Does this gas range valve need replacing?
If you're concerned that the valve is ok, call your local gas company. They'll come out to re-light pilots, and will also come out if you have any questions about something you're doing with any gas lines. 

They really don't want you to have any problems. They will also do easy simple repairs, but tell you to get a pro to fix something bigger. For example, I called them once about the gas valve to our pool heater was really tight, it seemed to be rusted and I couldn't close it. The gas guy came out, took the nut off the back, pulled it apart and applied some grease and it was like new. It was apart for only about 20 seconds and he didn't even shut off the gas! He also checked the heater that it was working ok.