Its the dreaded story of steel fuel pipes, they rot and corrode on 4X4's due to the environment they work in, but replacing them is relatively easy, if expensive if you go for manufacturer supplied fuel pipes which come pre formed and shaped.
One alternative exists in the form of copper pipe used in microbore plumbing systems, it comes in 6mm, 8mm, and 10mm bore pipe, and is available as semi soft or soft variants which makes it easy to form, and you need the plastic clips of the right size, singles for a single fuel pipe and doubles for twin fuel pipe set up's.
If you can solder and have a blow torch, flux, and solder, you can get a pack of olives of the same diameter as your pipe.
Remove your old fuel pipe/s and all the clips from the chassis, replace the clips with the new clips but dont fully tighten them down yet, unroll the roll of copper pipe and feed it through the clips to the flexible pipe at the fuel tank end, pull the end into position and shape it along its length to the original position the steel pipes took, allow a little spare and cut the pipe. You now have one full length of shaped fuel pipe in copper.
Remove sufficient pipe from the clips to ensure its far enough from the fuel tank so safely solder with a naked flame, if possible, remove the pipe all together and solder an olive 10mm (3/8th") from each end of the pipe, alternatively if you have a pipe flaring tool for that size of pipe you use you can put a single flare on each end, the object is solely to have a projection to put a jubilee clip behind to stop the pipe coming loose and falling off.
If you have soldered an olive on you may have to clean the soldering up a little, do this with a small, fine file, then smooth sandpaper to ensure no sharp or uneven bits which can leak or damage the flexible pipes.
If you have a twin pipe set up with a fuel return pipe you will have to repeat the above for the return pipe.
Place a small tie wrap at the back of the plastic mounting clip and tighten so it nips the tie wrap, then tie this over the front of the plastic clip to act as an additional retention for the pipe/s in its new clip.
You will now have new fuel pipes for less than the cost of manufacturer parts, and they won't ever rot again.