An expert system is developed to aid in the selection of bakeout time and temperature during the manufacturing process of a heatpipe. Simplicity of this system allows it to be written in a low level programming language, instead of using a high level expert system shell. The expert system involves an interactive process using a forward chaining inference. The surface outgassing rate and the residual gas requirement are inherently uncertain. The uncertainty associated with the outgassing rate is represented graphically, and an appropriate uncertainty factor is used. The threshold of permitted residual gas is determined by the knowledge-based system. The expert system shows pass or failure at each inference. A summary graphic is generated showing the domain of success.