A Maryland steelworkers union has sued to remove a member of the Maryland Occupational Disease Board, charging a conflict of interest "so immense" that workers at Bethlehem Steel, the state's largest industrial employer, cannot get a fair hearing on disease claims.

The 8,000 members of Steelworkers Local 2610, the larger of the two unions at the steelmaker's Sparrows Point plant, asked U.S. District Court in Baltimore Friday to stop Dr. J. Howard Franz, a Bel Airradiologist, from participating in cases before the board, which decides whether workers suffering from chronic illnesses are entitled to workmen's compensation payments.

The union claims that Franz's presence "casts a cloud over theentire Workmen's Compensation Commission" because of his private employment with Bethlehem Steel. Franz has held a position on the board since 1972.

Franz, 64, told The Washington Post last month that he had been a paid consultant for Bethlehem Steel and other Maryland industrial firms for the past 20 years, and said: "I have never felt there was any conflict of interest." He could not be reached for comment on the lawsuit.

In his complaint, union president Joe Kotelchuck charged that the steelworkers are denied access to an "impartial" and "untainted" X-ray expert on the board because of Franz' outside employment.