Why this ducting earns its place
Combisteel square pipe ducting is the backbone of a working extraction system. At 400 mm square section, this pipe sits in the mid-range for commercial kitchens — large enough to handle real airflow from hoods and cooking equipment, compact enough to route through typical ceilings and plant spaces. The aluminium construction keeps weight down (3 kg per section) while resisting the corrosion and grease that shortens the life of cheaper alternatives.
Square section ducting is the standard for commercial systems because it sits flat against walls and ceilings, uses space efficiently, and connects predictably to hoods, fans, and dampers. At 400 mm, you're moving serious volume — adequate for multi-station kitchens, extraction canopies over cooking lines, or joining multiple smaller branches into a single exhaust route.
Installation is straightforward: bolt or rivet to flanged components, seal joints with silicone or gasket, and tape any rough edges. The section holds rigid during installation and keeps its shape under the flexing and vibration that softer ducting can't withstand. Because it's aluminium, it won't rust if moisture sneaks into the ductwork, and it's light enough that ceiling fixings and supports aren't overkill.
