Small craft — Permanently installed petrol and diesel fuel tanks
1Key Takeaways
This document specifies requirements for the design, ins tallation and tes ting of petrol and diesel fuel tanks for internal combus tion engines, that are intended to be permanently ins talled in small craft.
2Expert Interpretation
An in-depth analysis of the third edition of ISO 21487:2022 on the design specifications, material requirements, pressure testing and fire testing standards for permanently installed gasoline and diesel tanks on small ships, covering the installation specifications and permeation emission control technologies for metal and non-metallic tanks.
Analysis of the core content of the standard
| Items | Gasoline tank | Diesel tank |
|---|---|---|
| Installation method | Integration with the hull is prohibited | Integration/non-integration is allowed |
| Material thickness | Aluminum ≥2.0mm, Steel ≥1.5mm | Stainless steel ≥1.0mm, galvanized steel ≥1.5mm |
| Key tests | Pressure pulse test (25,000 cycles) | Static pressure test (5 minutes) |
Technology Evolution and Standard Updates
The main updates of the 2022 version include: adding a new penetration test appendix (Annex A), expanding the scope of installation requirements, revising metal material clauses 4.2/4.3.9/4.4.1, and reconstructing diesel tank test clause 6.2. Among them, the penetration emission control requirements for non-metallic fuel tanks reflect the global environmental protection trend.
Key test requirements
Fire test specifications
Non-metallic fuel tanks must pass two fire tests:
- General test (7.4): 650°C flame for 2.5 minutes
- Installation simulation test (7.5): needs to be verified in a simulated hull environment
After the test, the air pressure of 1.8kPa must be maintained without leakage
Implementation recommendations
- A galvanic corrosion barrier must be set between copper alloy accessories and aluminum fuel tanks
- The opening area of the baffle shall not exceed 30% of the cross-section
- The minimum inner diameter of the ventilation pipe is 11mm, and the pressure must be controlled ≤80% of the test pressure
- The marking requirement includes 6 items of information such as capacity, fuel type, and test pressure