UPDATE 1-Taiwan Formosa to shut No. 3 unit even if No.1 stays offline

(Adds comments, RFCC turnaround)

SINGAPORE, July 27 (Reuters) - Taiwan's Formosa Petrochemical Corp will shut its No. 3 naphtha cracker in mid-August for a planned maintenance even if it fails to restart its No. 1 unit by then following another outage, its spokesman said on Wednesday.

Refinery runs are not affected for now and it will also stick to shutting down a gasoline-making unit for a planned maintenance which will affect its spot gasoline exports, he added.

"We are not sure when we can restart No. 1 at this point as investigations are still ongoing," said the spokesman.

"But regardless of when the No. 1 unit can resume operations, we will still go ahead and shut the No. 3 cracker," he said.

Asia's top naphtha buyer was to restart the 700,000 tonnes-per-year (tpy) No. 1 cracker in first-half August, after it was shut following a fire at a liquefied petroleum gas (LPG) pipeline on May 12.

Formosa suffered another setback on Wednesday morning after a fire damaged a power transmission network at Formosa Plastics complex and put the No. 1 cracker restart date on limbo again.

The fire, traders said, was at a hydrogen pipeline that belongs to a utility company.

The line provides energy to many units in the Mailiao complex where Formosa's petrochemical units and refinery are located.

REFINERY RUNS NOT AFFECTED FOR NOW

Formosa's spokesman said that runs at its 540,000 barrels-per-day (bpd) refinery is not affected for now.

"Our planned maintenance at the residue fluid catalytic cracker (RFCC) will not be affected," he said.

The 84,000 barrels-per-day (RFCC) is to be taken offline in early August for 40 days. It has another RFCC of the same capacity which will continue to running.

But Formosa will need to reduce the refinery runs to around 400,000 bpd during the 40-day maintenance at its RFCC, down from about 450,000 bpd currently.

"Gasoline term exports will not be impacted as those have already been allocated. But spot exports will be affected," he said.

Formosa exports an average of 210,000-240,000 tonnes of gasoline a month, of which about 30,000 tonnes is on spot basis.

It will skip exporting spot cargoes for July and August loading, but it was not immediately clear if there will be a cargo for September.

(Reporting by Seng Li Peng and Jonathan Standing in Taipei; Editing by Ed Lane)