Keeping underground air-extraction vents corrosion free. 

Midland Alloy Ltd, based in Telford, Shropshire, is a specialist aluminium engineering company with expertise in forming complex structures through section bending, complex CNC machining and welding. The company is well known for intricate exacting work and recently won a contract to produce leading-edge aluminium air vents for an underground car park at the re-developed San Francisco Civic Centre Plaza.

The redesign of the plaza area has been continuing for over three years with one objective being to tie the various parts of the plaza together by opening up and improving the public spaces and removing parked cars from the roadside where they impede the flow of pedestrians. Redesigning and extending the underground car parks are an essential part of the redevelopment.
The air extraction vents comprise a cylindrical frame with curved louvres attached in rings around the outside of the frame. This is topped by a conical lid, in two sections, resembling a cymbal cut into two. The louvres and lids have a unique design which must be manufactured to a high degree of accuracy from 3.2mm aluminium in order for them to function efficiently. Protective coatings for the metal needed to  be applied with an accurate and even thickness to meet the critical tolerances.