A view of the massive bolts that secure subsea oil wells. U.S. regulators and oil-field… General Electric Co. GE 0.25 % , oil drillers and U.S. regulators are scrambling to determine why massive bolts used to connect subsea oil equipment keep failing, prompting costly shutdowns and raising safety concerns about hundreds of wells in the Gulf of Mexico. Safety regulators at the Department of the Interior began investigating the matter in 2013, officials said in an interview, after a GE oil-exploration equipment business issued a global recall for faulty bolts on one of its components. The bolts have corroded and sometimes snapped, raising the possibility of a major oil leak. But the U.S. investigation and two recent bolt failures convinced regulators and industry officials that the problem goes beyond GE and its blowout preventers—safety gear used to halt oil-and-gas flow during a well emergency. “This is what we view […]