The company plans to suspend shipments from the refinery during the construction, which is set to start in mid-September. The work will be completed by the end of the month.
The source said the amount of the volume reduction was not fixed, but a trader said the volume would be cut by up to 50% out of 30,000 mt/month of typical supply.
Idemitsu can increase supply from its 120,000 b/d Tokuyama refinery in western Japan to compensate for the drop at Chiba, the source added. Tokuyama refinery typically ships about 30,000 mt/month of bunker fuel.
Supply might tighten in H2 September as a result of Idemitsu`s cut, a trader said.