Formosa Petrochemical Corp. plans to restart a residue processing unit that was shut Sept. 2 at its Mailiao refining complex. A suspected flaw in piping design at the 80,500 bpd No. 1 residue desulfurization unit is being corrected. Formosa halted its 80,500 bpd No. 2 residue desulfurization unit after a fire on July 25. The Mailiao refinery has three crude distillation units, each able to process 180,000 bpd. Formosa Petrochemical shut the 540,000 bps refinery for safety reasons after an oil leak triggered a blaze at the No. 2 residue desulfurization unit. The company is using about one-third of its crude refining capacity, with one crude unit still shut and the other two running at half capacity.