The expert system described here is used to design small bore piping i
n nuclear power plants. The system addresses a domain within the autom
atic design paradigm. It is installed in a UNISYS mainframe environmen
t. This paper examines the nature of the small bore piping design doma
in as practiced in the United States and its suitability for expert sy
stem application. The architecture, the context structure, the knowled
ge base, the control module and the implementation of the expert syste
m are presented.