Propane systems - sealing threads?

[Harris Snyder]

Hi guys, I just got my first propane burner. gonna try to rig up a propane forge rather than burning charcoal all the time. I've got a regulator that feeds a hose which is connected at the other end to a needle valve, a T for connecting a gauge, and then it goes into the actual burner.

 

My question (I'm new to propane) is do i need to (and how do i) seal the threads on the connections. Can I solder them?

 

Thanks

[Harris Snyder]

Sorry for the double post but it looks like the edit button is gone (?). I also realized that the threads are a bit tight, i would be tempted to put a bit of oil on them to get them to fit all the way together without risking damaging the threads.. Then I'd solder the connections closed. Bad idea?

[Jack Evers]

To me, bad idea. Teflon tape will seal the threads, There is a special heavy yellow for natural gas (propane is similar to natural gas), but the regular white stuff should work. I've used it at a few thousand psi, you're working with a few 10's of psi. Not a big problem. Just use a soap solution to test the joints and have fun. Don't use oil.

[Frosty]

I know my knowledge is several years old and T tape may have been changed or specially made so it's okay. I just don't know and where safety is concerned pretty conservative. I'd make a call, the local heating/plumbing guys are on the ball.

 

Frosty The Lucky.

[Larry H]

use the yellow teflon  its made for petroleum products, the white may melt. Don't use oil near any gauges

[BobL]

I knew about using the the yellow teflon tape from lab renos at work and then walking around the side of our house just the other day I noticed whoever did the gas plumbing used the white stuff. Most people will know about this but just in case, the tape works better if (facing the front end of the thread) you wind it clockwise. If you wind it the other way the winding action tends to draw the tape away from the thread. 

[Harris Snyder]

Right, okay. Everyone seems to be saying tape, so thats the way I'll go. Thanks everyone!

[ptree]

In many localities tape is against code for natural gas or propane. There are many good high quality pipe dopes made for gas or propane, that work better. Note Teflon tape is a lubricant, not a sealant. Tapered threads will almost seal from the taper but on a slippery molecule like natural gas or propane will not reliably seal. In long ago days bar soap was often used to lubricate the threads and allow them to go in deeper to help get the interference fit that would seal(Mostly).

If using teflon tape, most people use way too much and wrap wrong.

To use teflon tape:

hold fitting in right hand, hold tape in left. Place tape  on threads at least 1 full thread on top,away from small end of fitting. Use first finger to hold tape in place abd twist fitting clockwise. Use finger to hold tape in place and stretch tape enough to get it to tightly conform to threads. Continue wrapping until no more than 2 full wraps are made. Hold finger on top of tape on fitting and pull tape to stretch and break.

 

You need to not wrap the first thread or so to prevent bits of tape from being cut loose and getting in the system. These tape bits will stop up a orifice in a burner, another reason for pipe dope.

 

Ptree who worked in the R&D lab at a valve company that made many million pipe threads a month, and who has worked to 33,500 psi. Never found a pipe thread that would seal completly at much over 10,000psi, those were double ferrule tube fittings with the fittings welded in. At pressures above 15,000 used cone and threaded sleeve.