Overview
ISO 21487:2022 - "Small craft - Permanently installed petrol and diesel fuel tanks" - specifies requirements for the design, installation and type testing of petrol and diesel fuel tanks permanently fitted in small craft (recreational boats and similar watercraft up to 24 m hull length). The third edition (2022) updates material, installation and testing requirements and adds Annex A on permeation (evaporative emissions) testing for non‑metallic petrol tanks.
Key topics and technical requirements
- Scope and definitions: Covers permanently installed, integral and non‑integral tanks; defines terms such as petrol, diesel, integral tank and tank range.
- Materials and corrosion resistance: Specifies suitable metallic materials and minimum nominal sheet thicknesses for corrosion resistance (examples include aluminium alloys, stainless steel, mild steel with coatings, copper with internal tin coating) and allows alternative materials if equivalent resistance can be demonstrated.
- General tank provisions:
- Seals must be non‑wicking and materials resistant to contact liquids (fuel, oils, sea water).
- Fill, ventilation and fittings rules (e.g., minimum fill/vent diameters and top‑mounted openings for petrol tanks).
- Baffle design limits (open area ≤ 30% of tank cross‑section).
- Installation:
- Non‑integral tanks must be mechanically fixed so loads from a full tank are safely distributed; flexible continuous supports preferred.
- Avoid water‑trapping exterior surfaces on metal tanks; isolate metallic supports to prevent corrosion.
- Installation interfaces (fill, vent, fuel circuit) should comply with ISO 10088:2022.
- Design and type tests:
- Petrol and diesel tanks subject to leakage, pressure/strength and pressure‑impulse tests (as applicable).
- Non‑metallic petrol tanks require fire‑resistance testing; Annex A provides permeation testing procedures to assess evaporative emissions.
- Marking and inspection: Tanks must be appropriately marked and diesel tanks require access hatches and shut‑off provisions for drains and sight gauges.
Practical applications - who uses ISO 21487:2022
- Boatbuilders and OEMs designing and manufacturing permanently installed fuel tanks.
- Naval architects and marine engineers specifying tank materials, mounting and integration with craft structure.
- Fuel tank manufacturers developing metallic and non‑metallic tank ranges and conducting type tests.
- Surveyors, classification societies and regulators verifying compliance for safety, structural integrity and environmental (evaporative emission) requirements.
- Installation and service technicians ensuring correct mounting, venting and maintenance practices on small craft.
Related standards
Keywords: ISO 21487:2022, small craft fuel tanks, permanently installed petrol and diesel tanks, tank design, tank installation, fuel tank testing, permeation testing, evaporative emissions, marine fuel systems.
