Annual Cathodic Protection Survey, Leak Survey and Ground Patrol of a 13-Mile Natural Gas Line, Eastland Area (2025)

Once a year a gathering operator near Eastland has the cathodic protection on a 13-mile natural gas line checked, and in June 2025 we added a ground patrol and leak survey to the same trip.

One rectifier for 13 miles

A single rectifier at the compressor station on the north end protects the line, with nine test points along the alignment: the rectifier, four test stations, three valve settings and the delivery station on the south end. No design drawings or calculations were available. The rectifier was running normally at 5.4 V and 5.9 A. Its junction box carried ten anode leads through shunts, which points to a deep groundbed. Nine of the ten anodes were delivering current, from 0.16 to 1.77 A; one read zero.

The interrupted survey

With an interrupter cycling the rectifier 4 seconds on and 1 second off, we read every test point we could reach. One test station near a railroad crossing could not be found. The other eight ranged from -1,070 to -1,300 mV instant-off, all meeting the criteria of NACE SP0169-2024. The line is isolated at the delivery station, and the flange kit there was working. To the north it is continuous with other piping of the same operator, but other rectifiers had little effect on the readings.

The patrol

Over the same three days the crew drove the right-of-way by UTV, located the centerline with a pipe locator and sampled the air at the ground surface with a calibrated gas detector, bump tested each day. We also looked closely at the five aboveground sites: the launcher and receiver bays at each end and three valve settings. There were no leaks and no damage to aboveground piping, only minor overcoat and coating damage at three sites. One crossing at a creek had exposed pipe, likely from washout. Much of the right-of-way was unmowed, some of it too overgrown to cross, and several gates had been replaced with fencing or had the locks removed, which limited access.

Related services

Annual checks like this one are part of our interrupted potential surveys. For gas systems, see gas piping cathodic protection.