Overview
ISO 24681:2023 - Ships and marine technology - Fibre-reinforced plastic gratings - specifies the structure, technical requirements and test methods for fibre-reinforced plastic (FRP) gratings used on ships and offshore platforms. The standard covers terminology, classification (moulded and pultruded gratings), manufacture, inspection and performance testing for self-supporting FRP gratings intended for pedestrian pathways, platforms and stair treads in maritime environments.
Key topics and technical requirements
The standard addresses design, manufacturing and verification aspects with emphasis on safety and durability. Key points include:
- Types and construction: distinguishes moulded and pultruded FRP gratings, with typical mesh sizes and bearing-bar profiles described for selection and specification.
- Appearance and quality: requirements for surface finish (no obvious stratification, fibre exposure or cracks), pore limits (no pores > 3 mm; ≤10 pores between 1–3 mm per 300×300 mm) and warpage limits (≤2.5 mm/m along bearing bars; ≤5 mm/m other directions).
- Load-bearing capacity: minimum flexural strength of 345 MPa; design load criteria for pedestrian pathways and platforms (uniform load specified in the standard) and deflection limits (mid-span deflection ≤ span/120 and maximum deflection ≤ 9 mm). Stair treads are assessed for a 2 kN concentrated load with tighter deflection limits (≤ span/200; max 6 mm).
- Corrosion and environmental resistance: requirements for seawater and salt-fog resistance; post-salt-spray load-bearing verification.
- Skid resistance: average coefficient of friction for the upper surface ≥ 0.75 (dry conditions).
- Fire performance: surface flame-spread testing per IMO FTP Code (Part 5) or equivalent (e.g., ASTM E84 - FSI ≤ 25); smoke and toxicity testing per IMO FTP Code with equivalence to ASTM E84 SDI ≤ 450.
- Anti-electrostatic properties: conductive surface and grounding requirements for hazardous areas (see IEC 61892-7 and numeric limits in the standard).
- Testing and inspection: prescriptive test methods for flexural loading (three-point bending), flame integrity, UV exposure, salt spray and other acceptance tests. Annexes include normative test procedures and an informative application guideline.
Practical applications and who uses this standard
ISO 24681:2023 is essential for:
- Naval architects and ship designers specifying deck, walkway and platform materials.
- FRP grating manufacturers and fabricators ensuring product compliance.
- Classification societies, shipbuilders and offshore operators for procurement, inspection and acceptance.
- Safety and maintenance engineers assessing skid, fire and corrosion performance in maritime environments.
Using this standard reduces ambiguity in specifications, improves safety on ships and offshore platforms, and ensures consistent quality and testing of FRP gratings.
Related standards and references
Normative references cited include: ISO 4892-3 (UV exposure), ISO 9227 (salt spray), ISO 14125 (flexural properties of FRP), IMO FTP Code, SOLAS, ASTM D2047, ASTM E84, and IEC 61892-7. Consult the full ISO 24681:2023 document for complete numeric limits, test methods and annexed procedures.