Increased demand for natural gas in the Pacific Northwest has led Salt Lake-based Northwest Pipeline Co. to apply for permission to expand its pipeline, the company's president said Wednesday.

The company is seeking permission from the Federal Energy Regulatory Commission to expand its 3,574-mile interstate pipeline into the Northwest at a cost of about $446 million, said President R.W. Keener.The expanded pipeline would follow the company's current right of way, which begins in northwestern New Mexico, extending to the Canadian border, north of Seattle.

"Contracts for the new capacity have been signed by shippers, reflecting the market's need for this expansion," Keener said. The contracts are for delivery services for 15 years, he said.

Price deregulation of natural gas supplies in the late 1980s "has brought many changes and has spurred growth in natural gas demand in our traditional service area, as well as our system," Keener said.

If approved as submitted, the plans call for: 612 miles of new pipeline, ranging from 24 to 30 inches in diameter; the addition of 150, 000 horsepower of new pipeline compression at 11 new, and 10 existing compressor stations, and replacement or requalification of 104 miles of existing line.