# LPG plumbing - teflon tape?



## MarkSF (Feb 21, 2011)

The day is nearly here to re-commission the LPG system. 

I have new tanks that aren't rusted out, a new Trident regulator with pressure gauges for leak checking, the locker has been painted inside with bilgekote, and I have a new solenoid valve / leak detector unit. 

The valve will go in the locker just after the regulator, and the leak detector sensor will go in the bilge.

There's an existing pre-made hose to the locker which I'm going to re-use.

So all I need to do is fit the solenoid valve to the regulator, and the hose to the valve. Is teflon tape still the thing? I ask because I've heard of better liquid sealants that set.


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## zboss (Mar 26, 2006)

Use pipe dope for a permanent attachment and tape for semi-permanent.

Oh... also... if you use tape be sure to use the higher double thickness grade (yellow not white tape).


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## MarkSF (Feb 21, 2011)

I looked at Loctite and they do 561 and 567, both are semi-setting compounds (can be dismantled again) that are claimed to replace tape and are approved for LPG use up to 150PSI. Should be fine for my low pressure side?

Has anyone used them?


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## hellosailor (Apr 11, 2006)

Mark, I think you'd be fine either way. With teflon tape ust don't wrap the very end of the thread, so no tape slivers get sliced off and go downstream into the regulator or jets. With LocTite, you probably have to degrease the threads for best results, and of course it actually has a shelf life--you'll throw out most of the bottle two(?) years from now, or it won't seal properly.

But either one will work.


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## overbored (Oct 8, 2010)

567 best stuff. good for years in the tube. I use it a lot. better then tape. can be undone. small tube is about $5 can be used for all plumbing on the boat even diesel.


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## JohnRPollard (Mar 26, 2007)

Hi Mark,

Sounds like a good project you've got going there -- nice upgrade!

The answer to your question depends in part on what kind of fittings you are using. Many of the connections now used in propane systems have flanges that are sealed by compression or o-rings. In those cases, it's not necessary to use tape or other. 

If compression flanges or o-rings are absent, and it's just threads doing the connecting, I've had very good luck with standard teflon tape. Make sure to wrap it in the same direction that the threads will be turned in. Otherwise, it will bind up as you screw the two pieces together. Also, be careful to make sure the tape doesn't make a flap over the opening of the hose -- I once spent a few hours troubleshooting a lack of flow through only to discover the tape was blocking the orifice.

Remember to always pressure test the system after making these connections, and on a regular basis throughout the season. Good luck!


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## deniseO30 (Nov 27, 2006)

Just a note about pipe threads, "NPT" The dope or tape helps fill microscopic gaps on the edges and valleys of the thread, NPT threads are tapered, the more you tighten the tighter they get, EXCEPT, you can go too far and stretch the receiving fitting, or split it (rare occurrence) If you have ever seen old dies cut threads (My dad was cheap sob plumber) the threads will be ragged, near impossible to seal, if you buy pipe nipples make sure the threads are smooth if they feel rough, don't use them.


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## funjohnson (Aug 20, 2008)

When I was switching over the LPG, I was given a tube of Permatex 2A gasket by the supplier of the new stove orifices.


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## ScallywagSailor (Mar 14, 2015)

Hi all! I want to revive this old thread to ask a related question:

We just upgraded our boat’s stove and are just undertaking the process of replacing old parts in our LPG system. A few questions specific to this thread: 

• I’ve seen a lot of people recommending Permatex over Teflon Tape, but does anyone know the specific type of Permatex we should use for sealing the threads in an LPG system?

• We connected a new stove yesterday and just used Boat Life / Life Caulk to seal the threads between the hose and the stove. Was this bad? Should we remove and replace with a proper thread sealer?

Thanks so much all for your mindtrust!


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## Capt Len (Oct 9, 2011)

Bad


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## pdqaltair (Nov 14, 2008)

ScallywagSailor said:


> Hi all! I want to revive this old thread to ask a related question:
> 
> We just upgraded our boat's stove and are just undertaking the process of replacing old parts in our LPG system. A few questions specific to this thread:
> 
> ...


a. If you used Boat Life Caulk, I advise you stop with all plumbing projects until you do some reading, preferably not just on-line inquiries. There are other code and practical issues you need to understand.

b. The condition and fit of the threads is far more important than the specific sealant choice (assuming it is an appropriate sealant). Most leaks are traceable to poor fit and mis-matched threads rather than poor sealant.


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## XSrcing (Aug 22, 2015)

Replace that immediately.


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## hellosailor (Apr 11, 2006)

I suspect that if you call the makers and check the codes...Boat Life may tell you their product is not compatible, at best being untested for that use. Permatex will tell you if they have any product designed for it. And even with Teflon tape, there is a specific grade to be used, not just anything.

Being "up to code" generally doesn't bother me, but with potential insurance issues and explosions...you really want to have gas plumbing that you can bet your life on. Not just now, but in five or ten years down the line, too.


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## mitiempo (Sep 19, 2008)

For Lpg connections you should use yellow teflon tape - not white. This is on any fitting that is not flared. Flared fittings do not use thread sealant at all.

This is what a surveyor will look for.


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## albrazzi (Oct 15, 2014)

Tape is fine pretty much everywhere, follow the recommendations on application direction and you're good with 2-3 wraps on small fittings and since the bigger stuff 3/4 and up have more penetration you will use more but no need to get carried away.all the fittings you use are machined so threads are smooth. Don't let the tape overhang the ends, technical recommendations ask that you stay away from the first thread.One big job of thread sealant is lubrication so the tapered threads will deform slightly as they seal. Teflon comes in many grades the regular white stuff is OK for most any applications then there are others Grey for SS and there are others but they get expensive. There are recommendations on Hydraulic systems to not use Teflon, it can get caught in spool valves. So with few exceptions it perfectly acceptable everywhere. The above specific recommendations are good if you want a soft dope use one someone has a preference for. Be sure its oil resistant and you can use it everywhere.
I'm in the Gas, Oil, Hydraulic business and as Denise said there are many variables on the big field cut stuff but you're not going to see these things on your boat. I use the 567 in the $50 tubes and I know its good stuff if your seacocks are bigger be careful it can be a bit harder to remove on bigger pipe. Its anaerobic, cures after applied in the absence of oxygen.


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## RichH (Jul 10, 2000)

VERY BAD IDEA!!!!!! Doesnt meet ABYC nor NFPA codes!!!!!

*For potentially explosive gas connections, use only the PTFE tape that is supplied on a YELLOW spool - nothing else. *

Such connections should ONLY be made using Teflon tape ... YELLOW Teflon tape - especially made for 'gas' fittings. This PTFE 'yellow' tape is white, the 'identifier' is the YELLOW plastic spool that its supplied on. 
The 'yellow' tape has a very different 'density' than the 'blue' tape and the 'yellow' variety is impermeable to most gases.


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## albrazzi (Oct 15, 2014)

RichH said:


> VERY BAD IDEA!!!!!! Doesnt meet ABYC nor NFPA codes!!!!!
> 
> *For potentially explosive gas connections, use only the PTFE tape that is supplied on a YELLOW spool - nothing else. *
> 
> ...


I stand corrected, on the Yellow tape at least. My experience is in Gasoline and we use special products and systems.
Thanks Rich for clearing this up.


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## Maine Sail (Jan 6, 2003)

I agree with Rich nothing about using a marine sealant even comes close to meeting any safety standard land or water based.

That said I prefer pipe dopes as do most professional gas fitters. If you use a Teflon tape then it ideally should to be yellow "double density" but there is NOTHING in any codes land or water based that requires one to use Teflon tape over dope. For example NFPA 54 allows the use of either a tape or dope provided it is resistant to the effects of the gas being used.

*"Thread joint compounds shall be resistant to the action of liquefied petroleum gas or to any other chemical constituents of the gases to be conducted through the piping."*

The reason for using yellow is that many inspectors are flagging anything not yellow because yellow has been UL tested for gas. There are white tapes that work and have been tested for gas but on land they often get flagged by inspectors because there are so many tapes that have not been tested.

There are plenty of pipe does out there certified for LPG, natural gas and numerous other compounds. The NFPA, AGA etc. codes specify that a dope must be compatible with LPG for it to be used. Both Teflon tape (preferably yellow) and most any professional grade pipe dope will be LPG compatible.

I use* Herculese Real-Tuff* as my main go to pipe dope. My entire hydronic heating system was done with Real-Tuff as well as many, many, many hundreds of marine NPT to NPT fittings over the years.

Lots of professional gas fitters use Gasoila & I have used it but I find it extremely messy. Rector Seal #5 is also very popular among professional gas fitters but has limited uses with some plastics so I keep coming back to Real-Tuff which has great specs and works really well..


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## misfits (Dec 9, 2011)

The purpose behind Teflon tape is to "lubricate" the threads as you make up the fitting(s), not seal the fitting.
Although allowed by code the downside to using Teflon tape on gas, as you make up the fittings it breaks into small pieces in the valley of the threads & has the potential to plug up gas valves. On a boat seeing how the connection to the appliance typically would not have a drip leg to catch this debris, I would recommend using a good pipe dope. 

I teach plumbing & NFPA gas courses for apprentices, yellow spool Teflon tape only on gas vs. blue spool. Can't say I've ever heard that one before, which NFPA code are we referring to 58?


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## mitiempo (Sep 19, 2008)

misfits said:


> On a boat seeing how the connection to the appliance typically would not have a drip leg to catch this debris, I would recommend using a good pipe dope.


Any marine lpg appliance I have seen uses a flare fitting. No thread sealant of any kind is used on flare fittings.


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## Maine Sail (Jan 6, 2003)

mitiempo said:


> Any marine lpg appliance I have seen uses a flare fitting. No thread sealant of any kind is used on flare fittings.


You are correct that the flare fittings don't get any dope or tape but do check at the tank, solenoid & pressure gauge you will see plenty of NPT to NPT. Even inside the range dope is used at the factory and the valve on the propane tank is also sealed with pipe dope..

The flare fittings are on the annealed copper or LPG UL rated hose but the other connections in the system are NPT to NPT....


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## Capt Len (Oct 9, 2011)

While we are on flare fittings,how about the joys of fissures and work harding due to over tightening or vibration. (and the need for annealing) Just the old shop teacher in me.


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## albrazzi (Oct 15, 2014)

mitiempo said:


> Any marine lpg appliance I have seen uses a flare fitting. No thread sealant of any kind is used on flare fittings.


True, flare connections are mechanical and require no thread compound. Its the solenoid valves that typically don't come with flared connections already attached so there are things that needs to be dealt with. If it were just a factory flare to flare hose assembly this question wouldn't exist.

Lost the train there for a while Maine had already covered this point.


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## albrazzi (Oct 15, 2014)

Capt Len said:


> While we are on flare fittings,how about the joys of fissures and work harding due to over tightening or vibration. (and the need for annealing) Just the old shop teacher in me.


Sure any connection mechanical or taper has life issues. Careful inspection is always recommended. Its a good point.


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## albrazzi (Oct 15, 2014)

misfits said:


> The purpose behind Teflon tape is to "lubricate" the threads as you make up the fitting(s), not seal the fitting.
> 
> I would submit its a little bit of both. I have used the wrong stuff on HP hydraulic connections, stuff that worked before a "reformulation" of some sort that lubricated just fine but wouldn't "seal" after a time because of an incompatibility of some sort in the formulation in an application for a fluid.
> 
> That's why I'm swift to defer to a particular tape, one may lubricate just fine and seal but not hold up in service.


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## misfits (Dec 9, 2011)

I never said to use pipe dope or Teflon tape on a flare fitting. As others have mentioned, you do not pipe dope flare fittings, only the male threaded end. If you look at a gas fired appliance in you home there's a drip tee at the appliance connection. That's where all the impurities, dirt/condensation go rather than being delivered into the gas train. That's why I would discourage the use of tape on a boat, there's no drip tee at any of the appliance connections. 

I've never seen or come across yellow spooled Teflon tape. When Mitiempo first brought that up I just figured it was a Canadian Standard. Maybe there's another standard out there that does recommend it but I'm not aware of it. 

Compatibility, that's true of any pipe fitting project. The pipe, fittings, sealing compound, etc. needs to be compatible with the fluid or gas that's being conveyed. One thing we can all agree on, Life Caulk is not a suitable pipe sealing compound


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## mitiempo (Sep 19, 2008)

misfits said:


> I never said to use pipe dope or Teflon tape on a flare fitting. As others have mentioned, you do not pipe dope flare fittings, only the male threaded end. If you look at a gas fired appliance in you home there's a drip tee at the appliance connection. That's where all the impurities, dirt/condensation go rather than being delivered into the gas train. That's why I would discourage the use of tape on a boat, there's no drip tee at any of the appliance connections.
> 
> I've never seen or come across yellow spooled Teflon tape. When Mitiempo first brought that up I just figured it was a Canadian Standard. Maybe there's another standard out there that does recommend it but I'm not aware of it.
> 
> Compatibility, that's true of any pipe fitting project. The pipe, fittings, sealing compound, etc. needs to be compatible with the fluid or gas that's being conveyed. One thing we can all agree on, Life Caulk is not a suitable pipe sealing compound


You do not tape or pipe dope either connection of a flare fitting, only NPT and NPS threads.

As far as I know yellow teflon tape is a standard in both Canada and the US. It is pretty commonly available. Here if a surveyor sees white teflon tape on either propane or engine fuel fittings it is flagged.


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## Capt Len (Oct 9, 2011)

Seems there's two ways to wrap the tape. I wrap clockwise looking at the end of the male fitting .the tape doesn't bunch up as it meets the female thread. Either agree or tell me I'm wrong. A learning situation.


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## mitiempo (Sep 19, 2008)

Capt Len said:


> Seems there's two ways to wrap the tape. I wrap clockwise looking at the end of the male fitting .the tape doesn't bunch up as it meets the female thread.


That's correct Len. The other way it tries to unwrap as you thread it in.


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## hellosailor (Apr 11, 2006)

These are supposed to be the US ANSI standards for Teflon tapes:

White tape is single density and intended for water pipes of 3/8 of an inch or less. It can sometimes be found in a silver color to match the pipes.

Red tape is triple density, for pipes one-half inch to 2 inches in diameter. It is designed for pipes with larger joints, such as water distribution pipes. _Note that the container is red, but the tape itself looks pink._

Yellow tape is double density, and designed for gas and fuel lines.

Green tape is grease and oil free, and designed for pipes carrying oxygen.

Note that they refer to the tape, not the spool, being colored. And colored tapes are actually available out there.

Would two layers of "single weight" white tape perform the same as one layer of yellow tape? Probably. But code is code, and tape is cheap in the long run.

Oatey 31403 Yellow GAS/TFE Tape, Dispenser Pack, 1/2-Inch x 260-Inch
by Oatey $5.25 Amazon Prime

Five dollars for a lifetime supply of the right stuff expressed from what isn't the cheapest source. Versus, fifty grand for a boat? And a much stiffer price in the burn ward?

But if you really wanted secure connections, wouldn't you want to overseal all of them with a nice heavy epoxy permanent seal as well? (WEG)


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## capta (Jun 27, 2011)

For fuel line fittings I've always used Indian Head shellac (for gas, but works great on diesel, too) on the threads and I have NEVER had a leak (air or fuel). It does not hinder disassembly and can be cleaned up with a bit of wire brushing for reassembly.


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## ScallywagSailor (Mar 14, 2015)

Thanks so much everyone for the advice! It is hugely appreciated. Your shared knowledge has very effectively prevented us from blowing ourselves up, which is really the best thing Sailnet can do, right?

We have confirmed that the stove has a 3/8" flared connection, so we are going to remove the Life Caulk altogether, clean the threads and reattach confirming that it is connected with a 10mm forged flared hose to the main propane line (we have a gimbaled stove, hence the hose). 

We are planning to clean the threads using a wire brush and solvent then wash with soap and water before reattaching. Anything we should specifically watch out for there?

At the point of the Propane locker, we are replacing old equipment with the following in order from the tank:

1) Trident Marine 1200-1411 Kit Assembly: Includes POL Tank Fitting to a 300 PSI Gauge to a L.P. Gas Regulator (Comes fully assembled and leak tested)

2) Trident Marine 1300-7761-Kit 12VDC L.P. Gas Control & Detection System Kit: 3/8" Solenoid to be installed after the regulator with an on/off switch in the galley along with vapor detectors near the locker and under the stove.

The Solenoid is for sure 3/8" FPT ports and not flared, so we are planning (based on this discussion) to connect those using Yellow PTFE Teflon Tape. 

We will inspect the locker for air tightness, as well as any connections using a soapy water spray bottle.

What do you all think? Thanks again, for all your help.


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## mitiempo (Sep 19, 2008)

The only thing I will add is to replace the line from the locker to the stove with a propane approved flex hose with the only connections being at the stove and in the locker.


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## misfits (Dec 9, 2011)

mitiempo said:


> You do not tape or pipe dope either connection of a flare fitting, only NPT and NPS threads.
> 
> As far as I know yellow teflon tape is a standard in both Canada and the US. It is pretty commonly available. Here if a surveyor sees white teflon tape on either propane or engine fuel fittings it is flagged.


I think we're saying the same just in different ways Brian. When I say male end, it's the npt side of the fitting. I also now understand why the reference to "yellow" tape after vising Oatey's web site. Evidently they make tape products geared for specific applications. 
If one was to use an Oatey tape for "gas", the yellow tape would be the proper product to use.

Although now sold by Oatey, the Hercules brand is what's sold in the plumbing wholesale houses in my part of the world & is used by tradesman on everything including gas because it's for universal applications. That's why I had a what in the world are these guys talking about moment when the "yellow" tape was brought up.

That's all.


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## IStream (Dec 15, 2013)

You don't want an airtight locker, you want it to drain overboard. Alll other potential gas egress routes need to be sealed but there must be a drain.


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