Joseph Keen Rulon, 95, a Washington restaurateur who with his twin brother owned and operated Hogate's seafood restaurant on the Southwest Washington waterfront for more than 25 years, died Aug. 30 at Massachusetts General Hospital in Boston of complications after heart surgery.

Mr. Rulon, a mechanical engineer with the DuPont Co. in Wilmington, Del., moved to Washington in 1946 to join his brother, Watson B. Rulon Jr., in the operation of Hogate's, a dining institution in the nation's capital in a century-old building at Ninth Street and Maine Avenue SW. Before it became Hogate's restaurant in 1935, the building was a steel foundry and later the Washington Aeroplane Co., which was said to have been the nation's first commercial airplane factor.

Until 1972, when the restaurant moved across the street to a new and larger facility with a seating capacity of 900, Hogate's was managed by the Rulon brothers, who in their capacity as leading businessmen in the neighborhood were among the major players in the urban renewal of Southwest Washington. With the relocation of Hogate's to the new $3 million facility, the Rulons turned management of the restaurant over to the Marriott Corp. and retired.

In 1976, Joseph Rulon moved to Scituate, Mass., where he resided until his death. His brother died 10 years ago.

Mr. Rulon, a native of Philadelphia, attended the University of Pennsylvania and graduated from Swarthmore College. After college, he worked 20 years for DuPont, where he rose to become chief of the X-ray film division. During his years with DuPont, he was awarded nine patents, including the bite wing X-ray film strip, which is used by dentists all over the world to X-ray teeth. During World War II, he worked with the DuPont film division on the Manhattan Project, which developed the atomic bomb.

Moving to Washington after the war, Joseph Rulon joined his brother in the management of a restaurant that since 1935 had been one of the city's major seafood dining places. The original owner was John Hogate Whitakar, a New Jersey physician who had been the Rulons' family doctor. After running the business for three years, he decided to retire and he asked Watson Rulon to move to Washington and take over the restaurant, which he did.

With a seating capacity of 600, the old Hogate's claimed to be the second largest restaurant in a single building in the United States. Typically, 1,000 guests, as the Hogate's management insisted on calling its customers, showed up for weekday lunches of crab imperial, deviled clams, deep sea scallops, broiled swordfish, french fries and coleslaw, accompanied by Hogate's own rum buns.

In the late 1950s and early '60s, urban renewal came to Southwest Washington and much of the area was torn down and rebuilt. The Redevelopment Land Agency wanted to demolish the building in which the old Hogate's was located. After extensive negotiations, RLA agreed to the construction of a new Hogate's across the street, and two days before Christmas of 1971, the old Hogate's closed.

"We feel that a very important Washington institution is fading out. It has a quality which will be very hard to duplicate, a kind of homey, personal attention that is unique in the metropolitan area," one of the luncheon regulars told The Washington Post when the old Hogate's closed. The new facility opened in the spring of 1972.

Joseph Rulon was a board member of the Hospital for Sick Children in Washington and Travelers Aid. He was vice president of the National Fisheries Institute and president of the New England Seafood Co.

He was a member of the Chevy Chase Club.

His wife, Anna Neilson Rulon, died in 1989.

Survivors include a daughter, Martha Rulon Frazier of Washington; three grandchildren; and two great-grandchildren.