Article Photos: Feds: Ruptured W.Va. pipe may have been corroded 4/4

This image provided by the National Transportation Safety Board shows an NTSB investigator at the site of a gas line explosion in Sissonville, W. Va., Wednesday Dec. 21, 2012. Federal regulators say there have been 20 "significant" pipeline incidents involving deaths, injuries or major property damage in West Virginia in the last decade.  (AP Photo/National Transportation Safety Board)