Here's the story, trying to tie in a stand pipe and trap for a washing machine discharge line in my friends basement. The old plumbing is 3" steel and I can not get the clean out cap to budge. It's 1 3/8" hex head but someone rounded the corners and I can't get a wrench to bite. I've tried lube and hitting it with a torch, suggestions I found online. Any suggestions on how to get the plug out? Thanks in advance!!