Press-locked steel & stainless grating

What it is

Press-locked (also called pressure-locked) grating is a bar grating in which the cross bars are not welded to the bearing bars but pressed into notches cut in them under very high pressure. The cross bars are locked mechanically, finish flush with the top of the bearing bars and leave a clean, even surface in both directions. Because there is no forge weld at every intersection, the bars can be set much closer together than in standard welded bar grating, which opens up uses where appearance, small openings or heel safety matter more than maximum span.

Typical applications are pedestrian walkways and plazas, building facades and sun screens, ceiling and soffit panels, balcony and bridge decks, architectural stair treads, fence and gate infill, machine guards and plant screens. World Steel supplies press-locked grating as part of the platform, stair, canopy and facade steel it fabricates, so panels arrive with matching supports and fixings.

Types and options

Meshes are described by the bearing bar pitch and the cross bar pitch. Tight meshes give a near-solid walking surface and fine visual texture; open meshes save weight and let more light and air through. Bars are normally plain, with serrated or indented top edges available where slip resistance is needed.

Welded or press-locked? Welded grating is generally stronger and more economical for industrial floors and long spans. Press-locked grating costs more per square metre but gives tighter meshes, a flush top and a cleaner architectural appearance. Many projects use welded grating in plant areas and press-locked grating where the public walks or the facade is visible.

Design and compliance

Press-locked panels are designed like any bar grating: the bearing bars span between supports and are sized for the design load, clear span and deflection limit. Because cross bars rely on a mechanical lock rather than a weld, panels must be banded at cut ends and around openings, and the span direction must be marked on drawings and panels. Design loads follow ASCE 7, AS/NZS 1170.1 or EN 1991-1-1, and access platforms follow OSHA 29 CFR 1910 Subpart D, AS 1657 or EN ISO 14122-2. For US projects the NAAMM grating manuals (ANSI/NAAMM MBG 531) describe press-locked grating alongside welded types; in Europe DIN 24537-1 covers gratings used as floor covering.

For public areas, check heel and small-object requirements with the architect and the authority: a fine mesh such as 33 × 11 mm is often chosen for that reason. Facade and sun-screen panels are usually governed by wind load rather than foot traffic, so their supports and fixings are checked to AS/NZS 1170.2, ASCE 7 or EN 1991-1-4. See also design loads.

Fabrication and finishing at World Steel

Panels are produced to the project layout: bearing bars are notched, cross bars pressed in, panels cut to size and banded with flat bar welded around cut ends and openings, and each panel is marked with its layout mark and span direction. Dimensions, squareness and banding welds are checked under World Steel's ISO 3834-2 welding quality system before finishing.

Mild steel panels are hot-dip galvanised after fabrication by qualified galvanisers to ASTM A123, AS/NZS 4680 or EN ISO 1461; a powder-coat or paint topcoat can follow for colour. Stainless panels are pickled and passivated after welding – see stainless steel grating. Panels are packed by area for export shipping, together with the supporting steel or on their own.

Installation and specifying

• Fix floor panels with grating clips or bolted fixings; avoid site welding on galvanised or stainless panels.
• Facade and screen panels are normally bolted to a sub-frame with concealed or countersunk fixings and isolation washers where dissimilar metals meet.
• Keep a small gap between panels, bearing bars spanning between supports, and do not cut new openings on site without banding and the designer's approval.
• Specify mesh, bearing bar size or design load, span, material, surface, finish and fixing – or send the architectural layout and let World Steel propose the panel arrangement.