Documents released by Caltrans show that the contractor which supplied the bolts that snapped on the Bay Bridge in March had problems dating back to 2008.
The anchor rods that in March snapped on the new Bay Bridge were identified for testing by Caltrans four years ago, according to reports.
The saga of the rods -- 17- to 24-foot long, three-inch wide steel bolts that tie together the bridge deck and pier near the new $6.4-billion bridge's main tower -- began well before 32 of the 96 rods broke when tightened in March, according to the Contra Costa Times.
First, they were delivered late, the newspaper reported. And no less than "three" times did "steel parts supplied by Ohio-based manufacturer Dyson Corp. and its subcontractors" fail to meet Caltrans's specifications, the newspaper reported.
Caltrans refused to comment to the newspaper Tuesday. The agency has a meeting scheduled with a member of the state Legislature, where questions are expected to be answered, the newspaper reported.
The rods were heat-treated twice, after a subcontractor "lost the paperwork" related to the first strength test in 2008, the newspaper reported. Metallurgists say that reheating can make the bolts weaker.
Dyson Corp. had four subcontractors that "failed" Caltrans site visits for quality or documentation shortfalls, the newspaper reported.
The rods snapped, Caltrans believes, because they became brittle due to the presence of hydrogen in the high-strength steel. It's possible that water used in a "magnetic particle testing" process led to the "embrittlement," the newspaper reported.
The rods which broke were not so tested, however.
It's not yet certain exactly what caused the rods, which are currently covered in pavement and cannot be removed from the bridge, to fail.