Rubbing pipes

I always have a poke around the engine to identify problems which may eliminate a potential roadside breakdown. On the left-hand side of the 1.2 tsi engine there are a pair of pipes strapped together which run over the top of a single pipe. Always inquisitive I lifted the top pair of pipes to find that they have been rubbing on the bottom pipe with the tell-tale mark on the elbow. What is also annoying is that the webbed reinforcement sleeve finishes short of the rubbing area. What do the pipes carry? If it is fuel what a bad design and routing of the pipework to allow rubbing and eventually failure of perhaps catastrophic result. First picture shows my finger pointing at the pipe and the second picture showing the rubbed area on the elbow.