By Daniel Trotta

HOUSTON, Sept 5 (Reuters) - Texas takes another step toward recovery from Hurricane Harvey on Tuesday when many residents return to work for the first time since the storm devastated the Houston area, killing around 60 people and putting tens of thousands into emergency shelters.

Many large Texas employers, universities and transit services are reopening or beginning full service on Tuesday after Labor Day, some for the first time since Harvey struck the state on Aug. 25.

Oil refineries, pipelines and shipping channels in the nation’s energy center have begun a gradual return of operations.

Exxon Mobil, Halliburton and Chevron are among the scores of Houston businesses reopening their doors to office workers. Texas A&M University in Corpus Christi and the University of Houston also are resuming classes Tuesday.

The storm first hit Corpus Christi in the south and traveled up the coast, dumping up to 51 inches (129 cm) of rain in places across the region and flooding homes and businesses.

Texas residents who fled to Austin, San Antonio and Dallas ahead of the storm returned to check on their homes as flooded streets drained.

In Houston, travel north and east of the city eased over the weekend and highways filled as more gasoline stations opened and supplies, while tight, proved adequate.

Exxon said its Spring, Texas, campus was unaffected by the heavy rains. But employees who need to work remotely are encouraged to do so, spokeswoman Suann Guthrie said.

Houston Metro, a regional transit provider, said it would open all its parking lots and rush-hour lanes on Tuesday.

Most roads have reopened but travel in some areas west of the city remains difficult. ConocoPhillips’ headquarters on the west side is closed until Sept. 11 due to flooded roads.

Houston’s school district, the seventh largest in the nation, also remains closed this week to repair flooded schools. The district has said about 75 of its 275 schools suffered major or extensive flood damage.

As Houston picked up the pieces from the devastation of Harvey, a new hurricane threat appeared, this time headed for the Caribbean islands, the U.S. East Coast and Florida.

Hurricane Irma was upgraded to a powerful Category 4 storm on Monday as islands in its path braced for its impact. Hurricane advisories were issued for territories that dot the West Indies, including parts of the Leeward Islands, the British and U.S. Virgin Islands and Puerto Rico in preparation for the storm.

ENERGY SECTOR

In Texas, shipping channels, oil pipelines and refineries restarted some operations on Monday and authorities lifted an evacuation order for the area around a once-burning chemical plant.