ISO 23949:2023

Overview

ISO 23949:2023 - Plastics - Application of spread of flame test to plastic pipes - specifies how to assess surface flame spread for plastic pipes, including fiberglass reinforced plastic (FRP) pipes, primarily for use in ships, aircraft and vehicles. The standard adapts the lateral spread test of ISO 5658-2:2006 to pipe geometries and provides detailed specimen preparation, conditioning, test procedures and reporting requirements to ensure repeatable reaction-to-fire results.

Key topics and technical requirements

• Test principle: Uses the ISO 5658-2 lateral spread-of-flame method with additional pipe-specific protocols (radiant heat flux exposure, time-to-ignition, lateral spread and extinguishment observations).
• Specimen preparation:
  • Pipe sections cut to 800 mm length.
  • For rigid pipes: lateral cutting rules depending on inner diameter (e.g., curvature height ≤ 5 mm if ID > 10 mm; split into two parts if 5 mm < ID ≤ 10 mm; full section used if ID ≤ 5 mm).
  • Wall thickness: test at full thickness if ≤ 40 mm; reduce unexposed face to 40 mm if > 40 mm (record original thickness).
  • Assembly: place sections side-by-side on a non-combustible backing board (155 mm × 800 mm, 20 mm thick, nominal density 900 ± 100 kg/m³) and secure with thin metal wires or wire mesh where deformation can occur.
• Number of specimens: At least six specimens unless agreed otherwise.
• Conditioning: Constant mass at (23 ± 2) °C and (50 ± 5) % RH; constant mass defined by two weighings 24 h apart differing by ≤ 0.1% or 0.1 g.
• Test execution: Use ISO 5658-2 apparatus and calibration; account for possible large fume/gas production for thick-walled pipes and ensure adequate exhaust.
• Results and calculations: Derive average heat for sustained burning (Qsb) and critical heat flux at extinguishment (CFE) per ISO 5658-2.
• Reporting: Include time to reach standard 50 mm positions, observations, derived characteristics (Q and C), specimen description, test conditions, number of specimens, ignition time and limitations.

Applications and practical value

• Ensures consistent, repeatable assessment of flame spread on plastic and FRP piping used in maritime, aviation, automotive and land-based installations.
• Supports product development, material selection and compliance evidence for designers, shipbuilders, aircraft and vehicle manufacturers, and fire safety engineers.
• Useful for manufacturers and testing laboratories seeking standardized methods to demonstrate fire performance of pipe systems and to inform risk assessments and regulatory submissions.

Who should use this standard

• Pipe and composite (FRP) manufacturers
• Accredited fire testing laboratories
• Maritime, aviation and automotive OEMs and suppliers
• Fire safety engineers, certification bodies and regulators

Related standards

• ISO 5658-2:2006 - Reaction-to-fire tests - Spread of flame - Part 2 (lateral spread)
• ISO 13943 - Fire safety - Vocabulary
• IMO guidelines on use of plastic pipes (referenced in the introduction)

Keywords: ISO 23949:2023, spread of flame test, plastic pipes, FRP pipes, ISO 5658-2, flame spread, reaction-to-fire, pipe fire testing, maritime fire safety.