WASHINGTON - When British Petroleum (BP) shut down a vital oil pipeline, the company blamed "unexpectedly severe corrosion" in transit pipes. Yet only five months ago, BP's aging pipeline created the largest-ever oil spill on Alaska’s North Slope. Federal regulators blamed the spill on "internal corrosion" and said in some areas the walls of the pipes were so corroded they were almost paper-thin. So critics and industry experts say the latest problem was hardly a surprise. "I think this was predictable and preventable," says Phil Flynn, an energy analyst with Alaron Trading Corp. In fact, allegations about BP's maintenance practices...