fuel tanks

It's worth taking a moment at this point in the Guide to consider how important these particular Check List items are. A tank of fuel catching fire and exploding is one of the most serious risks anyone could face. Fortunately it very rarely happens these days because of the high level of safety these Check List items afford. If you want to find out more about the nature of fuels see appendix a.

Any damage to the fuel tank, pipework or fittings, caused by movement, could cause fuel to leak and create a dangerous situation. To reduce the risk of this happening fuel tanks must be properly secured.

It's recommended that your boat's fuel tank is installed as low as is practical to assist boat stability and reduce strain on the tank and its fittings.

To reduce the likelihood of the tank deteriorating, and fuel then seeping into the boat, fuel tanks must be made of corrosion-resistant material, which is suitable for the fuel being used.


Diesel fuel  Petrol
Untreated mild steel Aluminium alloy†
Mild steel* Lead-coated steel
Aluminium alloy† Brass
GRP Copper (tin coated internally)
Stainless steel Internally galvanised mild-steel
Fire-resistant polyethylene tanks†† Stainless steel
    Fire-resistant polyethylene tanks††


Diesel fuel Petrol
Lead coated steel Untreated mild steel
Copper Interior painted tanks
 Internally galvanised steel GRP

 *hot dip zinc coated after fabrication †containing not more than 0.1% copper. ††These must be suitable for use within inland waterways craft. Unsuitable types of plastic materials can be susceptible to cracking and permeation, leading to an accumulation of fuel vapour within the confines of a boat. Further advice and information sheets are available from the BSS Office.

If there is a fire near the tank, you will need to ensure that the tank materialdoes not immediately fail, leaking more fuel into the fire and causing it to escalate. Whatever material your tank is made of, it must have a fire resistance of at least 21/2 minutes (in accordance with BS EN ISO 10088). However, the greater the fire resistance, the more protection there will be from the risk of the tank failing.

To be sure of the sound construction of your fuel tank, so that it doesn't leak fuel during everyday use, your tank has to have undergone a pressure test of 0.25kgf/cm2 (or 3.5lbf/in2) before being used, and must be marked to indicate this. All joints and seams on tanks must be properly welded, brazed or closeriveted to sustain that test.

Boats built before 16 June 1998 do not need to comply with the requirement for pressure testing and marking on fuel tanks, but you do still need to make sure that tanks, joints and seams are not corroded or damaged to such an extent that leaks might occur. [2.6]

Looking for the flame trap on your vessel? It could be fitted in the handrailabove the fuel tank. This is quite a common practice with some narrowboat builders. The uprights of the rail form the vent pipe and the top of the tankwill have been drilled before the rail is fixed. [2.5]