Buoyed by a strong performance in its...

Buoyed by a strong performance in its main engineering and construction business, Fluor Corp. said Thursday that third-quarter profit surged 18%.

For the three months ended July 31, the Irvine-based company posted earnings of $48.3 million, or 58 cents a share. That compares to a profit of $40.8 million, or 50 cents a share, for the period a year earlier. Revenue was $1.96 billion, up 6% from $1.84 billion.

The report “was very much on target,” said Herb Hart, a San Francisco analyst who follows the company for S.G. Warburg Group.

The good news therefore caused little stir on Wall Street. In New York Stock Exchange trading, Fluor stock closed at 53.125 a share, up 62.5 cents.

Fluor quarterly results were lifted by a 23% increase in operating profit at its low-sulfur coal subsidiary, A.T. Massey. The overall operating profit at Fluor’s core engineering, construction and diversified services business was up 17% from a year earlier.