Installing union in gas line

When installing a gas union do you put any type of thread sealant on the union threads or mating surfaces when connecting it or do you do it "dry"?

I'm talking about the union joint itself and not the threaded joints where the 2 union pieces connect to the 2 pipes to be joined. Those would get sealant off course.

Thanks,

Absolutely not. Those unions are designed to be ground joints and do not require sealant of any type.

However I've seen many a do it to stop a leak, replacement is the correct repair.

Might want to use a little oil on the threads to help make up the joint but the actual faces do not get any pipe dope etc....
Where is the union being used? (location in piping system and in house?)

I use some teflon dope on the male threads only, then wipe the mating faces clean. The reason is to keep the threads from siezing, but not to mess with the machined faces. I figure they're machined for a reason... Also, all the black pipe unions I use have a copper insert; i guess that forms a malleable seal...

And, yes, I do a similar thing on flare fittings... (except for 3/8" and smaller)

markts30 said:

Might want to use a little oil on the threads to help make up the joint but the actual faces do not get any pipe dope etc....
Where is the union being used? (location in piping system and in house?)

Click to expand...

The union will be installed on the way to a gas stove. There is an existing plugged T off the hot water heater that I had installed in anticipation of the future stove.

I'll unplug the T go into shutoff valve then union then a 90 up to vertical and a 90 to horizontal across into a T with drip leg down and 5" nipple up through floor to another shutoffvalve with flare adapter for flexible gas line to stove.

(of course there are nipples of various lengths between all of these joints. total distance of new add on run is about 2 feet)

I wanted the 2 shut off valves so that if I ever (hope not) have a leak problem with the stove I can run downstairs and quickly shutoff instead of having to wrestle with the stove or dig under it to shut off.

The union will make it easy to get everything up into place as I'm pretty tight agaist the wall with the T and the vertical up to stove/down to drip leg.

Sound OK?

Thanks,