Dresser Industries Inc. reported earnings of $44.5 million or 62 cents a share for its first 1988 fiscal quarter ended Jan. 31, compared with a loss of $7.8 million or 10 cents a share for the same period of fiscal 1987.

Dresser attributed the turnaround to improved domestic drilling activity, a weak U.S. dollar and benefits from joint ventures and acquisitions.First-quarter earnings include $34 million from the sale last November of Reliance Standard Life Insurance Co.

Revenues in the first quarter of $801 million were up 12 percent from $717 million in the same period a year ago. The increase in revenues was due partly to the acquisition last year of M.W. Kellogg Co., a leading energy engineering and construction firm.

The Dallas-based company also announced that it has signed a letter of intent to sell its Bay State Abrasives Division in Westborough, Mass., and its General Abrasive Division of Niagara Falls, N.Y., to Sterling Abrasive Products Co. based in Clearwater, Fla.

Terms of the pending sale were not disclosed. The combined revenues of the two abrasives operations exceeded $100 million in the past year.

Earlier this month, Dresser announced a joint venture with Komatsu Ltd. of Japan. The two previous competitors will combine their construction equipment business, increase manufacturing capacity in the United States and reduce imports from Japan.

An analysis of the Dresser-Komatsu joint venture recently published by Salomon Brothers Inc. estimated combined sales to be in excess of $1.1 billion. Komatsu has one manufacturing plant in Tennessee and exports an estimated $300 million to $350 million of construction equipment into the North and South American markets annually. Dresser has two large manufacturing plants in Illinois and one in Ohio that run at an estimated 50 percent of capacity.

Manufacturing a sizable percentage of Komatsu's volume in Dresser's plants will increase capacity utilization and allow the plants to operate more profitably, the Salomon Brothers report said.

The combination of Dresser and Komatsu gives them about a 20 percent market share and allows them to be more competitive on a cost basis with Caterpillar Inc. - the dominant construction equipment company with about 45 percent of market share.

The abrasives operations divestiture and the Komatsu joint venture are the latest moves in a restructuring of Dresser that began in 1983. Since then the company has entered into seven joint ventures, sold 16 units or divisions and made six acquisitions.

The company also announced that its board increased its quarterly common stock dividend to 12.5 cents a share from 10 cents a share.

The board's dividend decision reflects substantially improved operating performance and the increased overall competitiveness realized as a result of the company's comprehensive restructuring programs, said John J. Murphy, Dresser's chairman and president.

Dresser is well-positioned for the future, Mr. Murphy said.

Mr. Murphy attributed the improved operating performance in the 1988 first quarter to a 22 percent increase in average domestic drilling activity

from a year earlier, reduced pricing discounts for certain oil field equipment and services, economies of scale derived from joint ventures and the lower value of the U.S. dollar having favorable impact on exports.