Black Painted Carbon steel square tube 60x60x4mm EN 10219 S275J0H Welded Hollow Section

This 60 x 60 x 4 mm hollow section is supplied in the European route, EN 10219 S275J0H, and finished with a black shop primer so it can go straight into an exposed frame without a separate blast and paint step. At 7.03 kg per metre it is a genuine structural member: a 6 m length is 42 kg, and the 4 mm wall carries a tapped M12 fixing without any doubler plate.

S275J0H means 275 MPa minimum yield, impact tested at 0 degrees Celsius with 27 joules minimum, and H for hollow section. That impact requirement is the part buyers overlook. A section that will be welded into a structure and then loaded in a cold climate should not be ordered on yield alone, and the J0 designation is what tells the inspector the steel has been impact tested rather than assumed impact capable.

• S275J0H Full Specification: 275 MPa minimum yield with 27 J impact energy at 0 degrees Celsius, certified on the mill test report rather than declared.
• Shop Primer Applied: Black alkyd or epoxy primer at 40 to 60 microns dry film, applied after degreasing, which holds the surface for up to six months indoors.
• 4 mm Wall for Threaded Fixings: Enough wall thickness for M12 tapped holes and for welded cleats without punching through the face.
• Controlled Weld Quality: Weld is continuous along the corner with a smooth transition, and a flattening test is run per shift to prove the seam.
• Dimensional Accuracy: Outside dimension held to plus or minus 0.5 mm and wall to plus or minus 10 percent, which matters when the tube is part of a bolted assembly.
• Lengths to Suit Fabrication: 6 m and 12 m as standard, with cut to length, mitred ends and drilled holes available as a value added service.

Exposed structural frames are the natural use: canopy and carport structures, stair and balustrade posts, mezzanine columns, machine frames, gantry legs, sign structures and architectural feature frames that will be top coated on site. It is also common in agricultural and industrial sheds where the frame is painted rather than galvanized. On welded assemblies the primer within 25 mm of a weld should be removed before welding, and the joint re primed afterwards.

Primed tube needs more care in transit than bare tube, because the coating is only 40 to 60 microns and marks easily. Bundles are limited to 2 tons, strapped with three steel strips over soft packing, wrapped in waterproof paper and sleeved, with timber dunnage between bundles in the container. Two tags per bundle show heat number, size, wall and grade. Certificates to EN 10204 3.1 with impact results are issued per lot.

Practical point for fabricators: alkyd shop primer must be removed before welding, and if the frame will be powder coated the primer has to be compatible with the powder system or it will outgas and blister at cure temperature. Tell us which topcoat system you are using and we will match the primer to it at no extra cost.