Why food plants use grating

Wet areas, wash rooms, filling lines and raw-material reception in food plants carry standing water, grease and washdown. The floor must drain and still support people working on it, and grating separates the two jobs: a walking surface above, a channel and services below.

Compared with checker plate, the open area lets water and debris fall straight through instead of spreading a film across the floor. Compared with concrete trench covers, FRP grating is light enough for one or two people with simple tools to lift, so inspecting the channel needs no lifting equipment.

Corrosion in a food plant does not come from water alone. Detergents, disinfectants, alternating acid and alkali, salt and organic residue act together. Carbon steel grating rusts quickly in this environment, and so does galvanized steel once repeated washing wears the coating away. The resin system of FRP grating can be selected for these media, which is the main reason it is used in food plants.

What hygiene design has to get right

The first rule of hygiene design is no hiding places. Openings should pass right through, the junctions between bearing bars and cross bars should not form closed pockets, and the surface should be flat without low points that hold water.

The second rule is cleanability. Grating should lift out so the channel, supports and corners can all be reached with a hose. Grating with too many fixed points gets skipped by the cleaning crew, and the underside becomes a contamination source over time.

The third rule is inspectability. During a hygiene audit, the auditor will look at the underside and edges. Cut ends must be sealed; otherwise glass fibre is exposed, which can shed particles and is hard to clean.

Cleaning and disinfectants

Common disinfectants in food plants include sodium hypochlorite, quaternary ammonium compounds, peracetic acid and hot water. They ask different things of the resin: sodium hypochlorite is a strong oxidizer and attacks resin more as concentration and temperature rise; quaternary ammonium compounds are milder but leave a film when residue builds up; peracetic acid is strongly oxidizing and is widely used on equipment and floors.

Resin selection cannot rest on acid and alkali resistance alone. Sodium hypochlorite is stable in alkaline conditions; in acid it releases available chlorine quickly and puts more oxidative stress on the resin. Where the cleaning cycle runs an alkaline wash followed by an acid wash, the grating sees both conditions in turn, and the resin must handle both.

Temperature and contact time matter just as much. Brief contact at room temperature and long soaking at 60 degrees Celsius are two different duties. Published chemical resistance tables usually state concentration and temperature, and results outside those limits cannot simply be assumed.

In practice, standing wash water is more common than the disinfectant itself. Insufficient floor slope, water trapped under the grating and poor rinsing after cleaning all keep chemicals in contact longer. Designing drainage and rinsing together is more effective than simply buying a higher resin grade.

Slip resistance and drainage

Wet areas and greasy areas carry the highest slip risk. Anti-slip surfaces on FRP grating usually use quartz grit or a profiled pattern, and dry and wet performance differ, so the specification should state that the duty is wet.

Grit size and how deeply the grit is embedded affect comfort underfoot and cleaning. Coarse grit is uncomfortable through soles and bare feet and traps dirt more readily; fine grit loses slip resistance quickly once it wears. Food plants mostly wear slip-resistant work boots, so a medium grit set deeply into the surface is a reasonable starting point.

Drainage depends on open area and orientation. Water passes more easily when the bearing bars run with the flow; where grating covers a channel, the open area must match channel width, slope and peak flow. To choose a surface for wet slip resistance, see anti-slip grating surface options

Colour and foreign-body risk

Food plants often choose blue, green or grey grating for foreign-body control rather than appearance. Blue is rare among food ingredients, so a broken piece is easier to spot, and a light surface shows dirt more readily.

Particle risk from FRP grating comes mainly from cutting and drilling. Cut edges must be sealed on site and dust cleaned up; after installation, check the channel and the area around equipment for loose fibre.

Colour also affects how ageing is judged. Dark surfaces absorb heat and tend to show colour difference after long ultraviolet and thermal cycling; pale surfaces show change more clearly, which helps plan replacement. State colour and colour-fastness requirements on the order.

Supports and installation

Under food-plant grating there are often drainage channels, pipework and equipment plinths, so supports are irregular. Support spacing must follow the load class of the grating and the actual span, not the panel thickness alone.

Prefer 316 stainless fasteners so carbon steel bolts do not rust in the wet environment and contaminate food-contact surfaces. Bolt heads should sit below the grating surface to avoid standing water and tripping; where panels are lifted often, stainless clips can replace bolts.

Leave a cleaning gap between the grating and walls or equipment plinths. Butting tight looks neat, but the joint cannot be flushed and becomes a place where micro-organisms grow. Edge trims should be removable or radiused, with no sharp edges. For installation practice in other sectors, see FRP grating industry applications

Common mistakes

The first mistake is treating FRP grating as maintenance-free. It does not rust, but it wears, ages and is attacked by strong oxidizers. A food plant should inspect the anti-slip surface, sealed edges and fasteners at least once a year.

The second mistake is buying on price without asking about resin. At the same size, orthophthalic and vinyl ester resins differ greatly in chemical resistance; in an area washed often with sodium hypochlorite, a cheap panel may show surface breakdown within a year or two.

The third mistake is ignoring supports. The panel may be thick enough, but with supports too far apart it deflects noticeably underfoot, and repeated movement loosens the fixings. Check load capacity and span together.

Specification and ordering

For an inquiry, give the service area, the type and concentration of cleaning chemicals, cleaning temperature, washdown frequency, ambient temperature, span, support arrangement, load requirement and colour. A request for food-grade grating alone gives nothing to work with.

Items to confirm include resin type, anti-slip surface, grating depth, open area, edge sealing and fastener material. Where a hygiene audit applies, add a material statement and a surface finish statement.

• State the service area, cleaning chemicals and concentration.
• List wet slip resistance and colour as separate requirements.
• Check span, supports and load against the real duty.
• Cover edge sealing, fasteners and spare panels in the same inquiry.

Grating in a food plant is not a standalone item; it works with the channel, floor slope and equipment layout. Putting process, cleaning and building conditions on one drawing at selection stage is cheaper than changing grating later. To check depth against span and load, see FRP grating specification tables