Does this pipe located below a laundry sink need a p trap?
theanswer is yes. the vertical pipe needs to be capped off.
There needs to be a trap inline somewhere…look in the basement or crawlspace or whatever is below the tub, it’s possible it is located there.
Yes and the vertical section is the vent and configured the way it is the only fix I see is adding an AAV to the top. Otherwise sewer gases can enter the home.
Yes… You also should mention that the vertical pipe “vent” should be connected to a proper vent pipe unless it is legal in your area to have what is called a cheater vent.
Also, looks like PB supply lines!