Risk of cutting galvanized where it enters the crawl space

[ChasB]

I know this may be tough to answer but I'll ask anyway. The only shutoff I have for my water supply is at the street (this is in Renton, Washington). The house was built in 1967 and they did not put a shutoff in the crawl space. I'd like to put one in but the best place for it would be right after it enters the house (see the pic). The water main is the original. Would you experienced plumbers consider it very risky, somewhat risky or not risky at all to saw the line open at that point. My concern is that the vibration from the saws-all and cranking on the pipe could result in a break between the house and the street. FYI on the pic --- the pipe going left is to a bib faucet. The other pipe is a 30 foot long section, so I could cut that long section instead of that first vertical 18-inch section --- maybe that's less risky?

 

[Standardairconditioner]

Nothing you do to those pipes will break apart your concrete. I've used Sawzalls on pipes that were held merely by drywall.

No amount of pipe turning or twisting will loosen anything here, too old, too seized. Things will bend before the seized threads give way.

Your best friend here is a disc grinder, not a Sawzall. A small 4-1/2" grinder with any cheapie cutting disc will do fine.

A grinder is more precise, and better to use if you have the work space. Sawzalls are good to reach into deep closures where a long blade saves you, but the grinder will be more precise and cut exactly where you hold it. That old galvandized is so soft, a grinder will melt thru it.

I know you only want to do the minimal to get a shut-off in there, yet you should plan to replace all of that eventually, so ideally I would put a quality ball-valve somewhere on that vertical. That way in the future, you can also toss all the rest going to your house.

Grinding any pipe to separation is easy. You may choose to grind off the upper elbows and re-use the threads on the top of the vertical to get your ball-valve on it. Grind as deep as you can into the elbows without getting to the threads, a pry bar can be used to widen the cut, snapping it off.

You also have the option to remove the entire vertical and save that bottom elbow, perhaps to get a ball-valve down there, or a new vertical pipe. The grinding technique is similiar, just inverse. Look for videos on how to grind away an inner pipe and its threads, to save an outer fitting.

 

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[CountryBumkin]

If you cut the vertical piece in the middle and can then unscrew the two pieces, you've got it made. Hopefully the pieces will unscrew. I would try soaking the fittings with PB Blaster or similar over a couple of days. If the old pipe doesn't unscrew (as StandardAirCondtioner suggests) its going to be a real pain. This might be a job for a professional.
If your set on doing it yourself, I suggest you have a backup plan (and parts ready) incase this goes bad. It's no fun having the water turned off for the family while you try to find parts.
Good luck.

 

[Standardairconditioner]

Hopefully the pieces will unscrew. I would try soaking the fittings with PB Blaster or similar over a couple of days.

Not going to work. Waste of time. As hopeful as thinking drain cleaner will work on toilet clogs.

We're not in the restoration business to preserve old fittings. Grinder gets rid of them in about 2 minutes. OCD's can do precision grinding with more time, maybe 4 minutes.

For those that don't own a grinder, even a cheapie one from Harbor Freight will do. It'll pay itself off on the first cut.

I use PB all the time, great product. PB is great for automotive because cars are usually under 10 yrs old. Things are different with 50 year old fittings.

 

[Terry]

At some point you will want to run a new water line to the meter. It should be at least 1".
You can cut and then unthread the pipe from those fittings. You would need a union to mate the to sides up again. Anytime you touch galvanized, you run a risk. I remember one time in Medina where I cut a pipe in an old home, guessing it was a vacation cabin at one time as there where no bridges over to Bellevue at that time, and I had to keep chasing good enough pipe to make a good connection. Pipe was just snapping off it was so old.

 

[DougB]

There really shouldn't be any problem with that galvanized - as long as you have a big enough wrench. I've taken apart 75 year old galvanized - penetrating oil really doesn't work on those threads.

I would support the horizontal pipes, use an angle grinder and cut out a section of the vertical pipe, then unscrew each end from the elbows. You could replace the section with copper and a shut off. Outside, where you have more room - make up the new vertical - a pipe to copper sweat adapter, short length of copper, the valve, and another short length of copper - solder it all up. Then use teflon tape and pipe dope and install the valve on the lower elbow. Make up a pipe to copper sweat adapter and a short length of copper - slide a copper coupling - WITHOUT A STOP, over the copper tube. Install on top elbow. Slide the coupling over the joint and solder.

 

[Terry]

Copper to galvanized closes up very quickly. The two dissimilar metals don't like each other and the galvanized side is the side that loses the battle.
https://en.wikipedia.org/wiki/Galvanic_corrosion

I use a 6" brass nipple to transition.

 

[ChasB]

Wow - Thanks for the comments and advice. I started looking harder at this due to a bathroom that I am adding. The annoyance of having to go to the street shutoff over and over to do work is a pain. The house was built in 67 with no mods since then. I was able to remove two pipes down the line using DougB's method (I added shutoffs there so finishing the BR work will be easier). I figured the same method would would work here with the only risk being a break outside the house, but y'all (except DougB) have lowered my level of confidence a little. I do want to change everything over to PEX and was planning on doing that after the BR gets done/approved. Maybe I'll look into getting the meter to the house replaced, then re-evaluate. But I'm still listening if anyone has more to add...

 

[Standardairconditioner]

cut out a section of the vertical pipe, then unscrew each end from the elbows

This is what will happen: as you grip the vertical and try to screw it off the elbow, they don't move, so now you are turning the entire elbow and everything attached to it, putting torque on everything and bending the crap out of it.

The idea is to remove what you want to, without distrubing the rest that you don't want to remove.

Elbows can be grinded and snapped off EASILY and replaced with new ones. It's easier to save male threads on a pipe for re-use, than to save a female elbow.

 

[ChasB]

Got it. I will look for videos and try it on some spare pipe. That's my objective with this --- no disturbance!

 

[DougB]

It's easier to save male threads on a pipe for re-use, than to save a female elbow.

It looks like the lower elbow is dead against the cast iron waste pipe. I'm not sure how you are going to screw a new one on?

I can't believe in 1967 (the year the OP says the home was built) that they used galvanized instead of copper.

 

[ChasB]

Good point. I will have to avoid that. it was built in 67 - just checked again to be sure. I haven't been able to locate a video showing how to grind off an elbow or tee and save the male threaded pipe. Maybe a YouTube opportunity for someone.

 

[Terry]

I normally leave the fitting there, and thread into that. Two pipe wrenches is all I need. That and one cut in the middle.
I also have a hand threader if I cut pipe and need threads on the end.
don't even think about touching the pipe going through the concrete foundation.

 

[Standardairconditioner]

I haven't been able to locate a video showing how to grind off an elbow or tee and save the male threaded pipe.

If you are new at grinding, ALWAYS practice on something else first. You'll get used to how to be safe with it. Never let your first use of a grinder on the repair object.

To grind away an elbow to save male threads on a pipe is easy. Experience tells me to make a cut at the small of the elbow, I wedge a prybar in there, and it loosens away after I widen it, or splits into two. For DIY first timers, you can grind multiple spots, just keep at it until the elbow just loses integrity and eventually succumbs to falling apart.

To grind away a pipe to save the female threads in an elbow or anything else, grind off pipe so that you leave about an inch on it. Then start grinding cuts along the grain of the pipe, and use a chisel to dent the pipe inward, eventually you want to be able to use a Vise-Grip to curl the pipe so that its diameter gets smaller and smaller and eventually it collapses out.

I can do either of the above in about 60 seconds, quicker than it would take for me to fetch a can of PB from my van which I know will not work here.

Parts are inexpensive to replace. Grind out whatever you want to, and replace it with new.

 

[CountryBumkin]

Nice follow up StandardAC.

 

[ChasB]

I second that - great post!