Joe J wrote:
We bought a used gas dryer and it came with a flex gas line. Hooked
everything up and we smelled gas. Called the gas company and they
came out and identified the problem as a leak in middle of the flex
line. While there, he had his sniffer out and said we had a slight
leak on the water heater gas supply line. He put some wrap on it and
said it would be fine until it was tightened up.
I'm stumped how to do that. ½ black pipe runs down to a T and the
leak is in the center of the T that supplies gas to the water heater.
There is a shutoff and union in the line. Other side of the T drops
down with a 3" nipple and is capped. There is about a 6" run from
the center of the T to the water heater.
If I open the union and begin to tighten the line into the T, at the
same time I'm tightening at the T, I'll be loosening the line that
runs to the water heater. If I try and rotate the T, I'll be
rotating it away from the supply line and it won't reconnect, unless
I managed to get 1 full turn more.
The gas company guy said it just needed tightening. I'm thinking that
actually means I need to completely disassemble this from the union
down, clean all the parts up and start over with new pipe dope and
reassemble from the heater back to the union. Or am I missing an
easy fix?

I think it depends on exactly where the leak is.

When you say the leak is in the center of the T, do you mean the leak is
where the threads of the T meet the short horizontal pipe that goes to the
hot water heater?

If so, I would say to do this:

1) Shut off the valve.

2) Loosen and disconnect the Union joint.

3) Loosen and take off the vertical short piece that comes out of the bottom
of the T.

4) Loosen and take off the vertical pipe that comes out of the top of the T.

5) Loosen and take off the T from the short horizontal piece that goes to
the hot water heater.

6) Use gas pipe thread sealant or yellow gas pipe thread sealing tape and
re-attach the T to the short horizontal piece that goes to the hot water
heater.

7) Use gas pipe thread sealant or yellow gas pipe thread sealing tape and
re-attach and tighten the vertical bottom pipe and vertical top pipe.

8) Re-connect and tighten the union.

9) Open the valve.

10) check for leaks by smell and/or soapy water around the joints.

If the leak is where I suggested above, the T probably only needs to be
tightened by 1/2 turn to seal the joint, but it's better to disconnect it
all and re-do the joints with new sealant or tape in my opinion.