Replacing fuel pipelines

I am currently replacing my original copper fuel lines. I see that on the fuel return line is a taps at the tank. I understand that nowadays no tap is put into the return line. Why was one put on orignally?

John B   

Dear John
The purpose of the tap is to enable prevention of fuel siphoning out of the tank in case a fuel line below tank level develops a leak. An alternative would be a one way valve.
It appears the Recreational Craft Directive does not specify valves on the return line, but the above reason is still valid.
Kind regards
Lars

Lars, thanks for the information. I have many inlet / outlets on my tank.

Fuel filling with an air breather. Fuel to engine, out and return, fuel for the heater and a small stainless outlet on the top of the tank with a short plastic pipe and non return valve in the end. Was this original and any idea what this might have been for?   

Thanks

Just a guess: the last stainless pipe could be the remnant of an Hart Tank Tender system. You may get a confirmation by checking if the pipe continues down to the bottom of the tank.
Do you have similar pipes in the water tanks and/or the toilet holding tank?
It is a quite nice and costly system and the previous owner might have thought it better to transfer it to his/her new boat!

Daniel, 411/004

Daniel, thanks will take a look.

For your information where the pipes run through the bulkheads they are fixed with a mastic, presumably to stop water ingress and damage due to rubbing. After 34 years I found that where the pipes had been in contact with the mastic the pipe colour was very orange indicationg greater levels of corrosion. So it might be worth a look at yours if not already replaced. I have also fitted a stop cock directly onto the racor filter as I found when changing filters diesel always split into the bildge. This is the residue fuel which remains in the pipe after you close the value at the tank.  

Picture shows the new fuel pipes fitted, we had to use a smaller gauge pipe on the return side of the system to get both pipes through exsiting holes. Also the new tap fitted to the Racor primary fuel  filter and seperator. We can now change filters without diesel getting into the bilges.