It’s a basic fact of science: when steel pipelines are buried underground, corrosion inevitably occurs.

So how do we ensure the integrity, safety, and reliability of our underground natural gas pipelines, which are made of steel?

To fight corrosion, we employ a technique called cathodic protection, which literally uses electrical currents to prevent rust.

With cathodic protection, a flow of electrical current is applied from an external source – a rectifier – through the ground and onto the steel pipe. The protective current changes the environment around the steel, stopping the corrosion reaction.

Here’s an interesting fact: if steel pipes have cathodic protection and maintained within safety standards, they can last forever. How’s that for safety?

6,500 miles

The SDG&E System Protection Team, comprising 18 technicians, works year-round to repair and maintain the gas distribution system to prevent leaks. Their critical work involves driving more than 200,000 miles per year for inspections and construction on more than 6,500 miles of steel gas pipelines, which are spread throughout San Diego County.

A typical day

A typical day for the team consists of monitoring the cathodic protection system, taking reads on the equipment which monitors the current, troubleshooting and ensuring everything is within the levels they should be. When walking around your neighborhood, you may notice metal boxes mounted to utility poles. Those are cathodic protection rectifiers. The rectifiers put a small amount of direct current onto our steel pipes underground to protect the pipes from corrosion. We monitor and survey these rectifiers on a regular basis to ensure the integrity of our pipelines.

All of SDG&E Cathodic Electricians are certified by the National Association of Corrosion Engineers.

As a 17-year veteran of SDG&E, Cathodic Protection Electrician Michael Nelson finds the day-to-day work rewarding.

“My favorite part of the job is interacting with customers. It’s the best part of my day. When you work by yourself and someone wants to come up and talk to you and ask questions, I find that very rewarding to explain to customers how what I’m doing helps to keep them safe.”