What kind of valve?

[enantiomer2000]

I noticed this valve on the outside of my house is leaking. I tried turning it further and it never tightens down. This is on the outside of my house in front of my kitchen. What kind of valve is this and can an amateur do this for himself? Please see attachment.

 

[frodo]

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[Mr_David]

If the if the hand turns continuously with out stopping it is broken.
That is a gate valve. the thread on the stem deteriorate and fail over time.
That valve is buried in some stucco/spray coating and will not be easy to replace. Even for a pro. If toy have other means to shut off the system like at the meter than use that and don't touch that valve ever again unless it starts leaking.

 

[enantiomer2000]

Thanks for the advise. I tightened the nut and that did the trick.