This paper describes the analysis method we used in the E.C. ESPRIT technology transfer project VIPLAST_2 for the detection of defects in industrial plastic components for automatic drop irrigation. The analysis process verifies that the design rules of prism-shaped drippers are met before they are soldered at a regular distance within a drop pipe and afterwards it points out missing or misplaced holes drilled on the pipe surface overlapping the dripper. Our method faces problems arising from the visual features of the object material, such as highly reflective surface and absence of texture, and handles variable lighting conditions and unstable object positioning namely overturning, jitter and rotation. Experimental results on the industrial production lines are given. They show the reliability of our method, obtaining a very high rate of detected defects and a low rate of false alarms. The company real time inspection requirements are also met.