My recently purchased house has what I think is a galvanized main water line entering into the basement. There is a very uniform bulge in the pipe before it reaches the main water shut off valve. I have two concerns. First, although the bulge appears to be too perfect to be due to freezing, I cannot figure out why the pipe would be intentionally larger for only about 2 inches. This is only about an inch from where it threads into the main shut off valve. Is this a concern?

My second question is how do I replace the main valve as it has a small hole in the side that is weeping water?

Thank you in advance for your help!
Mike

Show us a picture of the pipe and the valve. A galvanized pipe would not bulge.