National Steel Corp., the nation's fourth-largest steel producer, yesterday announced a net loss of $96 million for the third quarter of 1982, while Delta Air Lines reported a $16 million loss for the first quarter of fiscal 1983, the second loss in the airline's history.

Meanwhile, American Brands Inc., said its third-quarter profit rose 6.7 percent from a year earlier.

National Steel said revenues for the third-quarter of 1982 totaled $803 million, off 25 percent from the nearly $1.08 billion in the comparable quarter a year ago, when the company reported a profit of $34.6 million ($1.85 a share).

National said the third-quarter loss included a $55.4 million write-off of permanently idled facilities, among them an iron ore property in Minnesota and equipment at two coal facilities in Pennsylvania and West Virginia.

For the first nine months of 1982, National posted a net loss of $186.1 million, including $73.6 million in write-offs. That compared with earnings of $69.3 million ($3.70) during the comparable 1981 period. Revenues for the first nine months of the year totaled $2.44 billion, off 25 percent from revenues of $3.24 billion during the same period last year.

National Chairman Howard Love blamed the sluggish domestic economy, compounded by a worldwide recession, for the company's poor financial showing and said more of the same likely can be expected.

In Atlanta, Delta Air Lines reported a $16 million loss yesterday for the first quarter of fiscal 1983 -- the second loss in the history of the airline.

The unaudited loss of $16.1 million (41 cents) in the quarter ending Sept. 30 compares with net income of $7.6 million (19 cents) during the same quarter last year.

"The loss in the current quarter is directly related to a 5 percent decline in passenger traffic, the result of the depressed economy and Delta's attempt to improve its passenger-mile yield by offering a reduced number of discount seats," said Robert Oppenlander, Delta senior vice president of finance.

Oppenlander said Delta increased its passenger mile yield by 4 percent to 14.11 cents, "but the yield increase was not enough to offset the decline in traffic."

"Total operating revenues declined 2 percent to $876.5 million while passenger revenues were $812.2 million, down 2 percent. Cargo revenues increased 1 percent," Oppenlander said.

Operating expenses were $915.7 million, an increase of less than 3 percent. Delta suffered an operating loss of $39.2 million.

Delta reported its first loss earlier this year.

American Brands cited growing market shares of some of its consumer products lines for its increase in third-quarter profit. The company is a leading maker of cigarettes, distilled whiskeys and golf equipment. It also has interests in office products and snack foods.

Chairman and Chief Executive Edward W. Whittemore said that despite the recession, the company's American Tobacco Co. unit "had a record quarter, and several of our industry-leading lines, such as Jim Beam Bourbon, have strengthened their position by securing a growing market share."

In the latest quarter, profit rose to $93 million ($1.59) from $88 million ($1.51) a year earlier. Third-quarter sales edged up to $1.68 billion from $1.66 billion.

For the first nine months of this year, American Brands' net income fell to $277 million ($4.75) from $283 million ($4.90), in the comparable 1981 period. Sales gained slightly to $4.89 billion from $4.88 billion.

American Brands noted that in the year-earlier nine-month period, earnings included $57 million in one-time, tax-related adjustments and credits.

Hershey Foods Corp. earned $1.77 a share in the third quarter, up from $1.68 a year ago, as sales rose to $443.02 million from $386.78 million. Net income climbed to $27.82 million from $23.9 million. Nine-months profit was $70.54 million ($4.50) on sales of $1.148 billion against $59.4 million ($4.19) on sales of $1.066 billion. The 1982 per share profit was on 1.5 million more shares than were outstanding in 1981.

Vice Chairman E.C. Dearden said the Hershey Chocolate and Friendly Ice Cream and restaurant divisions both had strong sales gains.