QUestion about pipe threads for plumbers

[tigerwoodKhorns]

I want to replace a shower arm from the connection in the wall to the shower head. 

 

I bought a $10 arm on Amazon and had to return it.  The threads are not sharp and I could not screw it into the fitting in the wall.  I did not want to force it.

 

So I ordered a Moen arm from the Home Depot.  In the picture you can see nice sharp threads. 

 

https://www.moen.com/products/Moen/Moen-Chrome-6-Shower-Arm-Shower-Arm-with-1-2-Inch-IPS-Connections-6-L-x-75-W-x-75-H-/10154

 

But what I received looks just like the Chinese arm.  Look at the threads, they are square on top rather than the sharp threads that you usually see on pipe threads. 

 

Have pipe threads changed?  I do not want to force anything and these threads will need a bunch of Teflon tape and will need to be forced. 

 

 

 

[Tom05]

1 hour ago, tigerwoodKhorns said:

I want to replace a shower arm from the connection in the wall to the shower head. 

 

I bought a $10 arm on Amazon and had to return it.  The threads are not sharp and I could not screw it into the fitting in the wall.  I did not want to force it.

 

So I ordered a Moen arm from the Home Depot.  In the picture you can see nice sharp threads. 

 

https://www.moen.com/products/Moen/Moen-Chrome-6-Shower-Arm-Shower-Arm-with-1-2-Inch-IPS-Connections-6-L-x-75-W-x-75-H-/10154

 

But what I received looks just like the Chinese arm.  Look at the threads, they are square on top rather than the sharp threads that you usually see on pipe threads. 

 

Have pipe threads changed?  I do not want to force anything and these threads will need a bunch of Teflon tape and will need to be forced. 

 

 

 

A good tapered pipe  thread should screw into a fitting about 2 /1/2 turns by hand (ideally).Threads are sometimes improperly cut overly deep or too shallow, this effects how many turns necessary until the fitting tightens . a much too shallow cut would prevent the pipe from starting. If it seems too tight to start ,test it by  screwing it into a  steel  fitting that you may have laying around , Also the first thread could be bad ? a file would fix that , good luck 🤓

[Racer X]

That is odd, but perhaps for the water, the threads need to be very tight.  Yes, two or three rounds of Teflon tape required, be sure you wind it in proper direction.  Good luck -- Plumbing is a nightmare.

[tigerwoodKhorns]

55 minutes ago, Tom05 said:

A good tapered pipe  thread should screw into a fitting about 2 /1/2 turns by hand (ideally).Threads are sometimes improperly cut overly deep or too shallow, this effects how many turns necessary until the fitting tightens . a much too shallow cut would prevent the pipe from starting. If it seems too tight to start ,test it by  screwing it into a  steel  fitting that you may have laying around , Also the first thread could be bad ? a file would fix that , good luck 🤓

 

The old pipe will screw in but the newer square thread pipes will only go in about 1/2 turn before you need to force them.  I really do not want to have to cut the drywall on the other side and replace the fitting in the wall. 

 

Oddly, both the old and new pipes screw into the showerhead easily. 

 

[the real Duke Spinner]

Pipefitter here

Of 50 years

That is crap

Take it back I only buy Peerless or Kohler fixtures

There is mostly junk out there

People want cheap... They get it Go to a plumbing supply house

[the real Duke Spinner]

BTW

Dope and Tape may required