petrol line vs piping

petrol line and piping both are nouns.

Word	Noun	Adjective	Verb	Adverb
petrol line	Yes	No	No	No
piping	Yes	No	No	Yes

As nouns, piping is a hypernym of petrol line; that is, piping is a word with a broader meaning than petrol line:

petrol line: a pipe that carries gasoline from a tank to a gasoline engine
piping: a long tube made of metal or plastic that is used to carry water or oil or gas etc.

Other hypernyms of petrol line include pipage, pipe.

petrol line (noun)	piping (noun)
a pipe that carries gasoline from a tank to a gasoline engine	playing a pipe or the bagpipes
	a long tube made of metal or plastic that is used to carry water or oil or gas etc.
	a thin strip of covered cord used to edge hems

petrol line (adverb)	piping (adverb)
	(used of heat) extremely