riser vs pipage

riser and pipage both are nouns.

Word	Noun	Adjective	Verb	Adverb
riser	Yes	No	No	No
pipage	Yes	No	No	No

As nouns, pipage is a hypernym of riser; that is, pipage is a word with a broader meaning than riser:

riser: a vertical pipe in a building
pipage: a long tube made of metal or plastic that is used to carry water or oil or gas etc.

Other hypernyms of riser include pipe, piping.

riser (noun)	pipage (noun)
structural member consisting of the vertical part of a stair or step	a long tube made of metal or plastic that is used to carry water or oil or gas etc.
a vertical pipe in a building	a fee charged for the use of pipes
a person who rises (especially from bed)