Rectangular Hollow

An aluminium rectangular hollow section is the profile you reach for when a frame needs stiffness in one direction more than the other. Four walls, a closed box cross-section, and radiused corners straight off the extrusion press. The closed shape is the whole point. Where an angle or a channel will twist under off-centre load, a hollow section holds its line. We extrude rectangular hollows at our facility in Indonesia in 6063 and 6061, in stock sizes and to customer drawings.

What a Rectangular Hollow Section Is

The cross-section is a closed rectangle: a width, a depth, and a constant wall thickness running around all four sides. A 50 × 25 × 2 mm section gives you a 50 mm face, a 25 mm face, and 2 mm walls.

Because the profile is extruded from a single billet through a porthole die, there is no welded seam along its length. The corners carry a small external radius, which matters more than it sounds: radiused corners shed paint and anodising evenly, resist denting, and are safer to handle than a sharp folded edge.

One Profile, Four Names

This is a rare case where British and American buyers agree on the product name. In the UK, Australia, Canada, Europe, and the United States alike, the profile is a rectangular hollow, with only the spelling of the metal changing: aluminium on one side of the Atlantic, aluminum on the other.

Three other names circulate for the same extrusion. RHS (rectangular hollow section) is the standard abbreviation on UK and Australian structural drawings. Rectangular tube or rectangular tubing is the everyday term in the US market. Box section turns up in fabrication shops everywhere. Four names, one die. We quote against all of them.

Why a Closed Section Beats an Open One

Here is the engineering argument in one paragraph. Open profiles such as angles and channels are efficient in simple bending but poor in torsion: twist them and the thin walls warp. A closed box resists torsion through its entire enclosed area, which makes a rectangular hollow many times stiffer in twist than an open profile of the same weight. Any frame that takes load away from its centreline, a gate, a sign post, a cantilevered bracket arm, benefits from that closed shape.

Our position: if a frame member will ever see twisting or side load, stop comparing hollow sections with angles on price per metre. Compare them on the cost of the frame that does not rack.

Where Rectangular Hollows Get Used

• Frame structures for canopies, partitions, machine guards, and display systems, where the section is both the structure and the finished surface.
• Fencing and gates, where stiffness against wind load and slamming matters as much as static strength.
• Support posts and rails in shopfitting, balustrade infill, and furniture.
• DIY and light fabrication, because the flat faces take screws, rivets, and brackets without special fittings.

Specifications

Sizes outside this range, and non-standard wall thicknesses, can be extruded from our die library or from a new custom die against your drawing.

Orientation and Wall Thickness: The Two Decisions That Matter

A rectangular section is only efficient if it points the right way. Bending stiffness rises with the cube of depth, so a 50 × 25 mm hollow loaded on its deep axis is roughly four times stiffer than the same profile laid flat. Set the long face against the load. Always.

Wall thickness is the other place buyers economise and regret it. The walls rarely fail in the span; they fail at the connections, where a screw strips out of a 0.9 mm wall that a 1.6 mm wall would have held. If the joint carries load, specify the thicker wall or tell us so we can recommend one. The price difference is small. The rework is not.

For frames loaded evenly from all sides, the symmetric version on our Square Hollow page is often the simpler choice.

Custom Rectangular Hollows from Indonesia

Three service levels, same as every profile we extrude:

1. Cut-to-size from standard dies. Send a cutting list and receive finished lengths with square, deburred ends.
2. Non-standard dimensions or wall thicknesses from the existing die library.
3. A custom die for proprietary sections, including internal screw bosses, fins, or asymmetric walls.

Send your drawing, cutting list, or even just the load case, and our team will come back with an alloy recommendation, price, and lead time from our factory and warehouse in Indonesia. Request a sample length first if you want to check the finish and wall feel before the production run.