I never had to modify my washer drain pipe. I think it's galvanized steel,
2".
I was flabbergasted once, years ago, to have a serious blockage. I had a
flood in my washing room because of it. It seems the detergent I was using
had caked the inside of the pipe, though I can't be sure. The problem
disappeared as mysteriously as it appeared. I had tried to flush the drain
with a hose, but that didn't work very well. What a mess that was.
I have long since changed to a different detergent. The problem never came
back.
A washing machine pumps a LOT of waste water in a short time.

"Duane Bozarth" wrote in message
...
orangetrader wrote:

I need to route a 3" PVC drain pipe from my garage (from the washer) to
the
kitchen drain.
....

Why 3"? 1-1/2 or 2 (max) would be more typical for a washer.

My first question is about the relative heights...can you get enough
drop to go 6' to an elbow and then another 4' to the down stack?
There's going to be a problem perhaps in getting good flow. Also, what
about trap and the vent?