Bumps on Copper Drain Waste Pipe

[DIYJeff2016]

Hey everyone! Was wiping down some pipes downstairs as we were doing some general cleaning, and discovered that one of the larger copper waste drain pipes has all these bumps on it. This pipe is about 4-5 feet long, and these bumps exist almost the entire length.

It also appears that i knocked a bump off, and there is a hole underneath which is now leaking a little.

We've never had any leaks prior. What are these? What causes it?

Thanks!

 

[Twowaxhack]

The pipe is being attacked. Probably by sewer gas from the inside out. High concentrations of sewer gas will make Swiss cheese out of copper

That’s what it looks like.

 

[BlueSkyHigh]

Holey moley! I had no idea!

 

[CT18]

Or someone dumped some type of chemicals down the drain