We installed a new vent pipe that goes from our basment to out side of roof we had to join two pieces were we joined them together there's water rolling out I guess it's condensation is this normal and now were going to half to take apart the pipes and seal them. Does this happen with the moisture all year round our old pipe was 100 years old and completey rusted out in large spots. Guess over time the moisture caused this. Thanks for any adivice.

Water trapped in a vent pipe? That shouldn't be. Vent pipes are pitched back towards the drain so this doesn't happen. If you have backfall or a dip in the line that fills up you have a blocked vent. Go back and make sure that ALL your vents have slope back to the drain it's venting. Good luck, Tom

No we don't have standing water we had a rusted vent pipe replaced it. We noticed that the old one was metal it rusted out since it is 100 years old we found a lot of moisture in the rusted one and in the new one which is now pvc , I'm assuming this is normal with some moisture in the pipe. But what causes it mabye it's due to winter mabye due to gases that turn to moisture just wandering.