Are here any ways to free threads on a pvc pipe trilby? I wanted to check the trilby on my sewer line which is...

I wanted to check the trilby on my sewer line which is contained by my basement. The pvc sou`wester is threaded and it has not be removed for a few years. How can I free this without forcing and cause other joints to loosen?
MY dryer works but it doesn't spin backing?
Answers:    try using a pipe wrench on the trilby and a use a strap wrench on the pipe to keep it from moving. try spraying the threads near liquid wrench and tolerate it set a couple of minutes before you try to loosen the sou`wester.
My boiler exploded! hose pouring out, big mess....
is pvc pipe in between wall? if so, you can seize some 2 x 4 and build a brace so it would not move.