How Flat-Sided Oval Tube is Driving Smarter Design and Manufacturing
For decades, circular tubing was the default choice for manufacturers, favoured largely for its availability and ease of bending. But as budgets tighten and expectations around performance, efficiency, and aesthetics rise, engineers are increasingly rethinking tube geometry.
One profile is emerging as a superior alternative across a diverse range of applications: flat-sided oval (FSO) tubing.
Timeless Tube MD Tom McMillan with flat-sided oval stainless steel 316L coil prototypes (23 x 12 x 1.5mm) for heat transfer
Since taking ownership of custom-tube manufacturer Timeless Tube a decade ago, Managing Director Tom McMillan has seen a surge in FSO specifications.
“Ten years ago, non-circular tube profiles were primarily specified in architectural applications, driven by aesthetics and ergonomics,” explains McMillan. “Today, engineers and manufacturers are increasingly recognising that FSO can improve product efficiency, simplify assembly, and support more effective production processes.”
Increased Deflection Strength
By redistributing material away from the neutral axis, FSO tube offers improved stiffness-to-weight performance compared to circular tube of equivalent mass. This is backed up by several independent deflection tests, where flat-sided oval has proven demonstrably stronger under load than circular tubing of the same mass (Timeless Tube’s own deflection test showed stainless steel FSO tube 48 x 21 x 1.5mm was 54% stronger than equivalent OD 38.1mm round tube).
FSO tubes are particularly well suited to applications such as structural supports, frames and load-bearing furniture components, where every gram and millimetre counts.
Solid bar-like integrity at a significantly reduced mass: internal brickwork cladding support made from folded flat-sided oval tube (16.9 x 3.5 x 0.5mm)
Flat faces for Easier Fabrication and Fixing
Equally important are its flat faces. These inherent planar fixing surfaces address one of the most persistent challenges in fabrication: how to fix reliably and repeatably to a tubular section. Where circular tube requires saddles, shims, or fabricated brackets to achieve stable contact, FSO tube requires few – if any –additional fixings.
“Components can be aligned directly to the flat faces, allowing for flush fixing and reduced assembly complexity.” explains McMillan. “In one project we pressed then machined bolt holes at the ends of an ultra-flat aluminium FSO support brace, which meant fewer additional parts, reduced tolerance stack-up and a quicker installation time.”
A Space-efficient Hollow Core
FSO tube’s usable hollow core and streamlined shape is valuable in industrial and high-hygiene sectors such as pharmaceutical and food manufacturing, where the profile is used to route hoses and cables while supporting efficient material flow.
FSO tubular handrails and vertical posts can also accommodate LED lighting, glazing panels, and hardware with greater ease than radiused circular tubing.
“In the last year we have made our largest and smallest FSO tubing to-date – for sheathing and conduit applications. We were required to laser-cut and swage these tubes, demonstrating how FSO can be reliably fabricated into components for production line parts” explains McMillan.
But additional processes such as laser-cutting can introduce new tolerance and distortion considerations. “We are continually expanding what we know about this versatile profile,but encourage early-stage collaboration with clients before trialling new sizes and ways to process this geometry.”
Flared flat-sided oval tube (14.6 x 7.5 x 1mm) is used to provide a smooth passage for critical aerospace cabling to pass through
Rethinking Tube Geometry for System Performance and Lifecycle Cost
Rather than defaulting to circular sections, engineers and OEMs are increasingly adopting FSO for performance, assembly efficiency, and lifecycle cost.
MRO specifiers are also recognising that FSO tube can help reduce downtime, speed up installation, and improve system performance over an asset’s lifecycle. FSO tube is effective for retrofit upgrades, replacement components, and system extensions, where reduced installation complexity and improved structural efficiency can simplify integration into existing assemblies.
For Timeless Tube, the combination of an extensive size range, flexible low-volume production (with a minimum order quantity of just one 5.7m length), and active R&D is helping make the transition to FSO practical for a growing number of manufacturers.
“Our cold-forming process provides a cost-effective and quick way for clients to prototype, order new sizes, and refine designs without committing to large production runs. But it’s not about replacing circular tube everywhere,” says McMillan. “It’s about giving engineers a better option where it makes a difference.”
Easy-fit end-caps provide economical tube finishing for high-volume furniture, shelving and transport applications
For further information on Timeless Tube’s flat-sided oval profiles and manufacturing capabilities, visit timelesstube.com
