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Topic: How tight do you make an inverted flare connection ?

Posted By: sunline1 on 08/23/10 01:05pm

Just replaced the pigtails on my camper, asked questions on another post on this forum.

Having second thoughts about how much you should tighten the inverted flare connection. I never have tightened one.

It seams like while turning (by hand), the pigtail into the 1/4" female inverted flare (fiting adapter), when it stopped, i then put a wrench on it and it didn't turn very far, and it "seamed" tight, I didn't want to force it for fear of damageing it. I probaly turned it with the wrench less than 1/12th of a turn. I then turned on the propane and checked with soapy water and no leaks.

I'm curious as to how "Much" you should tighten it after it stops turning by hand ? Or what is the correct procedure for tightening an inverted flare connection ?

Any info etc. appreciated.

Thanks

Sunline1


Posted By: midnightsadie on 08/23/10 01:51pm

you should have been able to start the threads by hand, four or five turns, then you back up the other side with another wrench, and holding the other steady,and firm ,tighten good and snug turn gas on soap test . IF you only turned it a little and it got tight ? i;d double check make sure its not cross threaded.


Posted By: CamperTech on 08/23/10 01:51pm

General rule of thumb is hand tight plus 1/2 turn.
I've seen written in tech manuals to tighten with a wrench until "snug" and then 1/6 turn. The definition of "snug" is certainly a variable interpretation so we go with hand tight plus one half turn. It's worked here for years!


Happy Campin'



Posted By: mike brez on 08/23/10 02:02pm

Make sure you hold back with another wrench. I would say hand tight then 1/4-1/2 turn. I like to put a thin coat of pipe dope on the male side of the flare were the copper tube goes against the brass also.


1994 Pace Arrow 33L,454,P30
2oo4 ground up ridgid chopper 120rwhp
http://community.webshots.com/user/oneHD


Posted By: CamperTech on 08/23/10 02:34pm

Yeah, well...uhmmmmm......by design, flare fittings work with two opposite flares seating to each other to make the seal. Introducing anything like "pipe dope" teflon tape, or any other thread seal, could defeat the seal by getting between the two flares.
So...don't use anything for additional sealant with flare fittings. That stuff was designed to be used with tappered pipe thread!


Posted By: Cloud Dancer on 08/23/10 02:54pm

With regard to dope or no dope, you first have to understand exactly "what makes the seal". With flares, NO dope.


Willie & Betty Sue
Miko & Sparky
2003 41 ft Dutch Star Diesel Pusher/Spartan
Floorplan 4010
Blazer toad & Ranger bassboat


Posted By: sunline1 on 08/23/10 03:10pm

No it wasn't cross threaded. I turned it easily 4-5 turns by hand. Then put a wrench on the "adapter fiting" to keep it from turning and then used a wrench on the inverted flare to turn what I thought was only about 1/12th of a turn. It didn't leak with the soap test, but I'm now concerned if not tightened enough it might losen up with the vibrations etc from pulling the camper.

Will redo it and go at least the 1/6, or 1/4- 1/2 turn with the wrench as indicated here.

Thanks all

Sunline1


Posted By: Chris Bryant on 08/23/10 04:07pm

It helps to think about what is happening when you tighten a fitting like this- in a regular flair fitting you are slightly flattening the copper flair to seal the joint, but in an inverted flair fitting like you are dealing with, there isn't a lot of give. Once you get it tight, what has to give to tighten it more? On this connection, you have a near solid brass fitting in to another near solid brass fitting, so there really isn't much there which will stretch.
On this, I would honk it down good, check for leaks, and not worry about it.


-- Chris Bryant
My RV Service Blog
The RV.net Blog


Posted By: Gale Hawkins on 08/23/10 04:30pm

CamperTech wrote:

General rule of thumb is hand tight plus 1/2 turn.
I've seen written in tech manuals to tighten with a wrench until "snug" and then 1/6 turn. The definition of "snug" is certainly a variable interpretation so we go with hand tight plus one half turn. It's worked here for years!


2x


Posted By: LarryJM on 08/23/10 04:48pm

Chris Bryant wrote:

It helps to think about what is happening when you tighten a fitting like this- in a regular flair fitting you are slightly flattening the copper flair to seal the joint, but in an inverted flair fitting like you are dealing with, there isn't a lot of give. Once you get it tight, what has to give to tighten it more? On this connection, you have a near solid brass fitting in to another near solid brass fitting, so there really isn't much there which will stretch.
On this, I would honk it down good, check for leaks, and not worry about it.


I think you are confused on the terminology here which is surprising with your background since the inverted flare and double flare are basically one in the same where the seal is formed by seating the male brass flared fitting against the copper tubing with the matching tightening ring. You can see the proper way IMO to do these HERE. If there is copper tubing involved in the connection then it is a 45 deg in all likely hood double/inverted flare union since AN-37 deg fittings are a special class and do use a single flared tube along with a brass sleeve to made the copper to brass connection secure.

I have absolutely no idea what you mean by a a regular flare fitting since I've never heard of that terminology anywhere.

Larry


2001 standard box 7.3L E-350 PSD Van with 4.10 rear and 2007 Holiday Rambler Aluma-Lite 8306S Been RV'ing since 1974.
RAINKAP INSTALL////ETERNABOND INSTALL



Posted By: 427435 on 08/23/10 05:06pm

I don't have a torque or "turn" value (I just tighten based on years of experience). However, I learned something years ago that I do. That is to tighten to where you think it's tight, loosen, and tighten again. That improves chances of getting the double or single flare fittings to be leak-free.


Mark

2000 Itasca Suncruiser 35U on a Ford chassis, 80,000 miles
2003 Ford Explorer toad with Ready Brake supplemental brakes,
Ready Brute tow bar, and Demco base plate.



Posted By: nbounder on 08/23/10 09:46pm

I really enjoy reading Chris B.s responses. Learn something every day, & it comes through loud & clear, so to speak.


Nbounder
KG7DKF


Posted By: Chris Bryant on 08/24/10 07:00am

LarryJM wrote:

Chris Bryant wrote:

It helps to think about what is happening when you tighten a fitting like this- in a regular flair fitting you are slightly flattening the copper flair to seal the joint, but in an inverted flair fitting like you are dealing with, there isn't a lot of give. Once you get it tight, what has to give to tighten it more? On this connection, you have a near solid brass fitting in to another near solid brass fitting, so there really isn't much there which will stretch.
On this, I would honk it down good, check for leaks, and not worry about it.


I think you are confused on the terminology here which is surprising with your background since the inverted flare and double flare are basically one in the same where the seal is formed by seating the male brass flared fitting against the copper tubing with the matching tightening ring. You can see the proper way IMO to do these HERE. If there is copper tubing involved in the connection then it is a 45 deg in all likely hood double/inverted flare union since AN-37 deg fittings are a special class and do use a single flared tube along with a brass sleeve to made the copper to brass connection secure.

I have absolutely no idea what you mean by a a regular flare fitting since I've never heard of that terminology anywhere.

Larry


I wasn't clear- by a regular flare, I mean not an inverted flair- a standard 45° flare (which is still often a double flare) with a flare nut .
My point was really that on these pigtails, both sides of the joint are basically non-compressible solid fittings with machined surfaces, as opposed to having a piece of tubing forming the flare, which is compressible, and will take quite a bit more tightening to properly seal. The inverted flare on the pigtail is a holdover from the days when these pigtails were copper.

All of these flares on RV systems are 45°.


Posted By: hotsparks on 08/24/10 10:05am

Don't confuse "JIC" 37* fittings with "Compression" fittings which are 45*. Or "NPT" which are tapered thread.


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