Williams Cos. says it will create one of the largest natural gas partnerships in the nation by combining pipeline and processing units.

The new company will have a presence from the Rocky Mountains and the Gulf Coast to the Northeast.

Williams, based in Tulsa, Okla., will get about $3.5 billion in cash from Williams Partners to help pay down debt and will contribute its substantial assets to the new, larger Williams Partners.

The parent company gets about 203 million in shares and its ownership share increases from 24 percent to 80 percent.

One key asset that Williams will contribute to the partnership is the Texas Transcontinental Gas pipeline, which runs to the bountiful Marcellus Shale of Pennsylvania.

The company values the deal at about $10 billion, plus $2 billion in debt.