Four duties in a shipyard

Grating in a shipyard and dry dock faces four duties at once: wet slip, welding hot work, heavy load and impact. They overlap in the same area, so a choice based on one figure, whether slip or capacity, will fail on another.

The ground is wet and oily all year, and cabins, pump rooms and quay edges also carry mud and grit. Welding and cutting throw sparks and slag that can burn the panel, while the temporary loads from blocks and equipment are far above those of an ordinary walkway. Those points set the surface, resin and depth.

Docks and quays also feel the tide, and supports may be immersed intermittently. Fixings, supports and cut edges must be designed for wet-dry cycling, not copied from an indoor platform.

Wet slip and oil

Wet slip in a shipyard comes from three sources: wash water, rain and oil. Oil in engine rooms, pump rooms and deck areas is the hardest because it forms a continuous film; clean water and oil place different demands on the surface, and grit is usually more reliable.

Drainage has to follow the hull slope and the quay slope. Bar direction and cross bar spacing change how fast water leaves, and once the hollows hold oil the grip falls quickly, so the cleaning interval is set by the oil load.

Shipyards wash with high-pressure water, and a jet held close strips grit. Grit panels need a controlled washing pressure, or a product with deeper particle encapsulation; after washing, check that the grit is even, because shiny patches mean the particles have worn.

Slip class selection is covered under anti-slip FRP grating practice

Welding sparks and hot work

Sparks from welding, burning and grinding reach over a thousand degrees Celsius, and slag landing on the grating burns the resin and leaves craters. FRP is not non-combustible; a fire-retardant resin slows burning but cannot take sustained heat.

Hot work areas should cover the grating with a fire blanket or steel plate and be checked for smouldering afterwards. Resin dust, oil and debris on the underside are combustible, and a spark falling through the grid can ignite them below, which is especially dangerous in cabins and pipe spaces.

The hot work permit should list the grating: clear combustibles before work, post a fire watch during it, and recheck for the period the project requires afterwards. Burnt grating must be replaced or repaired, not painted over.

Heavy and temporary loads

Shipyard platforms often carry temporary loads from blocks, equipment and tooling, and both the value and the position change. Grating selection must check the worst concentrated load and leave margin in the support layout, not just read a uniform load table.

During block transport and lifting, grating may be used as a temporary deck and take forklift and pallet traffic. That is outside the design range of walkway grating; steel plate or a dedicated deck should be used instead, and the practice should not be allowed by default.

The deflection limit follows how the walkway feels and how it drains. Heavily loaded areas need shorter spans and closer supports, and pultruded or steel grating may be needed; FRP has low modulus, so long spans under heavy load are rarely economic, and the overall platform layout is covered under industrial work platform solutions

Impact and knocks

Falling loads and collisions are more frequent in a shipyard than in a general factory. FRP grating resists impact through its integrity and toughness, but repeated impact cracks the resin and separates the fibre layers; cracks run outward from the impact point, and the surface may show only a white mark.

FRP grating platforms should not sit below lifting operations. Where that cannot be avoided, add temporary protection above the panel or switch the lifting area to steel grating; damaged panels must be assessed for residual capacity and not returned to service.

Edges and openings are the most impact-sensitive places. Banding and reinforced edges spread the impact, and the banding must be properly connected to the bearing bars rather than fitted as decoration.

Site cutting and fitting

Platform shapes in a shipyard are complex, so site cutting is unavoidable. Molded grating cuts in either direction, and the open grid at the cut needs edge sealing; pultruded grating tolerates cuts along the bearing bar, but a cross cut severs continuous fibre and must be avoided or reinforced.

Ordinary woodworking tools are enough, but they produce glass fibre dust. Operators need a dust mask and goggles, the cutting area should be isolated and extracted, and dust must not be discharged into cabins or pipe spaces.

Openings should stay away from the middle of bearing bars and from high-stress zones. Distances from a hole to a support and between holes follow the manufacturer's data; several holes close together need a secondary beam or a deeper panel, and general cutting and fixing requirements are covered under FRP grating fasteners and installation

Fixing in tidal and dock conditions

Supports at docks and quay edges may be immersed intermittently with the tide. Fasteners must resist chloride, and carbon steel is consumed quickly in wet-dry cycling even when galvanized; stainless contact with FRP needs an isolating layer to prevent galvanic corrosion.

Grating must not be locked on all four edges. Long walkways move with temperature and hull deflection, so fixed at one end and sliding at the other is safer; grating on floating docks and shiplifts must also allow for platform deformation and small movement at each fixing.

The fixing problems on offshore platforms and in shipyards are similar, and the practice is described under FRP grating for marine environments

Maintenance and repair

Shipyard grating inspection covers cracks, burns, grit wear, fastener corrosion and support distortion. Grating in cabins and pipe spaces is easily overlooked, so the inspection plan should list those concealed areas separately.

Small damage can be repaired with the specified resin: grind, clean and dry first, then seal the repair with edge resin. Panels with large cracks, separated fibre or burn-through should be replaced as a whole, not patched and left to carry load.

Repair records should match the panel position so the next inspection can compare. Areas repaired more than once usually point to a problem with use, and the cause lies in the load or the protection rather than the panel.

Selection and purchasing points

The inquiry should state the area, load, slip requirement, distance from hot work, corrosive environment and fixing method. Conditions vary widely inside a shipyard, and engine rooms, decks, quays and docks cannot share one specification.

Resin follows the oil, salt spray and cleaning agents, and the fire class follows the project's fire requirement. Panel depth, bearing bar height and support spacing are settled together, not by choosing a panel and changing the supports afterwards.

The delivery state must be clear: banded or not, pre-drilled or not, edge sealed or not, fasteners included or not. Every extra site operation adds dust and damage risk.

• List load and slip requirements by area.
• Mark protection measures in hot work zones.
• Confirm fastener material for tidal zones separately.
• Write banding, openings and edge sealing into the order.