The idea is that you use the Map16 editor
and copy the pipes into different tiles. New Map16 tiles start from page 2, btw. You then can select tiles from Direct Map16 Access (object window) or directly from the Map16 editor if you haven't opened object window.
Alternatively, if you don't want that all pipes are the same colour, you can use this hex edit instead:
db $EA,$A9,$00 ; $00 can be $01, $02 and $04, each are different colours
Okay, my layout looks ugly.