Sealant for copper flare fittings?

Reply

  #1  
Old 04-01-07, 11:18 PM
Member
Thread Starter
Join Date: Jan 2007
Location: LI, NY
Posts: 62
Received 0 Votes on 0 Posts
Sealant for copper flare fittings?

When connecting a flared copper fuel oil line to a brass union or valve, should I use any kind of sealant on this? I didnt think so, but when I recently took apart some old copper lines from my old tank I noticed that there was some type of hardened sealant on the threads and where the nut contacts the copper pipe on the flare. (20 year old coupling) Is this needed on a new installation?
 
Sponsored Links
  #2  
Old 04-02-07, 04:30 AM
mattison's Avatar
Member
Join Date: Mar 2003
Location: Cinti, OH
Posts: 5,549
Received 0 Votes on 0 Posts
A flared fitting should not need any type of sealant.
 
  #3  
Old 04-02-07, 08:53 AM
Member
Thread Starter
Join Date: Jan 2007
Location: LI, NY
Posts: 62
Received 0 Votes on 0 Posts
Thanks, I didnt think so, but wanted to make sure that it wasnt some "fuel oil only" thing that I didnt know about.
 
  #4  
Old 04-02-07, 09:50 AM
Member
Join Date: Jan 2005
Posts: 207
Received 0 Votes on 0 Posts
I would double flare though, less chance of cracking.
 
  #5  
Old 04-02-07, 10:32 AM
GregH's Avatar
Super Moderator
Join Date: Jan 2001
Location: Manitoba
Posts: 9,987
Received 8 Votes on 8 Posts
Carbuff,
I agree that no sealant is needed.
If a flare does not seal it is usually because the flare has flattened out and needs to be replaced.

The only thing you can do to help a flare is to put a tiny drop of oil where the flare nut contacts the copper flare.
This allows the mating surface between the nut and copper to slide smoothly as it is tightened.
 
  #6  
Old 04-02-07, 10:33 AM
airman.1994's Avatar
Member
Join Date: Dec 2005
Location: VA
Posts: 5,769
Received 4 Votes on 4 Posts
I like to put a little thread sealant on just to help it thread a little easer.
 
  #7  
Old 04-02-07, 12:43 PM
Member
Thread Starter
Join Date: Jan 2007
Location: LI, NY
Posts: 62
Received 0 Votes on 0 Posts
Originally Posted by airman.1994 View Post
I like to put a little thread sealant on just to help it thread a little easer.
That must be what they did. There was this hardened grey stuff on the threads and all over the copper line for an inch after the nut. There was plenty of oil for lube for the new fitting as I had to bleed it at this point. Its all fine now and no leaks. I now have a one big spin on filter in the supply on the wall. I also have the two induvidual filters still for the 2 units (furnace, water heater) on the floor. Do I need them anymore? Do you think I can just remove them and replace them with new solid feed lines? I dont need 3 filters, right?
 
  #8  
Old 04-02-07, 05:15 PM
Grady's Avatar
Forum Topic Moderator
Join Date: Jan 2005
Location: Delaware, The First State
Posts: 13,935
Received 1 Vote on 1 Post
Flares/Filters

Never, ever, use any kind of sealant on the flares. To do so risks damage to the pump should any of the sealant manage to get into the fitting. A drop of motor oil on the face of the fitting is a good idea. I feel double flaring to be overkill & unless you are very good at it, you increase the risk of a leak. Double flares are normally only used on high pressure applications such as brake lines.

I am a firm believer in the theory of no such thing as too much filtration. I have had two filters on my system since day one. It is common practice today to install a primary filter at or near the tank & a secondary, finer, filter as near the burner as possible.
 
  #9  
Old 04-03-07, 09:26 AM
Member
Join Date: Jan 2005
Posts: 207
Received 0 Votes on 0 Posts
Smile

Originally Posted by Grady View Post
I feel double flaring to be overkill & unless you are very good at it, you increase the risk of a leak. Double flares are normally only used on high pressure applications such as brake lines.
Grady next time you remove a copper flared line look and you will see how thin the flare gets squeezed, copper is soft. After doing my first copper double flare, and seeing how good they looked, never will single flare copper again. I did all my 2 tank plumbing and my camp gas lines double flare.
Actually copper double flare is easy compared to steel, which is near impossible to get right.
It was a no brainer for me I have a full set of double flare adapters.
 
  #10  
Old 04-03-07, 04:51 PM
GregH's Avatar
Super Moderator
Join Date: Jan 2001
Location: Manitoba
Posts: 9,987
Received 8 Votes on 8 Posts
A single flare even with the concerns over CFC ("Freon") leakage is still the standard in the refrigeration/ac trade.
Applying sealant to a flared fitting goes against what is accepted as standard practice in the trade.
It is true that a copper flare has a limited life but the most common reason for the copper to thin out is to not oil the back side of the flare to allow the nut to compress the copper without distorting it.

A double flare on steel brake lines is needed not only because of the higher pressures but also because of the fact that steel will not compress like copper.
The double thickness allows for some compression of the flare.
In the refrigeration trade for steel single flares or even a brass to brass flare fitting a copper flare gasket is used.
 
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
Display Modes
 
Ask a Question
Question Title:
Description:
Your question will be posted in: