Basic unix philosophy is everything is a file
So yes, there is a pipe file.
This link helps explain
Some systems provide the pathnames /dev/stdin, /dev/stdout, and /dev/stderr. These are equivalent to /dev/fd/0, /dev/fd/1, and /dev/fd/2.
Unless I'm mistaken, this can be very similar
command1 | command2 | command3
command1 output to stdout, command2 takes command1's stdout as its stdin, processes it and sends the output to stdout, command3 takes command2's stdout as its stdin, processes it and sends it out to stdout, which is then interpreted by /dev/tty (the current terminal process) and displays it on screen.