NOTE: Restrictions are in place to limit access to one or more of the files associated with this item. Authorized users must log in to gain access. Non-authorized users do not have access to these files.
Visit the Energy Systems Laboratory Homepage.
Location of Leaks in Pressure Testable Direct Burial Steam Distribution Conduits
MetadataShow full item record
Central steam is commonly distributed through direct burial lines protected by an outer conduit. These underground conduit systems are subject to electrolytic corrosion. Failure of the outer casing permits water intrusion and damage to insulation, resulting in increased thermal energy losses and eventual damage to the steam line. Breaches in the outer conduit are difficult to locate, and damage to the steam line may progress until the entire line requires replacement. Thermal energy losses are high if groundwater infiltrates the conduit and excavation to replace the steam line is extremely expensive. Locating leaks in steam line conduit is a two step procedure. The first step is to regularly pressure test sections of conduit to determine whether a breach has occurred. Pressure testing should be performed on a regular basis to minimize thermal losses and damage from groundwater intrusion. If pressure testing reveals that the conduit is leaking, the Navy has developed a procedure and equipment to determine where the breach occurred. The breach can be detected using sulfur hexafluoride (SF6) tracer gas injected into the conduit. After injection, maintenance personnel walk the path of the steam line with an SF6 detector that precisely locates the leak. Then, only the necessary conduit sections are excavated for repair. We have successfully used this system at several locations, and in a variety of soil conditions. Tracer gas leak testing provides an effective and inexpensive method to evaluate underground conduit systems. Performed on a regular basis, it is a useful preventive maintenance tool to minimize energy loss and utility system damage. Test results also provide valuable input to the decision to repair or replace underground steam lines. This equipment and procedure may be used on other utility system distribution components, such as compressed air and direct burial steam lines.
Sittel, M. G.; Messock, R. K. (1993). Location of Leaks in Pressure Testable Direct Burial Steam Distribution Conduits. Energy Systems Laboratory (http://esl.eslwin.tamu.edu). Available electronically from