Butler Hospital’s unionized staff yesterday ratified a new three-year contract that includes annual pay raises and limits the use of “travel” nurses, whose use has been a nettlesome factor for the psychiatric center’s employees.

Members of the union representing nearly 300 nurses, mental-health workers and other employees had voted to strike if their contract demands were not met. The members of District 1199, the New England Health Care Employees Union/SEIU picketed the hospital Monday to call attention to the contract issues. The nurses had been working under an extension of a three-year contract since March 31.

A key sticking point was the hospital’s use of travel nurses, who work for staffing agencies. The union accused hospital management of using the temporary nurses to fill vacancies, rather than hiring permanent workers.

But just before midnight Wednesday, union negotiators reached a tentative agreement with management to keep staff members working. Staff members voted throughout the day yesterday, ultimately approving a new three-year contract, according to a hospital statement.

The new contract includes annual pay raises of 4 percent, 4.25 percent and 4 percent, respectively. The pact limits the use of contracted staff and excludes mental-health workers from having to work mandatory overtime.

“We stuck together and ensured that the hospital addressed our concerns about the dangers of travel nurses — such as medications errors and unfamiliarity with the type of care our patients need,” said Jay Drapeau, a member of the union’s negotiating committee.

The 117-bed private psychiatric and substance-abuse treatment facility has used travel nurses, according to a hospital spokeswoman. Hospital management says the use of travel nurses, who are contracted through temporary staffing agencies, is rare but necessary.

Care New England, the organization that operates Butler Hospital, uses travel nurses in at least one of its other facilities — Kent Hospital in Warwick. Care New England also includes Women & Infants Hospital and Care New England Home Health.

The new contract maintains free Blue Chip HMO coverage for some workers. In exchange, participating workers must complete either an annual physical or a health-risk assessment and participate in at least two health or wellness programs annually.

“We believe that the new contract is fair and equitable agreement for the staff and enables the hospital to preserve its economic stability while continuing to provide the highest standard of patient care,” said Dr. Patricia Ryan Recupero, the hospital’s president and chief executive officer.

A union spokesman could not be reached for comment yesterday.

pgrimald@projo.com