NEW YORK, JULY 16 -- A U.S. bankruptcy court judge today approved an interim agreement between LTV Corp.'s steel subsidiary and the United Steel Workers of America that reportedly will save the troubled company $50 million.

Judge Burton Lifland issued his bench ruling after a five-hour hearing in Manhattan, during which the federal Pension Benefit Guaranty Corp. objected to the pact covering 18,000 active and 8,200 retired workers of the Dallas-based company's steel-producing unit.

The PBGC, with total assets of $3 billion, faces $7 billion in obligations under plans for which it is now trustee.

The pension agency argued that the agreement, to be voted on by union membership next month, would serve as a reorganization plan for the company, restoring $400 monthly supplements to its retirees and forcing the PBGC into insolvency.

Such an occurrence, it said, would threaten the pensions of 40 million American workers.

The federal agency, which took over Cleveland-based LTV Steel Co.'s pensions after the parent company filed for bankruptcy court protection last summer, has contended that businesses such as LTV have an incentive under the current law to dump their pension plans onto the government and then reach agreements to pay their retirees supplements that are not covered by the federal unit.

Union sources said the pension agreement would save LTV $50 million.

The accord maintains the current wage agreement that was reached in April 1986 but adds a $26.82 monthly charge to workers and retirees for health care benefits. It also calls for the elimination of 516 jobs through attrition.

"This will help to resolve some of the most troubling issues" before the steelmaker, said Lifland, "help to ensure labor peace alleviate extreme hardship to retirees."

As for PBGC's woes, Lifland suggested that the agency seek legislative relief or deal with pension problems on an "ad hoc case by case" basis.

PBGC's attorney, George Weiss, said, "We shall appeal."

The appeal would be in U.S. District Court after Lifland's bench ruling is delivered in written form.