1 Inch Steel Pipe Coupler

My wife wanted to hang curtains around our backyard patio. However, we couldn't find any strong, seemless, weatherproof, metal curtain rods. So, we bought some 1" galvanized steel pipe from Home Depot along with some 1" curtain rod holders (hooks?).

We have a 14 foot section on our patio and the longest pipe we could find was 10 feet. So, I made this little coupler to join two sections of pipe together.

The coupler is designed so that you should be able to twist each pipe on clockwise. Jus