Thread Tools Search this Thread Display Modes
Old 05-17-2015, 11:43 AM   #1
1 Rivet Member
1970 31' Sovereign
Springfield , Missouri
Join Date: Jan 2012
Posts: 12
replacing water lines-copper pipes weird size

We have some issues with our water pipes in our 1970 Airstream. We have purchased pex and connections, but are worried that the copper pipes won't be either 3/8 " or 1/2. They seem to be inconsistent and a little bigger than 3/8" yet a little smaller than 1/2. Any ideas?

NevaH is offline   Reply With Quote
Old 05-17-2015, 12:16 PM   #2
Kevin245's Avatar

Vintage Kin Owner
1973 Avion Travelcader 25' , ...
Join Date: Jul 2007
Posts: 8,978
Images: 9
Most likely freeze related swelling of the existing copper


"You wouldn't worry so much about what others think of you if you realized how seldom they do."

Eleanor Roosevelt

Kevin245 is offline   Reply With Quote
Old 05-17-2015, 12:19 PM   #3
Rivet Master
mimiandrews's Avatar
1966 22' Safari
Weatherford , Texas
Join Date: Jun 2008
Posts: 1,146
If the water lines have frozen, the copper will have stretched to an odd size. We found it impossible to match the existing copper with anything. Worked better to tear out the whole system (after carefully making a diagram) and replace it with 1/2" PEX.
mimiandrews is offline   Reply With Quote
Old 05-17-2015, 12:38 PM   #4
Rivet Master
1974 31' Sovereign
1979 23' Safari
Wayland , New York
Join Date: Jan 2012
Posts: 1,177
Images: 3
Pipe sizes are nominal inside diameters, so 3/8 will be just under 1/2 measured on outside, and 1/2 will be just under 5/8 outside diameter. Varies with wall thickness for different types of copper pipe/tubing as well.
HiJoeSilver is offline   Reply With Quote
Old 05-17-2015, 01:02 PM   #5
2 Rivet Member
sb55's Avatar
2004 25' Safari
South Hero , Vermont
Join Date: Nov 2013
Posts: 90
I don't know for sure what is in an older Airstream, but type K flexible copper tubing is measured differently than the standard type L tubing. Perhaps that is what is in your trailer. You can find this tubing and fittings at McMaster-Carr.
sb55 is offline   Reply With Quote
Old 05-17-2015, 03:11 PM   #6
Rivet Master
87MH's Avatar
1978 31' Sovereign
Texas Airstream Harbor , Zavalla, in the Deep East Texas Piney Woods on Lake Sam Rayburn
Join Date: Jan 2003
Posts: 2,435
Images: 292
I second Kevin245 and Mimiandrews reply above.

I had the same issues when I redid the '78 Sovereign in my signature line.

I managed to get a flare fitting over some lines after polishing the OD with
emery cloth.

"Suck it up, spend the bucks, do it right the first time."

WBCCI # 1113
AirForums #1737

Trailer '78 31' Sovereign

Living Large at an Airstream Park on the Largest Lake Totally Contained in Texas
Texas Airstream Harbor, Inc.
87MH is offline   Reply With Quote
Old 05-17-2015, 04:33 PM   #7
Rivet Master
TG Twinkie's Avatar
1974 Argosy 26
Morrill , Nebraska
Join Date: Nov 2009
Posts: 4,675
Images: 2
Blog Entries: 5
I agree with sb55 TUBING

Sent from my iPod touch using Airstream Forums
Knowledge: "A gift to be shared. A treasure to receive."
TG Twinkie is offline   Reply With Quote
Old 05-18-2015, 10:41 AM   #8
4 Rivet Member
1977 31' Sovereign
Lynnwood , Washington
Join Date: Jan 2015
Posts: 280
There are two scenarios:

1) Some time during your AS's lifetime, the water lines froze and as a consequence, they have expanded.

2) There's copper "pipe" and there's copper "tubing." The sizes are slightly different.

a) In my 77 AS, I've got copper tubing. It took me a while before I figured this out. Get a micrometer and measure OD carefully. When doing a repair, outside diameter is what counts.

FYI - I use "L" tubing for repair and upgrades. It bends easily and without kinking. You'll need a tubing bender. Harbor Freight has cheap ones that work just fine.

b) My lines have also expanded (in places) and split (in 2 places) due to freezing. As a consequence of that, I've learned to choose my repair/upgrade jobs very carefully. There are times when you hafta "make do" with what you've got and leave "well-enough" alone.

TomKirk is offline   Reply With Quote
Old 05-18-2015, 03:41 PM   #9
4 Rivet Member
1967 26' Overlander
Spartanburg , South Carolina
Join Date: Jan 2011
Posts: 270
As I recall, there are two types of copper tubing, hard and soft. I have no hands on experience with the hard type which is usually joined by soldering into similar alloy fittings. The soft type I believe can also be soldered but is often joined by brass compression or flared fittings. It is somewhat maleable and over time, even if not over pressured, can actually "creep" and expand slightly which makes it too tight for compression type fittings. It can sometimes be sanded on the outside slightly to accomodate a flared fitting and if so, may well work ok. Flaring, of course, requires a special tool and care must be taken to cut the end perfectly square.
Jacob D is offline   Reply With Quote
Old 05-18-2015, 03:58 PM   #10
Wise Elder
Jammer's Avatar
2010 30' Classic
Vintage Kin Owner
South of the river , Minnesota
Join Date: Dec 2009
Posts: 4,020
Freeze related expansion as others have noted.

Tricks to try if you are trying to connect to expanded copper.

1) Try to find a join point that isn't as badly expanded. Some areas will be worse than others. Curved areas will usually be worse because the tubing deforms in shape somewhat when it is bent.
2) You may be able to squeeze the pipe back down to size with the clamp part of the flare tool, enough to get a flare nut on. Polishing the pipe with emery cloth may help if it is dirty and corroded, but don't remove too much material or the result will leak.
3) You may find you can place a piece of new 1/2" copper over the existing expanded 3/8" copper, overlapping about 1" or so, and solder the two pipes together. Then you can connect the 1/2" copper using the method of your choice.

To learn to see below the surface, you must adjust your altitude
Jammer is offline   Reply With Quote

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

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

Similar Threads
Thread Thread Starter Forum Replies Last Post
Advice on replacing copper water lines bdiem Fresh Water Systems 6 06-03-2013 12:56 PM
Replacing Copper Pipes jbrownokc Plumbing - Systems & Fixtures 26 09-22-2010 08:40 PM
replacing copper water lines purman Fresh Water Systems 6 07-26-2008 10:25 AM
replace old copper water lines with plastic pipes m. Clarke All Argosy Trailers 7 03-26-2004 11:42 PM

Virginia Campgrounds

Reviews provided by

Our Communities

Our communities encompass many different hobbies and interests, but each one is built on friendly, intelligent membership.

» More about our Communities

Automotive Communities

Our Automotive communities encompass many different makes and models. From U.S. domestics to European Saloons.

» More about our Automotive Communities

Marine Communities

Our Marine websites focus on Cruising and Sailing Vessels, including forums and the largest cruising Wiki project on the web today.

» More about our Marine Communities

Copyright 2002-2015 Social Knowledge, LLC All Rights Reserved.

All times are GMT -6. The time now is 11:54 PM.

Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2016, Jelsoft Enterprises Ltd.

Airstream is a registered trademark of Airstream Inc. All rights reserved. Airstream trademark used under license to Social Knowledge LLC.