Never seize in lieu of pipe dope

[Glenn Brooks]

giggle.....functioning practice and theory often never intersect

Bill. Well Said! As I find out daily

(BTW, H: the Teflon flame test was not intended as a serious experiment. I mentioned it due to its rather humorous outcome!)

Glenn

[rkcarguy]

I ended up building and connecting our 4,000PSI Oxygen and Nitrogen lines to my workplaces laser installation the year before last. It ended up there was a "gap" in the install scope and the piping guys had already signed off and left, and the machine installers were wondering where the flexible lines were that connected to the machine and we were pretty much ready to fire it up otherwise so the pressure was on (pun intended).
Anyway, everyone said "you have to use the paste it's the best", and despite my prior experiences with it always leaking, I did. Sure enough, 3/4 of the connections leaked like a sieve. I had to take everything apart, clean it all up again (oxygen line had to be surgically clean), and then I applied high temp yellow Teflon tape. You have to be careful to wrap it above the first couple threads, and wind it in the proper direction so it won't turn out little chunks inside when you tighten it up. After that, one fitting leaked slightly, which was fixed with another 1/4 turn on that fitting.
Indeed, direct flame heat is far different from the heat that will radiate into a bolted joint. I have an air cooled go kart engine that has a head temp sensor on the head bolt near the exhaust. While the exhaust is well over 1,000*, I tune my carb so that I keep the head temp under 400*. The gold iridite finish on the head bolt remains, so I don't think it gets that hot and if I needed to seal it I'm sure the high temp Teflon tape would hold up fine.

[Glenn Brooks]

Ryan, one more good data point! I looked on line. This yellow Teflon is a new one to me. Apparently the OTC versions of the tape have a working temp of 500*F. Home Depot carries, or at least sells on line, a white household Verizon, also- same temp rating, 500” roll for $4.43. Thanks for the info.

Glenn

[John Hasler]

I ended up building and connecting our 4,000PSI Oxygen and Nitrogen lines to my workplaces laser installation the year before last. It ended up there was a "gap" in the install scope and the piping guys had already signed off and left, and the machine installers were wondering where the flexible lines were that connected to the machine and we were pretty much ready to fire it up otherwise so the pressure was on (pun intended).
Anyway, everyone said "you have to use the paste it's the best", and despite my prior experiences with it always leaking, I did. Sure enough, 3/4 of the connections leaked like a sieve. I had to take everything apart, clean it all up again (oxygen line had to be surgically clean), and then I applied high temp yellow Teflon tape.

As far as I know only green teflon tape is oxygen rated. I hope the paste was oxygen rated. Most kinds contain oil.

[rkcarguy]

I ended up building and connecting our 4,000PSI Oxygen and Nitrogen lines to my workplaces laser installation the year before last. It ended up there was a "gap" in the install scope and the piping guys had already signed off and left, and the machine installers were wondering where the flexible lines were that connected to the machine and we were pretty much ready to fire it up otherwise so the pressure was on (pun intended).
Anyway, everyone said "you have to use the paste it's the best", and despite my prior experiences with it always leaking, I did. Sure enough, 3/4 of the connections leaked like a sieve. I had to take everything apart, clean it all up again (oxygen line had to be surgically clean), and then I applied high temp yellow Teflon tape.

As far as I know only green teflon tape is oxygen rated. I hope the paste was oxygen rated. Most kinds contain oil.

There is a yellow tape that is oxygen rated (it's dual spec), we actually found a leftover roll in the extra parts box from the pipe crew that installed the balance of the lines. No one had the green stuff locally and the yellow tape that was available at Lowes was not oxygen service rated. I would order the green tape if I needed to do it again. The paste didn't work but it was supposedly formulated for oxygen, I didn't use any of it I had to clean it all off and flush all the lines (again).

[Glenn Brooks]

Greg,

Just started to assemble my front end blast nozzle. Used the graphite pipe dope you sent - man that’s good stuff! Thanks very much for sending it to me . Iam a believer!

Glenn

[Greg_Lewis]

Glad it worked. Messy stuff though.

[reubenT]

Neighbor used to be a mechanic, long ago he experimented with silicone used for auto exhaust system gasket sealer, everything would harden and break up except the super high temp copper. So I end up using that for sealing gaskets and pipe joints, seems to work fine on steam pipe joints as well. And hydraulic fittings, as long as it's allowed time to set up before applying pressure. It will seal minor gaps but if there's too much leakage before the sealer fills the gap it will blow out if pressure is applied before it dries.

[John Hasler]

reubenT writes:
And hydraulic fittings, as long as it's allowed time to set up before applying pressure.

And make sure there is no excess to get into the system.