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 3" DWV hairline cracks
Author: HB (TN)

New 3" copper DWV pipe was used to install a 2nd floor bathroom in a historic house 45 years ago. The pipe and its fittings are in a very tight spaces. The chase in the downstairs wall is 4”:x 6” and also contains ½” hot and cold copper supply lines.

A bad solder joint at the base of the sanitary tee developed a small leak allowing a small amount of effluent to trickle out whenever water flowed in the pipe. Traces of limestone scale accumulated on outside of pipe. The bad solder joint has been repaired with FlexPaste and leaks no more, but two hair-line cracks were found 6" and 18" below the repaired sanitary tee joint and leaked very small dribble streams. Both have been repaired with FlexTape, and no more leaks have been found so far. The vertical section of the 3” copper pipe is 12.5’ long.

Should this old pipe DWV be replaced?

To do so will require opening more of the downstairs wall with its decorative plaster and custom wooden, paneling , pilaster, chair rail, baseboard/toe mold.

Soldering is now virtually impossible. Perhaps, there is enough space to use no-hub couplings to join the inlet and outlet section of copper pipe, to a new section of copper, PEX, or schedule 40 plastic pipe.

Please advise, HB

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 Re: 3" DWV hairline cracks
Author: george 7941 (Canada)

That is weird, never seen a copper drain pipe with cracks.Corroded through and leaking, yes, but not cracked

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 Re: 3" DWV hairline cracks
Author: packy (MA)

can you see any color coded lettering on the copper tubing?

if it is yellow color then you have the thinnest tubing available and theere is a good chance that it is just worn out,

red color is thicker and should be repairable

blue color is the thickest of the three and is definately repairable.

so if you have yellow lettering you are in trouble.

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 Re: 3" DWV hairline cracks
Author: Don411 (IN)

My money is on the flex tape

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