Failed boltA panel of experts assembled by the MWRA blames last spring's catastrophic collapse of the main aqueduct feeding Boston on poorly constructed studs holding together a connection between two parts of the giant water pipe.
The failure of the aquaduct in Weston left much of the Boston area without potable water for several days.
In a report released today, the panel said cracked studs, inadequately protected from corrosion and subjected to greater than designed pressure gave way, leading to a sudden rupture of the coupling. It didn't help, the report adds, that rubber O-rings in the coupling were apparently glued in place with the equivalent of Super Glue, rather than using a factory vulcanization process.
While the stud material hardness was consistent with those specified for the coupling they exhibited characteristics that suggest poor fabrication. Cracks were present on essentially all of the thread "crowns." Additionally, cracks were present at many of the thread "roots." Upon further examination it was determined that the root cracks were located within 9 threads of the fracture surfaces. This location is consistent with the location of the highest stud load.
