(Reuters) - The United Steelworkers union told U.S. refinery workers to prepare to offer safe and orderly refinery shutdowns before a strike that could begin as early as 12:01 a.m. Wednesday, sources familiar with the union's preparations said Sunday.
Most refiners are expected to reject the shutdown offer and begin assigning temporary replacement workers to operate refinery units if USW-represented workers walk off their jobs.
Talks between the union and oil company representatives for a new three-year national contract were continuing on Sunday.
The notice to prepare for a strike does not mean a work stoppage will take place, the sources said.
USW spokeswoman Lynne Hancock declined to discuss the message.
We don't negotiate in the media, Hancock said.
Lead refiner negotiator Shell Oil Co said on Sunday morning that it was optimistic about the talks.
Shell is optimistic that a mutually satisfactory agreement can be negotiated with the USW, said Shell spokeswoman Emily Oberton.
About six percent of U.S. refining capacity was expected to shut down when workers walk off their jobs, sources familiar with refiners' plans have said. Another five percent is expected to shut if a strike lasts up to three months.
The last nationwide strike by refinery workers was in 1980 and lasted three months.
The Steelworkers represent workers at refineries accounting for almost two-thirds of national refining capacity. Because not all contracts between local unions and refiners expire on February 1, only about a third of U.S. capacity would be immediately affected by a strike, if one takes place.
Most refiners plan to continue operating their refineries using salaried employees trained to operate production units.
The shutdown preparation notice comes one day after the union said a strike at one or more locations was becoming more likely due to the lack of a more substantive response from the industry after nearly two weeks of talks.
One version of the shutdown preparation message obtained by the Galveston County Daily News newspaper and posted on its Web site read: All locations should be prepared to make arrangements with your respective employers to offer a safe and orderly shutdown of your facility if and when you are instructed to do so.
Messages like the warning on Saturday and the shutdown preparation notice have not been sent out in the previous three rounds of negotiations with oil companies for a contract.
(Editing by Bernard Orr)