LP Flare Fitting, dope/tape

[mikec557]

Well, I'm having to install a temporary propane regulator because mine is among the defective recall. And of course, proper ones are not to be found. And we're on a trip where we don't stay long enough for a slow shipment to reach us.

My only goal is to run the fridge on propane during travel days and maybe one or two evenings of boondocking at state visitor centers. So I don't need 210,000 BTU throughput.

I bought a regulator at Lowe's. BTU is unspecified but a reviewer said it ran his 68k btu space heater. The hose on it, plus a 5ft extension hose (only needed 3ft but couldn't find one) leaves me making a connection to the RV. Both the camper and hose are 1/2 flare male. After checking 4 stores in two cities, no one had a 1/2 flare union. Everyone had tons of 3/8 & 5/8 flare union, but no 1/2.

Finally ordered 3 on Amazon, 2 arrived today. A few reviewers said they got defective ones and I don't have time for that.

But finally to my question. Oddly, they came with some Teflon tape. Ignoring the fact that it's the wrong kind for flammable gas, I recall being taught to NOT use tape on a flared fitting because it could cause the two surfaces to not properly meet up and seal.

I don't think it would hurt to use the paste/dope, but I am a little unsure on that. I have both the yellow Teflon tape and the yellow pipe dope (both are for flammable gas).

Am I right to NOT use the Teflon tape on the flared connection?

[chuckster57]

Do not use any sealant on a flare fitting. Put it together and you can test for leaks using soapy water.

[mikec557]

Originally Posted by chuckster57

Do not use any sealant on a flare fitting. Put it together and you can test for leaks using soapy water.

Thanks. I'll put it together tomorrow and test with soapy water.

[nuctrooper]

Be sure to check the fitting. The inputs to the regulator may have a flare fittings (no Teflon), but the outlet (on mine anyway) is an NPT fitting (which should use tape/sealant).

[travelin texans]

Originally Posted by nuctrooper

Be sure to check the fitting. The inputs to the regulator may have a flare fittings (no Teflon), but the outlet (on mine anyway) is an NPT fitting (which should use tape/sealant).

You beat me to it!
Flare fittings NO TAPE/DOPE, NPT threads YES use the yellow tape/dope.

[mikec557]

Thanks guys. I'm sitting here with a head cold that's killing me. But I'm going outside to connect everything later today.

So, working from a depleted brain, I recall the following: yes, oem regulator is 3/8 female pipe thread. The oem 5ft hose had yellow pipe dope. I wanted to reuse the hose. That would have made this job much easier. But. There's no room for a wrench between the reg body and the hose fitting compressing the brass bit to the rubber hose. That crimp bulges. The hex nut of that bit is barely 1/8 tall. That necessitates a THIN open end wrench, which I don't have and couldn't buy. It mics at .671in which is about 17.5mm. So I'm guessing a thin 18mm open end wrench. But it doesn't matter. I don't have it.

Thus I bought a regulator with a 20in whip of hose crimped on to it. It's a 90-degree setup so the black plastic tank cover can still easily slide over the tanks.

The end of the reg whip and 5ft hose extension are both 3/8 female flare. It was easy to find a male union for those two ends.

It was the 1/2in female union for the other end of the 5ft hose and the camper that was impossible to find. But a two pack from Amazon arrived last night and they both look good.

So for my temporary fix I think I'm flare fittings all the way. Thanks to everyone for your help.

[mikec557]

Okay. This head cold really sucks. As it happens my recall was incorrect. The end of the 5ft hose has a 3/8 NPT. So I did have to dope two connections to get to a 1/2 male flare, so I could use the 1/2in female flare union. By the time I was done outside I was (even more) tired and cold. I'll soap test all of it tomorrow.

[mikec557]

The 90-deg regulator.

[chuckster57]

Stay warm, glad your getting it.

[lunge motorsport]

In regards to the dope or no dope question


Applications on flare fittings vary considerably, take brake lines for example. It is a flare, several types are specified depending on the manufacturer and the country of origin. But it is a high pressure closed system with very little fluid movement. Then there are flare connections like the OP is speaking about which is very low pressure and consumable flow. In the former, I would not use anything but brake fluid as an assembly lube. When I hand form brake lines, I dip the tubing that is going to be formed in brake fluid and then rotate the die several times during forming to make a uniform flare. I then, upon assembly, put a drop of brake fluid on the nut as assembly lube. This method has proved successful over many decades of assemblies. On a flare fitting used in very low pressure gas delivery and appliances, I use non hardening pipe dope on the thread portion and very little on the flare seat. I am very careful to keep the dope away from the bore area because in a low pressure system, any occlusion on the bore diameter can restrict flow and be carried into the operating valve of the appliance causing a malfunction. The seat area on a machined or a hand flare is imperfect at best and benefits from some “assembly lube”. I have repaired many over tightened flare connections that had no type of dope on the flare seat.
So, in short, after over forty years of practical experience and thousands of flare connection installations, I disagree with the consensus on this forum.
Be aware of the compatibility of your dope with the fluid or gas you are transporting!

[mikec557]

Originally Posted by lunge motorsport

In regards to the dope or no dope question...

Applications on flare fittings vary considerably,..

So, in short, after over forty years of practical experience and thousands of flare connection installations, I disagree with the consensus on this forum.
Be aware of the compatibility of your dope with the fluid or gas you are transporting!

Looks like I lost my answer so I'll shorten and it send.

Thanks for your insight and thanks to everyone for your combined input.

I soap tested today. Out of 6 connections (2xNPT, 4xFlare) 1 had a small leak. In the struggle to tighten it and cause and fix a 2nd leak (both on the 1/2in female flare union) I thought if I had doped the last 1/3 or so of threads (furthest from the flare connection) it probably would have prevented the leak. We have about 1000 miles yet to go. I'll keep an eye on the union. If it leaks again I'll try some yellow dope on the last 1/3 of threads.

Again, thanks to everyone.

[flybouy]

I've never put sealent on a flair fitting and never had a leak. I've always used quality fittings and have made many a high pressure fitting connection on refridgerant, hydraulic and steam lines. Only used never sieze on the steam fittings and jo "lubricants" anywhere. I've made my share of brake lines but always made a "double flare" on them.

[mikec557]

Originally Posted by flybouy

... I've always used quality fittings and have made many a high pressure fitting connection on...

This might actually be my issue. No stores I stopped at had any 1/2in female flare union, and I couldn't work out a way to not need one. This left me with what I could get on Amazon and with short delivery time window. There were both good and bad reviews, which means what I receive is just luck of the draw. Maybe when I get home and find the proper regulator I'll find a hose that doesn't need the use of a union.

[chuckster57]

LP uses single flare fittings, brake lines for example use double flare fittings, big difference IMO.

I too have made many LP and brake lines over the years and still stand by my statement, no sealant on a flare fitting. Haven’t had a leak yet.

[rjniles]

Originally Posted by mikec557

The 90-deg regulator.

That regulator is a single stage intended for grills and the like. A RV requires a 2 stage regulator. The issue is it does not regulate well enough to satisfy need the requirements of a propane frig.

[mikec557]

Originally Posted by rjniles

That regulator is a single stage intended for grills and the like. A RV requires a 2 stage regulator. The issue is it does not regulate well enough to satisfy need the requirements of a propane frig.

Yes, it is not ideal. But it works adequately well to keep the refrigerator running. The fridge is not a high demand appliance like the furnace. In fact, my Weber BBQ demands significantly more flow than the refrigerator, and it is content with this same style regulator.

When we get home I will find the appropriate 2-stage regulator. But given the recall of over 80,000 defective regulators, the proper replacement regulators are now hard to find.

[skunked again]

Glad you got it "fixed" ! Hope that head cold gets better !! I've heard, wink wink, peppermint schnapps helps !!

[mikec557]

Originally Posted by skunked again

Glad you got it "fixed" ! Hope that head cold gets better !! I've heard, wink wink, peppermint schnapps helps !!

Dear Dr Skunked

I like the way you think!

Signed
A new patient

[travelin texans]

Originally Posted by skunked again

Glad you got it "fixed" ! Hope that head cold gets better !! I've heard, wink wink, peppermint schnapps helps !!

I prefer cinnamon schnapps over the peppermint, but after a couple prescribed doses I don't really care which flavor.

[flybouy]

Schnapps-root beer, cold remedy call a doctor, calling Doctor Daniels, calling Doctor Jack Daniels!