How to connect 14 thread pipe to 18 thread pipe

Question

I am trying to install a gas dryer. I noticed that the gas pipe from the dryer (yellow) wouldn't lock with the gas pipe coming from the ground. They are both the same size, and I can turn for one thread, but then it becomes impossible. My suspicion is they might have different size thread. I counted 6 threads in approx 11 mm on the pipe coming from the ground and 5 threads in about 8 mm in the flange on the pipe coming from the dryer. My measurements were crude but these come close to a 14 threads per inch on the pipe coming from the ground and 18 threads per inch in the pipe from the dryer.

What would be some of the ways to connect these two? I can't figure out any adapter from Home Depot or Lowe's website.

Answer 1

Aside of that very rusty pipe might need replacement using two wrenches (one to hold the vale one to unscrew and replace the pipe)

You need an adapter that looks like this.

Source: adapter

Answer 2

This 1/2" flare to 1/2" inch FIP coupler did the job. The dryer is happier than ever.