BATH — Bath Iron Works will lay off 42 employees effective Oct. 11, the company confirmed Friday. The layoffs affect insulators and pipe coverers.

Dan Dowling, president of Local S6 of the Machinists union, which has approximately 3,400 members, said Friday morning that he had just received official notification of the layoff — the second in about a month.

Some of the employees affected are the same people laid off in August. Bath Iron Workssubsequently found new positions for all them, but Dowling said, “This will be their second time in the crosshairs.”

BIW spokesman Jim DeMartini confirmed the layoffs, and said the company would “work up until the last minute to try to place anybody we can into a job they’re qualified to fit into.”

The shipyard currently employs approximately 5,700 people.

Amid news of the layoffs, Bath Iron Works on Thursday learned it would receive a $13.3 million U.S. Navy contract modification to complete work on the deckhouse of the DDG-1000, the first of three Zumwalt-class stealth destroyers under construction at the shipyard.

But the new work does not affect the layoffs. Because the shipyard works on multiple ships simultaneously, an award for one phase of work does not affect workforce needs on ships in other phases of construction.

DeMartini said in August that such layoffs “reflect the typical fluctuation we see for specific trades throughout the course of the production cycle. We’re always looking to balance the work we have with the resources.”

The DDG-1000, the future USS Zumwalt, is “approaching a high state of completion,” DeMartini said.

The hulls of the three Zumwalt-class destroyers — a line of stealth warships since discontinued because of their cost — are being built at BIW. Ingalls Shipbuilding’s Composite Center for Excellence facility in Gulfport, Miss., was awarded contracts to build the deckhouses, helicopter hangar and launch missile shields for the first two Zumwalt-class ships out of composite materials.

But on Aug. 2, the Navy announced that BIW had secured a $212 million contract modification to build the third deckhouse — for the future USS Lyndon Johnson — out of steel.

The decision prompted Huntington Ingalls to announce earlier this month that it would close its composites center.

At 610 feet long and with 80-foot beams, the DDG-1000 destroyers are the largest destroyers ever built at BIW. The first cost an estimated $3 billion, although the second and third will cost less. Each will hold a crew of 158 including an aircraft contingent for the ship’s two helicopters.

The future USS Zumwalt is scheduled to be christened on Oct. 19 at BIW, with “initial operating capability” — fully operational with a trained crew and “ready to go into combat” — by 2016, DeMartini said.