SALT LAKE CITY — Questar Gas announced Monday that it is asking the Utah Public Service Commission for a $19 million increase in its Utah general rates.

If approved, the increase would add about $1.36 to the average monthly bill for residential customers — or less than 2.5 percent — beginning March 1, 2014.

This general-rate request covers the costs of system maintenance and expansion, Questar officials said, and does not include the cost of natural gas that the company buys for its customers. Gas costs are passed on to customers without markup, company officials said.

“This request is necessary to ensure our system’s reliability and safety,” said Craig Wagstaff, Questar Gas executive vice president and chief operating officer. “We’re asking state regulators to allow us to maintain the high levels of service and reliability our customers have come to expect.”

Questar estimates it will need to invest about $200 million annually over the next few years to ensure safe, reliable service to existing customers and to meet growing demand for natural gas.