Different Types of 1/2" FIP Connections?

[Christopher Colby]

I've gotten a bunch of good advice off this forum over the past few years, but just ran into a perplexing question that I can't find referenced online.
Was installing a new Moen bathroom faucet, and grabbed two braided faucet supply lines at Lowes - 3/8 compression to 1/2" FIP. The 1/2" FIP connection would not thread on to the faucet. Tried every trick I knew to make sure the threads were lining up, but could not get them to grab. Both sides of the connection we're definitely the same size, but something just wasn't matching up. I grabbed the old supplies off the previous faucet, and they threaded right on. I've attached a photo with the two supply lines side-by-side.
Am I missing something obvious, or are there different types of 1/2" FIP supplies?

For the record, I'm not a professional plumber, but in my work I get into a lot of light plumbing tasks. Chances are I'll run into this again, and I'd like to know what's going on here. Thanks.

 

[hj]

As far as I have ever experienced, there is only ONE fip connector size, as is the faucet outlet, so I cannot imagine what problem you can be having.

 

[Sponsor]

 

[Reach4]

NPT and NPS I think have 14 threads per inch (TPI). You might get a thread gauge to help in your studies.

EDIT: The compression size thread pitch is a lot finer. That may be 28 TPI, but I am not sure.

If you press some modeling clay or soft wood into the threads to make an impression, you may be able to measure more easily.

 

[Dj2]

Call Moen customer service.
A lot of the new faucets are made in China and if Moen doesn't solve your problem, install another faucet.

 

[Kreemoweet]

That rubber washer on the new line looks pretty darn fat, it might be preventing the threaded nut
from meshing with the faucet threads. Can it be pulled out? Maybe that supply line was a return,
and the previous buyer stuck it in there for some reason. Customers are always returning damaged,
or modified goods to the big box stores, and the store just puts 'em right back on the shelves.

 

[hj]

Faucet connections have EXACTLY THE SAME thread as a 1/2 pipe thread, regardless of what some have written. The only difference is that they are NOT tapered.

 

[James Henry]

I MUST HAVE BEEN THINKING ABOUT SOMETHING ELSE !