Stair gap closure panels

What it is

Industrial stairs built with open grating treads and no risers are light and easy to clean, but every flight leaves gaps through which a dropped bolt, a hand tool or a boot can pass: the open space between treads, the slot between the tread end and the stringer, and the triangle between the stringer, the bottom of the stair handrail and the landing. On stairs above walkways, conveyors or process equipment, those gaps are a common source of dropped-object incidents and of trips where a foot slips through the riser opening.

Stair gap closure panels are a set of bolt-on components that close those openings on an existing stair without replacing it. World Steel fabricates them in its Vietnam plant to measurements recorded flight by flight, and they are fixed by clamping to the tread load bars, nosings and stringers so that no welding is required on a live plant. They are normally supplied together with dropped-object prevention panels for handrails on the incline and landings, and with clamp-on toe boards on the platforms at the top and bottom.

Types and options

Riser closures can be perforated or mesh rather than solid so that the stair still drains and light passes through, provided the aperture meets the site's dropped-object criterion. That criterion – usually a test object of a stated size – is set by the site owner; World Steel selects the infill to suit it and records it on the drawings.

Design and compliance

Closure panels must not reduce the usable stair geometry. Riser closures sit behind the nosing line so that the going is not shortened, and side panels keep the clear width between handrails. For reference, OSHA 1910.25 requires standard stairs at 30°–50° with treads at least 9.5 in deep and at least 22 in wide; AS 1657-2018 allows stair angles of 20°–45° with goings of 215–355 mm; EN ISO 14122-3 requires 600 mm ≤ g + 2h ≤ 660 mm. A closure panel that projects into the tread would change those dimensions, so each component is detailed against the surveyed flight.

Added mass on old stairs is small, but corroded load bars, damaged nosings or loose stringer bolts should be repaired before panels are fitted. No test rating is claimed for the panels; site verification, if required, is defined by the site owner. Background on stair design is on the steel stairs and grating stair treads pages.

Fabrication and finishing at World Steel

Riser plates and strips are cut and folded on CNC equipment, triangle panels are welded on jigs set to the stair pitch, and clamp brackets are made from plate and bar. Welding follows qualified procedures under AWS D1.1, AS/NZS 1554.1 or EN ISO 3834-2. Parts are hot-dip galvanised by qualified galvanisers to AS/NZS 4680, ASTM A123 or EN ISO 1461, with optional safety-yellow edges on nosings. Each piece is marked with its flight and step number.

Installation and site notes

• Survey each flight: tread count and type, load-bar pitch, riser height, going, stringer section and handrail geometry.
• Fit riser closures from the bottom of the flight upwards, then stringer strips, then triangle panels.
• Barricade the area below and tether tools while working on the flight.
• Check all clamps after the first period of service and include the panels in routine dropped-object inspections.

Where a stair is beyond repair, World Steel can supply a new flight with closed risers and infilled handrails – see machine platforms and access platforms and walkways.