Checking for Leaks

What is the recommended method for testing 3/8 copper oil feed lines for an oil furnace for leaks? Pressure or vacuum? Is there a life expectancy for copper that is buried in the ground or possibly in concrete? These lines run under the concrete basement floor, so before I replace them I want to test them. They are about 50 years old and have been working as far as I know.
Thanks
R
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Burying fuel pipes come under the heading of very bad ideas.
You can test it using the fuel.
Providing the valves are tight and there is positive pressure on the line just attach a pressure gauge and close the fuel line valves, I assume there is one at each end. You first need to drop the pressure in the line and watch the pressure does not rise. This checks that the valves are not passing. Then let the pressure up by opening a valve and then closing it. Check then that the pressure does not fall indicating a leak.
The objectof the above is to ensure that faulty valve (passing) does not more than offset a leak. ie fuel is leaking in quicker than it's leaking out somewhere.
But he only way to be sure is visual inspection. Maybe best to abandon the line & put in new (but not buried)
Concrete being alkaline is metal friendly. (Earth might not be). The problem tends to arise where the pipe goes into the concrete when strange things happen.
If you must bury it, install it in a plastic duct so the pipe can be pulled out for renewal. Plastic covered copper is available over here (UK) too for hostile environments. I expect you have it over there too.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

These days you run it above ground. Over many years, some copper lines have pin-holed. This is true of oil lines and baseboard heating lines. I'd use pressure to test it, but there may be other methods.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.