The 1-1/2" copper waste pipe than runs from our kitchen just up and cracked two days ago along its length, and for no apparent reason.

[![enter image description here](https://i.stack.imgur.com/Okw2y.jpg)](https://i.stack.imgur.com/Okw2y.jpg)

The crack is in a section of pipe that runs vertically through the kitchen floor down into the basement, where it connects to an angled length of pipe (two 45-degree elbows) and then a section of pipe that connects to cast iron sewer pipe (lead and oakum seal). 

[![diagram](https://i.stack.imgur.com/ygX9n.png)](https://i.stack.imgur.com/ygX9n.png)

I would venture to say that this cracked pipe is from the 1970s (when former owners remodeled the kitchen) and that the section of copper pipe (which didn't crack) going into the cast iron hub dates from around 1948-49, when the house was built.

Could the crack have been the result of twisting forces when the pipe connection was made to the garbage disposal beneath the sink? Or does copper waste pipe just eventually give out, perhaps because of corrosion over a period of 50 years?