Oil pipeline magnate raised in poverty in rural Texas; lost mother, brother at age 7. Moved in with grandmother. Cofounded Enterprise Products 1968; met customers' delivery needs with 2 trucks. Today firm presides over 35,000 miles of oil and gas pipelines, opened a $630 million deepwater natural gas platform and pipeline in the Gulf of Mexico last year. Planning to build $2 billion oil port off Texas coast. In June held Republican fundraiser at his Houston home; guest list included Dick Cheney. Seasoned hunter decorates walls of Texas ranch with heads of animals he's killed. Donated $270 million to medical research and education in the past 5 years. Mr. Duncan is survived by his wife, Jan; a son, Scott; three daughters, Randa Duncan Williams, Dannine Duncan Avara and Milane Duncan Frantz, all of Houston; and four grandchildren.