UPDATE 1-Thai PTTCH plans 13-day olefins plant shutdown

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BANGKOK, Jan 25 (Reuters) - PTT Chemical PCL PTTC.BK, Thailand's largest olefins maker, said on Friday it planned to shut down its I4-1 olefins plant for maintenance for 13 days from Jan. 31-Feb 12.

The shutdown would cut production by 29,000 tonnes, or 1.7 percent, at the company which has an annual capacity of 1.713 million tonnes, it said in a statement.

PTTCH, a flagship in the olefin petrochemical business of PTT PCL PTT.BK, produces ethylene and propylene, together called olefins, petrochemicals used to make plastic pellets, especially for the packaging industry.

In November, the company said it planned to shut down its propylene unit for 30 days in the second quarter of 2008 and close its mono ethylene glycol (MEG) plant for 35 days to expand capacity in the third quarter.

Its high density polyelylene (HDPE) plant, run by its Bangkok Polyethylene unit, will be shut for 30 days in the third quarter.

PTTCH uses natural gas for about 75 percent of its feedstock and naphtha provides the rest, but naphtha prices are used as reference for its feedstock costs.

PTTCH shares fell 5 percent at 92.50 baht on Thursday, when the main Thai index .SETI dipped 1.63 percent. (Reporting by Khettiya Jittapong; Editing by Michael Battye)