(Adds FEMA not commenting, details on the plant, other plants closed, member of Congress saying evacuation in progress)
Aug 29 (Reuters) - A chemical plant in southeast Texas is evacuating its remaining workers on Tuesday amid the risk of an explosion after Tropical Storm Harvey knocked out power and flooding swamped its backup generators.
Arkema SA said in a statement the situation at its Crosby, Texas, plant "has become serious."
The plant has been hit by more than 40 inches (102 cm) of rain and was heavily flooded and has been without electric service since Sunday. Back-up generators have largely been inundated with water, the company added.
The key issue is maintaining refrigeration for chemicals on site, which are stored at low temperatures. The plant lost refrigeration when backup generators were flooded and then workers transferred products from the warehouses into diesel-powered refrigerated containers.
The company said some refrigeration of back-up containers has been compromised because of high-water levels and the company is monitoring temperature levels remotely.
"While we do not believe there is any imminent danger, the potential for a chemical reaction leading to a fire and/or explosion within the site confines is real," the company said.
Arkema is working with the U.S. Department of Homeland Security and the state of Texas to set up a command post near the site.
U.S. Representative Ted Poe, a Texas Republican, wrote on Twitter that the Crosby plant "is in danger of fire/explosion. The local area is being evacuated. Stay out of area."
Harvey, which came ashore in Texas last week as a powerful Category 4 hurricane, has caused catastrophic flooding.
The Federal Emergency Management Agency referred questions to Texas authorities, which did not immediately respond.
The Arkema plant in Crosby that produces organic peroxides has been closed since Friday but has had a skeleton staff of about a dozen in place. Other chemical plants have also shuttered production in Texas because of the hurricane.
Anglo-Swiss chemicals firm Ineos Group Holdings SA said it has been forced to shut down facilities in Texas -- Chocolate Bayou Works and Battleground Manufacturing Complex, and INEOS Nitriles' Green Lake facility are following hurricane procedures and are temporarily shut down, spokesman Charles Saunders said.
Huntsman Corp said it has closed six chemical plants in Texas, along with its global headquarters and advanced technology center in Texas. (Reporting by David Shepardson in Washington; Additonal reporting by Jarret Rensaw in New York; Editing by Peter Cooney and Lisa Shumaker)