Here's how:
Verb:
* Past tense of "pipe": He piped the music into the room. (meaning: played the music through a pipe or instrument)
* Meaning: to convey through a pipe: The water is piped directly to the house.
Adjective:
* Meaning: conveyed through a pipe: A piped gas system.
* Meaning: resembling a pipe in shape: The piped edging of the cake.
Therefore, the part of speech of "piped" depends on its context in a sentence.