Installing a union between an existing elbow and t.

[Ralph Vart]

Hello Members,
I need to install a union between an existing elbow and a T on a 3/4 inch residential gas line. I'm not sure it can be done, but thought I would ask for your advice.

The photo I pasted below shows the set up. I want to install a union on the horizontal 5" nipple painted tan that runs between the 90 degree elbow and the T. I'll explain why later, but I need to disassemble the fittings all the way to the 1.25" vertical pipe painted grey (the one with the valve on it).

I don't think I can take apart any of these pipes, since they are locked in place. Somewhere along the line, plumbers decided to add stuff without putting in a union. My idea is to cut the 5" nipple and put the union between two smaller nipples, probably a 2" and a 2.5"

I foresee two problems. The two nipples and union are going to need some play to fit together, but there isn't any. (if you are thinking there is some way to disconnect the pipe traveling to the right, there isn't. It hits an elbow and goes through the wall.) How do I deal with that? And it looks like nipples come in only half inch increments, so what happens (even if I can get them all threaded) if I need less or more than that? Can they be custom made? Can I get a chisel and knock away from stucco and get a half inch of play that would allow me to get the union in place?

As for the reason I am doing this, that vertical 1.25" pipe is a long gas line to a pool heater. It was leaking underground and replaced in two areas. That was great. It held pressure. But the plumbers never blew the lines clean. As a result, the heater was not getting enough gas to ignite. I was able to clear a blockage right at the valve going into the heater and it did ignite. But I am sure there is more debris in the pipe that could clog up again or worse clog the gas valve on the heater. So, my idea is to disassemble the ends of the pipe near the meter and near the heater and blow the lines with compressed air. Yes, the plumber who did the repair to the pipes should have done this, but he's out of the picture now.

 

[Fitter30]

The problem isn't the fitting but nipples might have to be custom cut and hardware stores are not equipped. Stainless steel flex pipe approved for exterior. Probably have to remove the 90° (ell) wall tee redope what ever come loose and reposition. Since the flex lines tend to be smaller in diameter might want to consider 3/4" bell reducer and nipples to increase pipe size to 1" for 1" flex that has 3/4" line.
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[Ralph Vart]

Thanks Fitter30. Let me ask about a different approach. If I start at the meter, remove the seismic shutoff and remove the vertical nipple, could I rotate that T and remove it? Or would it want to push the nipples on both sides outward?

 

[wwhitney]

What type of underground gas pipe is that after the valve, and is it perchance a type that could be disassembled similar to how a union can be? And what is that fitting between the valve and the tan reducing tee above it? I mean, when that underground pipe was installed, presumably it was effectively connected between the fixed points of the ground and the tan reducing tee, so I would think it have been done in a reversible way.

Anyway, as to your question, if you cut out and remove the horizontal nipple between the tan straight tee and the elbow, the elbow will now be free to spin, so you can remove the elbow. In theory you could then reinstall the elbow along with two nipples and a union, by installing the elbow first, but slightly less tight (5 or 10 degrees) than it is now; then a nipple and union half into each of the elbow and the tee; and then tighten the elbow the last few degrees to align the two union halves.

I think that would still require a little bit of left/right play in the system to let the two halves of the union slide past each other to be aligned; I forget the exact geometry of the unions faces. And of course it would still require that you get one of the two nipples an exactly precise length.

Cheers, Wayne

 

[Ralph Vart]

Wayne,
I don't think if you attach a nipple and half a union on the elbow, it will not turn because it will hit the wall. As for the pipe past the valve, it is under a long stretch of concrete. Perhaps the only approach is to get a plumber out and cut out all the press fittings and on the vertical part of the pipe going into the ground and install a union with a new valve. But the cost of that probably isn't worth the benefit. I am only theorizing that there is more dirt in the pipe and that it will clog the pool heater.

 

[wwhitney]

I don't think if you attach a nipple and half a union on the elbow, it will not turn because it will hit the wall

If you read my proposal again, 99% of the elbow rotation occurs without the nipple and half-union in place. You all but fully tighten the elbow first, then install the nipple and half-union, and then tighten the elbow the final fraction of a turn to align the two nipples and union halves.

This assumes that the clear space between the horizontal tan-painted pipe and the wall is at least one union body diameter wide.

Cheers, Wayne

 

[Fitter30]

Thanks Fitter30. Let me ask about a different approach. If I start at the meter, remove the seismic shutoff and remove the vertical nipple, could I rotate that T and remove it? Or would it want to push the nipples on both sides outward?

From the tee use a 90° face down with like close nipple. The other tee face the existing 90° the other way face another 90° face down with a 2" or longer nipple. Then use the 3/4" x 1" bell reducers and use a 1" flex and it will hidden behind the meter just bend it like a U.

 

[Ralph Vart]

Now I understand what you are advising. Thanks very much for your help. You're right that the nipples will have to be close to exactly the right length.