I have a shower downstairs where a 6" shower arm comes out of a wall that was connected to a 90 degree threaded joint inside the wall. My roommate without my permission took out the 6" arm and installed an 'S' arm. She did a poor job (did not take out the old thread/puddy, didn't put in new pipe thread, didn't caulk the metal circle that covers the hole in the wall). Although the concept is simple, a leaky threaded joint in the wall will cause a lot of damage, and is unnoticable until its too late. I took the 'S' arm out, got a new 6" arm, tried my best to take out old tape (the hole in the wall is only 1.5" by 1"), wrapped the pipe thread 3~4 times on the arm thread going into the wall, HAND tightened the arm, and checked for leaks on the threaded joint with the water on WITHOUT a shower head on. caulked the donut plate with silicone caulk.

My regrets:
I read installation of arms online, and it says to use a pipe wrench to tighten. I only used my hand. Although it was really tight according to my hand, I don't know if I could have done another rotation with a wrench to make it better

I didn't put the shower head on the pipe when checking for leaks. The water was just free flowing like a hose so I don't think it was a good test of the threaded joint. Should I have capped the arm and then checked the joint?? The metal donut is on now, so I can't see into the wall.

When putting weight on the arm, I notice the silicone caulk in the hole of the metal donut flexes with the arm slightly. Maybe up to a mm. Should I have used a caulk that dries hard to keep the arm firm?

I'm afraid of leakage I can't see in the wall, and a plumber would cost $75 to $85. What should I do to install this arm right? Since a plumber will undo what I did anyways, I'd like to try again.

speedball1

Since there isn't much back pressure from the shower head hand tightening the shower arm ought to be fine. You don't put a pipe wrench on chrome. If you want to snug up the shower arm pull the chrome escutcheon plate,(metal donut) down and snug up the arm with a pair of pliers. That way any nicks and scratches will be hidden. The shower arm is secured by two screws in the drop eared ell.(see image) and that is what keeps the shower arm tight not the caulking. I guess that you could pull the escutcheon plate down on the arm and turn the shower onto check it for leaks but we have very few shower arm leaks. Good luck, Tom