My friend (and one of the folks that got me singing in the rain in the first place), Lori Cofer, has a post up on Orangeburg Pipe (member's only). She has most of the basics right (good job, Lori!) and I thought I would fill in some history.
Orangeburg Pipe (or bituminious fiber pipe for the code nerds out there) made it's first appearance in the 1860's in Boston where it was used for an experimental water delivery pipe. By all accounts, the experiment was a success and the water service was used until 1927.
The pipe is constructed from a combination of cellulose and asbestos fibers (what a wonderful and versitile material asbestos was!) saturated with a bituminious compound. In place of bituminious, think coal-tar. The joints were made of similar material and did not have any joint sealant.
That lack of sealant makes Orangeburg very susceptible to tree roots. It also doesn't handle pressure well. Sewer lines are gravity lines and here the material found a home in residential construction.
Demand for Orangeburg Pipe grew rapidly in late 1940's through the 1960's. It was cheaper than metal pipes and easier to cut and handle than clay.
The anticipated lifespan is about 50 years. We're at the end of the cycle for this product. It was phased out in the late 60 and early 70's in favor PVC piping.
Since Orangeburg Pipe was used primarily underground, it's particularly difficult to identify. Home inspectors don't dig up sewer lines for verification. All we can work with is educated suspicions and suggest follow up efforts by the plumbers.