Pan American World Airways Inc., yesterday reported a net profit of $94.6 million for 1976 compared with a net loss of $46.1 million in 1975. The profit, equal to $2.24 a share, came on revenues of $1,662 billion, versus 1975's loss of 20 cents a share on revenues of $1.606 billion.

The earnings turnaround was similar to that reported earlier by other major U.S. airlines. Chairman William T. Seawell said the company has "come a long way," since early in 1975 when it was "running at a net annual loss rate of almost $120 million."

Tenneco, Inc., yesterday reported record 1976 earnings of $383.5 million ($4.15) in 1975. Operating revenues were $6.4 billion compared with $5.6 billion in 1975.

Fourth-quarter earnings were 91.7 million ($1.01) compared with $80.4 million (93 cents). Operating revenues increased from $1.4 billion to $1.7 billion.

Wilton E. Scott, chairman and president, said all of Tenneco's major business had increased revenues and income.

Johns-Manville Corp., a diversified manufacturer of building insulation products, reported that net profit rose the equivalent of 60 cents a share in 1976.

Net income was $53.4 million ($2.64 compared with $38.4 million ($2.04) in 1975. Sales rose from $1.107 billion to a record $1.309 billion.

The company also mines and markets asbestomite and perlite.