US stocks of propylene for non-fuel use in the week that ended November 3 rose 51,000 barrels to 2.573 million barrels, Energy Information Administration data showed Wednesday.
Inventory levels currently are 1.087 million barrels below where they were a year ago, the data showed.
US refinery run rates rose 1.5 percentage points to 89.6% last week, EIA data showed.
The utilization rate was 2.5 percentage points higher than the year-ago week, the EIA data showed.
In the spot market, US polymer-grade propylene was assessed stable Wednesday at 46.25-46.75 cents/lb FD USG for November deliveries.
US spot refinery-grade propylene remained stable at 34-34.5 cents/lb FD USG on a three- to 30-day basis.