I am about to replace the old 40 yr Galv drain piping on my slop sink because of very slow draining. My washing machine drains in to it. I want to install solid PVC 1 1/2". It has a saddle on the 4" cast iron sewer, past the main 3" stack.and is 1 1/2" Galv. Do I need a trap on sink? even though I have a trap on main sewer at clean-out. Thanks John::confused:

EVERY FIXTURE THAT HAS A DRAIN NEEDS A TRAP AND A VENT. The running trap on the sewer line has nothing to do with the fixtures in your house. Good luck, tom

Tom- how do I INSTALL A VENT?