Pan American World Airways will begin flying next month to Tulsa, Oklahoma City and New York's Kennedy International from Dulles International.

The company also will add nonstop flights from National Airport to Tampa-St. Petersburg and to Ft. Myers, Fla. The new flights start June 1, company representatives said.

PLANT SHUTDOWN: Reynolds Metals Co. said yesterday that it will shut down temporarily two aluminum potlines at its Longview, Wash., plant. Each of the potlines has an annual capacity of 23,000 tons. Reynolds said the shutdown is caused by weak demand and the Washington plant was chosen for the shutdown because it has high energy costs.

OVERTIME AT FORD: Ford Motor Co., which still has nearly 700 workers on layoff in Norfolk, announced yesterday that employes remaining on the job will get overtime work.

The assembly plant, in Norfolk's Campostella area, has operated one shift of nine hours a day, or 45 hours a week, this week.

Ford said the overtime schedule will continue at least one more week and that truck sales, which rose 18 percent last month, will determine the extent of the overtime.

There are, however, no plans to reinstate the plant's second eight-hour shift, which was canceled on Feb. 1, laying off 710 assembly line and supervisory workers. Since then Ford has recalled 81 assembly line workers.

Ford said truck sales continued to rise in April, although passenger car sales remained depressed. The company's dealers sold 72,068 trucks last month, up 18.4 percent from 60,846 vehicles in April 1981. Passenger car sales declined 11.7 percent to 113,815 vehicles last month.