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Investigation of PVC Pipe Failure at Terrell State Hospital – Final Report
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At the request of Terrell State Hospital and MHMR, the Energy Systems Laboratory at Texas A&M University investigated the failure of the PVC pipes serving the chilled water loop at Terrell State Hospital. There were two PVC pipe failures where the PVC pipe bulged out. Based on laboratory test result and trend data from the building automatic control system, it is concluded that the deadheading of building chilled water pump caused the failure. However, it is not clear what caused the building isolation valve to close that resulted in pump deadheading. We are still investigating the cause.
DescriptionThe failed PVC pipe was sent to Materials Performance Inc for testing. Short and long-term mechanical properties were compared for a section from the failed pipe and a new PVC pipe. Results on both tests indicate that the mechanical properties for the failed pipe were similar to that of a new PVC pipe. The possibility of defective PVC pipe material that caused the failure was ruled out. Several pressure transmitters were installed in various locations throughout the chilled water loop. Monitoring of the chilled water loop pressure did not show unusual water pressure in the loop. During the course of this investigation, it was found from the building automation system that the failed section of the PVC pipe was located closed to a chilled water pump which had been accidentally deadheading for over 52 hours prior to the second failure. It is concluded that the failure of the PVC pipe was caused by high temperature inside the pipe as a result of pump deadheading. This conclusion is strengthened by high chilled water temperature measured (170°F) after similar chilled water pump deadheading situations occurred in buildings at Texas A&M recently.
- Technical Reports 
Wei, G.; Deng, S.; Claridge, D. E.; Turner, W. D. (2000). Investigation of PVC Pipe Failure at Terrell State Hospital – Final Report. Energy Systems Laboratory (http://esl.tamu.edu), Texas A&M University. Available electronically from