Repacking a live valve

[LikeABigFriedEgg]

The quick question is: can I repack a globe valve without shutting off the valve upstream? Details follow:

Hi. The city's contractor is coming in soon to replace the water meter, and my main indoor shutoff valve is not in great shape.

It leaks through the packing, and so it drips a little. I've tightened the packing a few times, but lately that doesn't do much good. Also it doesn't shut off completely, so a little water leaks past the plug and comes into the lines when the valve is closed.

I want the meter replacement to go off without a hitch. My questions are two:

1) Will the slight leak past the plug cause the contractor any problem swapping meters?

2) Can I repack the valve without closing the city's valve outside and without causing a flood? I think (and hope) the answer is yes, but I haven't been able to find anything about it online.

Thanks for any suggestions and hints to improve the work.

The valve is about 50 years old, and I doubt that it has had any work done on it other than tightening the packing. The water here is very hard, as you might see from the picture ... around 28 gpg. That is 3/4" nominal copper coming up through the floor.

 

[Reach4]

I am not a plumber. What I write below could be mistaken.

1. I think no.

2. If the valve is like the one pictured below, yes. You would close the valve. You would shut down the WH. You would close the WH supply valve to prevent that from providing water. You would bleed off water from pipes, opening your lowest faucet and highest faucet.. You would slowly loosen the packing nut some, watching that the dripping does not increase. You would probably pull the handle to let you lift the handle. You would apply packing cord around the handle.. Some like the white PTFE cord. Some like the black graphite cord. You would tighten the packing nut.

 

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[LikeABigFriedEgg]

Thanks. Not sure why to isolate the water heater. It is also in the basement, and it is supplied by a pipe that is seven feet above the floor. Maybe there is some possibility of a siphon? I hadn't thought of that. But I think that opening the other valves would break the siphon.

 

[Reach4]

I was concerned that the dip tube in the WH could serve as a siphon. There may be a little hole in the dip tube preventing this, but just in case, turning off the valve to the WH is easy.

When I have drained my pipes, I suspected there might be some water coming from the WH.

 

[LikeABigFriedEgg]

Well, the meter change went pretty well. I cleaned up the valve using vinegar and brass brush and water. I exercised the packing nut (loosened and tightened) and the valve stem (opened and closed it), and then finally tightened down the packing nut to where it isn't leaking (or at least not dripping). I guess it looks a little better now, ha ha. I intend to install a ball valve downstream so I won't have to use this valve much anymore. Reach4, thanks for your help.