Sioux Steel has lifetime guarantee gates. They are powder coated. They are guaranteed against any damage that makes them unusable. You can get on there website to find your nearest dealer.
We really like our lynn pipe and post gates. They usually work with you on shipping, order them with the extra bar and heavy duty. We have some we hung over 10 years ago that are still as straight and nice as the day we hung them. http://linnpost.com/Gates.html