RPT-Southeast Texas refineries preparing for frigid spell

(Repeating story from Wednesday)

HOUSTON Jan 6 (Reuters) - A spell of unusually frigid weather is expected to envelop southeast Texas from Thursday through Sunday, prompting area refineries to take inclement weather precautions.

"In simple terms, it is like winterizing the plumbing of a house," said Scott Dean, spokesman for BP (BP.N) (BP.L), regarding the company's 475,000 barrel-per-day (bpd) refinery in Texas City, Texas.

"Examples include checking insulation around pipes, adding extra sources of heat to lines and instruments that are vulnerable to freeze-ups and maintaining flow of liquids through piping," Dean said on Wednesday.

The National Weather Service issued a hard freeze warning effective from 9 p.m. CST Thursday through 9 a.m. Sunday, meaning temperatures below freezing are likely.

"An Arctic cold will race southeast Texas early Thursday morning," the weather service said. As Arctic high pressure settles over the U.S. southern plains, "cold air will remain entrenched over all of southeast Texas."

Refineries north of the Gulf Coast typically endure cold spells each winter, but those in south Texas rarely face sustained frigid temperatures. Debby Helvy, a meteorologist with the National Weather Service Houston-Galveston, said the last time southeast Texas experienced sub-freezing temperatures for three days was Dec. 22-24 in 1990. The longest stretch for such temperatures was 121 hours in January and February 1951, she said.

Kevin Allexon, spokesman for Exxon Mobil Corp (XOM.N), said the company prepares its 562,500 bpd refinery in Baytown, Texas, the largest in the U.S., as well as its 348,500 refinery in Beaumont, Texas for winter weather every year just as they undergo preparations for hurricane season.

Valero Energy Corp (VLO.N) spokesman Bill Day said the same for Valero's Gulf facilities, including its 245,000 bpd refinery in Texas City and its 145,000 bpd plant in Houston.

"In general, refineries are built to operate around the clock in all but the most extreme weather conditions," he said. (Reporting by Kristen Hays)