UPDATE 1-Trans Mountain expects first ship to load from expanded pipeline in second half of May

(Adds details on pipeline project, comment from Trans Mountain in paragraphs 4-7)

By Nia Williams

April 23 (Reuters) - The first ship carrying crude from the expanded Trans Mountain pipeline is expected to load at the Port of Vancouver in the second half of May, the company building the project said on Tuesday.

The expanded pipeline will carry an extra 600,000 barrels per day (bpd) of oil from Alberta to Canada's Pacific coast and is set to start transporting crude on May 1.

Final line fill will be completed in early May, Trans Mountain said in an email.

The C$30.9 billion ($22.62 billion) expansion project, bought by the Canadian government in 2018 to ensure it went ahead, has struggled with years of regulatory delays and cost overruns.

Canadian oil producers are keenly anticipating its opening, which will open up access to export markets on the U.S. West Coast and Asia and is expected to narrow the price discount on Canadian heavy crude versus U.S. benchmark oil.

Westridge Marine Terminal in the Port of Vancouver, where the pipeline terminates, will have three berths able to load vessels with oil, Trans Mountain said. The dock has a maximum capacity of 630,000 bpd, or 34 partially laden Aframax-sized tankers a month.

"On average, we anticipate one empty tanker in, one partially laden tanker out every day with variability throughout the year," a Trans Mountain spokesperson said. ($1 = 1.3660 Canadian dollars) (Reporting by Nia Williams in British Columbia; Editing by Jonathan Oatis and Jamie Freed)