Who invented clay pipe?

Clay smoking pipes were first used in Britain in the 16th century following the importation of tobacco from the Americas.

When did they stop using terracotta pipes?

Clay pipes were a common choice in ancient times. In the United States, they came to be used very early on and were still very popular until relatively recently. Clay pipes started being phased out in the 1960s and 1970s when plastic sewer pipe options such as ABS and PVC were developed.