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.

SUITABLE MATERIALS INCLUDE:

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††

THE FOLLOWING MUST NOT BE USED:

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 material
does 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 handrail above 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 tank will have been drilled before the rail is fixed. [2.5]