internal pressure near 7.4:1. In addition to the tank itself, the development effort includes a riser design. The proposed riser extends to the ground surface from one of the composite propane tank end openings. This riser includes a vertical pipe housing a tube to connect the vapor space of the vessel and riser, and space for a fluid level sensing system. The riser pipe is topped with a combination valve typically used for underground service applications. A gusset system is included for stabilizing the riser to the vessel during transport. Figures ES-1 and ES-2 show engineering renderings of the current composite propane tank design.
In order to help strengthen the case in support of composite use as an alternative to steel for underground propane tanks, a materials compatibility evaluation was performed using literature data to assess the compatibility of the proposed composite materials with components found in commercial propane. There were no laboratory tests performed on this project. We believe that there are no issues of concern at this point regarding chemical compatibility. The details of the materials compatibility study are detailed in a subsequent section of this report.
It is of importance to note that the appurtenances in the alternative materials composite propane tank are metallic and, therefore, subject to potential corrosive deterioration. The appurtenance corrosion issue is also addressed in a subsequent section of this report, and it is believed to be manageable in most underground environments.
Figure ES-1. Side View Rendering of Preferred Underground Composite Propane Tank
Alternative Underground Propane Tank Materials, Phase II—Final Report
September 2009 Battelle and Lincoln Composites