3.1. Visual examination During on-site investigation, it was found that the tubing system had 5 parallel lines consisting of two steam transfer tubes, one waste water transfer tube and two ozonated water transfer tubes as shown in Fig. l. The perforation problem was only found on both ozonated water transfer tubes. Close observation of the perforated tubing revealed that the alumi- num jacket was defective in that the silicone used for sealing joints in the jacket was degraded(Pig. 2a) resulting in gaps between the adjacent sections(Fig. 2b). After removing the jacket and insulator from the tube, it was found that accumulated stagnant water was trapped in the insulation as shown in Fig. 2c. lt is believed that the defects in the insulation system al lowed the entry of rain water and condensed moisture which accumulated in the insulation at the bottom of the tube. The(Fug d). The trapped liquid was temperature outside the tube monitored using an infrared thermometer was 303.6 K