Thermal Imaging for Inspection of Large Cryogenic Tanks

The end of the Shuttle Program provides an opportunity to evaluate and possibly refurbish launch support infrastructure at the Kennedy Space Center in support of future launch vehicles. One major infrastructure element needing attention is the cryogenic fuel and oxidizer system and specifically the cryogenic fuel ground storage tanks located at Launch Complex 39. These tanks were constructed in 1965 and served both the Apollo and Shuttle Programs and will be used to support future launch programs. However, they have received only external inspection and minimal refurbishment over the years as there were no operational issues that warranted the significant time and schedule disruption required to drain and refurbish the tanks while the launch programs were ongoing. Now, during the break between programs, the health of the tanks is being evaluated and refurbishment is being performed as necessary to maintain their fitness for future launch programs. Thermography was used as one part of the inspection and analysis of the tanks. This paper will describe the conclusions derived from the thermal images to evaluate anomalous regions in the tanks, confirm structural integrity of components within the annular region, and evaluate the effectiveness of thermal imaging to detect large insulation voids in tanks prior to filling with cryogenic fluid. The use of thermal imaging as a tool to inspect unfilled tanks will be important if the construction of additional storage tanks is required to fuel new launch vehicles.