Ruptured fuel pipe and a thankyou

[RobinBirch]

A bit of drama off Lepe in the Solent on Monday. We were motoring en route from Southampton to Poole with no wind to speak off. I noticed that the fuel gauge indicated half full and going south rapidly. Pulled up the engine cover to find hot oil smoke and fuel spurting over the exhaust manifold from a leaking copper fuel pipe and what looked like 20 ltrs of fuel slopping around in Hanser's bilge. I killed the engine and attempted to sail towards Yarmouth without any progress. Drifting rapidly in the fast ebbing spring tide I called up Yarmouth HM who was unable to offer any assistance. Just on the point of calling up Solent coastguard a RIB came by and responded to my hail. A very big thank you to Neil (moored at Keyhaven) who then motored us into Yarmouth and refused any money for fuel etc but agreed to my suggestion of a contribution to the RNLI in lieu.

The leak turned out to be a fracture in the lift pump return pipe where it enters the secondary CAV filter. Unscrewing the nut allowed me to remove the broken stub end with its olive. Fortunately, there was sufficient 'slack' in the return pipe to re insert it back into the CAV unit and the helpful guys at Harold Hayles across the Yar bridge provided a replacement olive. So back in business quite easily.

A question...... any thoughts on why the fuel pipe broke? Overtightened or brittle fatigue perhaps? Also, if prone to fatigue should one consider replacement every 5 years or so?

I would appreciate your thoughts.

Robin

 

[vyv_cox]

Fatigue is certainly a possibility. No such thing as brittle fatigue. If the pipe exiting the fitting had a longish straight unsupported length it could well be subject to resonance and high displacement. This is a well known cause of fracture in any metal, not just copper. Worst case is a pipe as above but with something heavy attached to it, that vibrates with a large displacement and force, fatiguing the pipe early in its life. Support is the answer, so the pipe is unable to vibrate.

 

[RobinBirch]

Viv

Thanks for info. The pipe run in question is not particularly long and connects the fuel pump and secondary filter which are both attached to the engine and should all 'move' as one. I plan to change the pipe as a precaution.

 

[boaterbaz]

copper tubing does work harden with vibration becoming more brittle and and thus prone to fracture at stress points. Good support to reduce vibration and loading are essential.