BATH – Bath Iron Works served notice Friday to its largest union that it plans to lay off an additional 37 production workers, the second round of job losses in two weeks, as a union leader expressed concerns about future cuts.

The affected workers include 28 pipe fitters and nine pipe coverers with more than 17 years of seniority at the shipyard, said Mike Keenan, president of Local S6 of the Machinists Union.

The announcement came on the final workday for 30 painters and cleaners, who received their layoff notices last week. The shipyard has more than 3,400 production workers.

In both rounds of layoffs, Keenan said, management departed from past practice of providing prior consultation with the union on alternative measures that could be taken to preserve jobs.

The new approach “almost looks intentional, like it has a little malice to it,” he said.

Noting that the layoffs come as his members have been working overtime, the union president said BIW has apparently decided that it’s cheaper to have them put in the extra hours than to keep more workers on the payroll.

Shipyard spokesman James DeMartini could not be reached, and his office said there was no one else available prepared to comment.

Keenan said the layoffs have created uncertainty among his members and tension between labor and management.

“The morale in the shipyard has plummeted. Other individuals are frightened that they’re next,” he said. “There’s no sense of job security anymore.”

Keenan said the union’s requests to see BIW’s staffing plans have come up empty: “They’re being guarded like they’re the blueprints to Fort Knox.”

The shipyard has emphasized the need to promote efficiency as construction of the Navy’s Arleigh Burke destroyers winds down and Bath prepares for the DDG-1000 Zumwalt class program that will replace it.

House and Senate conferees on Thursday agreed to fund construction of two DDG-1000 ships, appropriating $2.6 billion for the production of a lead ship at both Bath and Ingalls beginning next year.

Keenan said union officials have been in contact with members of the Maine congressional delegation to express concern about the yard’s staff plans during the transition.

The union official said he feared BIW could lose more work to rival Northrop Grumman Ingalls in Mississippi as a result of bartering over which yard will get to build specific sections of the new ships.

Keenan said he was worried that Bath was prepared to subcontract the central portion of the ships, which contains the most high-tech combat spaces, in return for building the fore and aft sections.

“BIW would say it’s an even swap, but no, it’s not,” he said, suggesting that the impact on jobs could be devastating.