”. Check that the heat number on the certificate matches the stencil mark on the pipe. Check that yield strength, tensile strength, elongation and chemical composition are to the AS/NZS 1163 C350 requirements. The MTC for EN 10204 type 3.1 is signed by the inspector on behalf of the manufacturer. Type 3.2 – Witness, Independent third party.
On-Site Inspection Best Practices
In the field, employ ultrasonic thickness gauges to assess the wall thickness at many spots along the length of the wall. The weld seams are to be visually checked by the shop for slivers, seams or pitting which could impair the quality of the weld or the adhesion of the galvanising during fabrication. Before installation, store pipes on level, above-ground platforms to prevent surface rust. These steps ensure structural integrity from conveyance to the final link.
Conclusion
C350 cold-formed hollow sections are ideal for commercial building frames, industrial trusses and bridge support structures. Strong, easy to assemble and the right size every time. The best method to maintain the project on schedule and within the standards is to select a supplier with full AS/NZS 1163 certification, who provides batch MTC reports and holds adequate stock of AS/NZS 1163 C350 pipe. When the structure grade, the documentation and the delivery date come together, the buying procedure moves easily from technical selection to on-site installation.
FAQ
What is the minimum yield strength of AS/NZS 1163 C350 pipe?
The minimum yield strength is 350 MPa, with a tensile strength range of 430–600 MPa. These values are confirmed through tensile testing on each production batch and reported in the MTC.
When should I choose C350L0 instead of standard C350?
Select C350L0 when the structure will experience temperatures at or below 0°C, or when the design involves dynamic or impact loading. The L0 suffix indicates guaranteed Charpy V-notch impact energy absorption at 0°C.
Does C350 pipe require pre-heating before welding?
For standard wall thicknesses and a low CE value (Carbon ≤ 0.20%), pre-heating is generally not required under AS/NZS 1554 welding procedures. Thicker sections or high-restraint joints may need preheat — always consult the welding engineer.
How does bulk order volume affect C350 pipe pricing?
Larger order quantities typically attract volume discounts and lower per-unit freight costs. Suppliers with deep stock can often offer better pricing on standard sizes. Confirm MOQ and price breaks during the inquiry stage.
What documents should I request with each C350 shipment?
Request the MTC (EN 10204 Type 3.1 or 3.2), ITP, MPS, dimensional inspection report, NDT report, and packing list. These documents are required for project handover and regulatory compliance in Australia, New Zealand, and most Middle East projects.
Request a Quote from Longma Group — Certified AS/NZS 1163 C350 Pipe Supplier
Since 2003, Longma Group has been making ERW and LSAW steel pipes and sending them to more than 90 countries. They are fully certified by AS/NZS 1163 and registered with ISO 9001. They get their raw materials from mills like Bao Steel and HBIS. As a direct manufacturer of AS/NZS 1163 C350 pipes, we offer full MTC documentation, delivery guaranties of 15 to 30 days, and technical support in English. To get a quote on your job, please email our team at info@longma-group.com or visit our website at longma-group.com.
