The International Longshore and Warehouse Union Tuesday is expected to announce the results of votes taken by its local units on whether to ratify a tentative contract agreement with Northwest grain terminal operators.The Longshore union and the Pacific Northwest Grain Handlers Association, whose membership includes United Grain Corp. at the Port of Vancouver, reached a tentative labor accord earlier this month, subject to approval by union members.The vote comes when an old battle between the Longshore union and the Port of Portland has flared up again. The port disclosed on Friday that it will return refrigerated container work at its Terminal 6 to the International Brotherhood of Electrical Workers members in 30 days. Last December, Oregon Gov. John Kitzhaber had brokered a deal to move those positions from the electrical works union to the Longshore union, breaking a long and bitter impasse between the two unions.Electrical worker union members had performed the work since 1974, but the Longshore union claimed jurisdiction over the work, which involves the plugging and unplugging of refrigerated containers by a small number of workers. Now that the work is being done by the Longshore workers, the port said in a statement that low productivity “has resulted in recent downtime and delays that threaten the ability of the facility to meet the needs of regional and global businesses.” The port said the reassignment of tasks to the Longshore union has resulted in significant cost increases at Terminal 6. Port of Portland executive director Bill Wyatt said that the issue is critical because the Hanjin shipping line is actively evaluating whether to continue its calls to Portland, with productivity as one of the factors in its evaluation. Wyatt said Kitzhaber fully supports the port’s to shift the jobs back to the electrical workers.