ASTM A500 Carbon steel square tube 50x50x3mm Grade B Cold Formed Welded Structural Section

At 50 x 50 x 3 mm this is the workhorse size of structural hollow section, and the one we ship most of. It is cold formed from hot rolled coil, welded along the corner, and then sized through Turks heads so that the flats stay flat and the corners keep a defined radius. Weight is 4.43 kg per metre, which makes a 6 m length about 27 kg, still light enough for two men to handle on site without a lift.

ASTM A500 Grade B is the specification most structural engineers outside Europe name for hollow sections, because it carries a defined minimum yield of 317 MPa and a tensile range of 400 to 550 MPa that can be used directly in allowable stress and LRFD calculations. We issue the mill test report with the heat number traceable to each bundle, which is what an inspector asks for before accepting the steel on a job.

• Defined Structural Values: Grade B gives 317 MPa minimum yield and 400 MPa minimum tensile, with elongation of 23 percent in 50 mm, so the section can be used in design calculations.
• Flat Flats and Defined Corners: Sizing passes keep flatness within 1 mm over the 50 mm face and corner radius at twice the wall, so bolted connections seat without shimming.
• Cold Formed Strength Gain: Cold forming raises the corner yield strength above the flat values, which is recognised in A500 and can be used for connection design.
• Heavy Enough to Thread: At 3 mm wall, the tube accepts an M8 or M10 tapped hole with enough thread engagement for handrail and bracket fixings.
• Weldable Without Preheat: Carbon equivalent stays under 0.35 for this chemistry, so MIG and TIG joints can be made in the field without preheating.
• Traceable Heat Numbers: Every bundle is tagged with its heat number, and the mill test report links that number to the mechanical and chemical results.

Structural framing of every kind: portal frames for sheds and workshops, mezzanine floors, stair stringers, balustrade posts, machine bases, conveyor gantries, racking and pallet support frames. It is also the default section for trailer chassis and for truck body sub frames. In agriculture it is used for implement frames and hay rack structures. Where the section is exposed to weather, we normally supply it primed and ready for a topcoat, or in the galvanized version of the same size.

Bundles up to 2 tons with three steel straps, waterproof paper and PVC sleeve, mill finish oiled before wrapping. Each bundle is tagged twice with heat number, size, wall thickness and grade, and bundles are separated by timber dunnage in the container so the corners are not bruised in transit. Mill test reports to EN 10204 3.1 come with every lot, and SGS or BV pre shipment inspection is available.

A note on ordering: A500 Grade B and the European S275J0H are close but not identical, and an inspector working to a European drawing will not accept an A500 certificate without a conversion. If the project is specified in EN 10219, tell us at the enquiry stage and we will supply the J0H route with the matching documentation instead of substituting.