The diversified Bergen-based owner has acquired the 12,400-dwt stainless-steel Stolt Jasmine (built 2005) from Stolt-Nielsen.
Brokers say the ship is worth some $15m.
Seatrans director Jan Henrik Johansen confirms the deal but says the transaction is more complicated. He declines to provide further details.
Last year, Seatrans sold the 6,900-dwt chemical tanker Trans Arctic (built 1991) to Russian interests for some $4.2m.