Leaking threads on expansion tank

[mikeh85]

Had to replace my water heater this past weekend along with the expansion tank. All my new work is PEX and I have no issues with the crimped connections. However I had to resort to using a Sharkbite 3/4 x 3/4 FIP elbow for the expansion tank mount, this was the only one I could source locally on the weekend.

There's a pinhole in the threaded connections I can't get to stop. I've tried 3 times to re-seat this connection (completely removed tank) using new Teflon tape each time. Should I try with pipe dope? Or just get a new 3/4 FIP elbow? There are no nicks or damage to the threads on either side that I can see.

Thanks for any suggestions,
-Michael

 

[frodo]

remove the tank and use pipe dope NOT TEFLON TAPE

in the image you provided. it looks like you are using a all thread nipple
replace the nipple with a 3'' nipple. something a wrench can grab

 

[Jeff Handy]

Also support the tank with a loop of plumbing strap hanger or similar support.

Lots of stress on that connection with water in the tank for many years.

 

[mikeh85]

Thank you both! I will try again with pipe dope.

Also, yes, the tank is supported from the floor joists with hanging strap.