Citing threats from union pickets, state grain inspectors are refusing to enter United Grain Corp.’s export facility at the Port of Vancouver, prompting the company to shut down the largest grain elevator on the West Coast. The latest development in the bitter, 17-month-long standoff between United Grain, and the International Longshore and Warehouse Union has triggered a new round of finger-pointing, with no solution in sight.“For all practical purposes, we’re shut down,” Pat McCormick, spokesman for the Pacific Northwest Grain Handlers Association — whose membership includes United Grain — said Thursday.It’s not the first time the company’s operation has experienced interruptions. And shippers may still use other grain terminals in the region. But the full stop of United Grain’s operation has prompted national and state agricultural and export interest groups to call on U.S. Secretary of Agriculture Tom Vilsack to restore inspections by directing federal personnel to take over the work. The refusal of inspections by the Washington state Department of Agriculture creates “an extremely troubling precedent that will cause irreparable damage to the integrity and reliability of the nation’s … grain inspection system,” the groups wrote to Vilsack in a July 14 letter.It’s unclear whether state inspections will restart or if federal checkups will be ordered. McCormick said United Grain is “pursuing all directions” to restore inspection services.