Piedmont Natural Gas filed a request with the North Carolina Utilities Commission to raise its base rate by 9 percent, its first increase in six years.

If approved by regulators, Piedmont anticipates the new rates to go into effect by the end of 2019.

If the rate hike is approved, Piedmont’s average residential customer could expect a monthly bill increase of about $6. The increase would raise about $83 million annually in new revenue for the company.

“Customer growth and our commitment to operating a natural gas pipeline system that meets the highest safety and reliability standards required critical investment over the past six years,” said Frank Yoho, executive vice president and president of Piedmont, in a statement. “Upholding these standards is the very foundation of our commitment to our customers and the communities we serve.”

Some of this investment is required by the U.S. Department of Transportation and the Pipeline and Hazardous Materials Safety Administration as part of broad pipeline regulations.

If the increase is approved, rates would remain below the price customers were paying in 2008, largely as a result of continued lower natural gas prices.

Since the last rate increase, the company’s customer base grew to 750,000 from 700,000, a 7 percent increase. Residential customers constituted the bulk of that increase.

Piedmont’s general rate increase is the first sought by the company since 2013.

The company got a 3.6 percent rate hike in 2013, following an agreement with the Public Staff of the N.C. Utilities Commission to reduce the increase from the initially proposed 9.5 percent.

Its last hike before 2013 was in 2008, when it got a 1.5 percent increase.

Piedmont Natural Gas is a subsidiary of Duke Energy Corp.