Indian officials are blaming unexpectedly “rapid corrosion” for the collapse of a massive silo that injured dozens of people this week—the same claim recently made by Quebec officials for failing to flag severe corrosion that now threatens a major bridge.
The roof of the steel-frame silo collapsed Monday (Feb. 20) at the Indian Farmers Fertilizer Co-operative Limited (IFFCO) plant in Paradip, a major seaport town on the Bay of Bengal.
|Rescue workers search the wreckage of a massive fertilizer silo that collapsed Monday in a seaport town in India.|
Casualty reports varied, but about 27 people were believed injured, 11 of them seriously, when the steel-frame structure crumbled, unleashing about 12,000 tons of fertilizer material.
Many Feared Trapped
“Many more are feared trapped inside the huge structure,” a police official told the Press Trust of India (PTI). “The structure, made of steel frame and asbestos, has complete[ly] collapsed and the rescue operation is on.”
The structure is 150 meters (nearly 500 feet) long, 50 meters (about 164 feet) wide and 27 meters (88.5 feet) tall.
No deaths have been reported.
As the rescue operation continued, the cooperative’s Executive Director, M.R. Patel, defended the structure’s maintenance. Patel said the steel frames had been painted regularly. He blamed the sudden collapse on “rapid corrosion in view of its proximity to the sea.”
|Local officials blamed unexpectedly rapid corrosion of the seaside structure for the collapse.|
However, District Superintendent of Police S. Devdutt Singh told IANS, “It was an old structure.” Fortunately, Singh added, “It collapsed during the tiffin [lunch] break, when there was thin attendance.”
Canadian Bridge Corrosion
Runaway corrosion was also claimed in September when the Quebec government released an inspection report detailing unexpectedly severe degradation that forced the abrupt closure of part of the Mercier Bridge last summer.
The twin-span bridge over the St. Lawrence River and Seaway opened in 1934—a second span was built in the 1960s—and carries nearly 30 million vehicles per year. The original part of the bridge is run by Quebec; the newer span, by the federal government.
The bridge has not been painted for decades, but a massive redecking project—the largest bridge rehabilitation project ever undertaken in Canada—began in 2009.
Gusset Plate Deterioration
Meanwhile, however, a June 2011 inspection found corrosion on the bridge was so advanced that some bridge parts were perforated and deformed. In particular, the findings note severe erosion of 10 gusset plates—the same bridge component that catastrophically failed on the I-35 Bridge in Minneapolis in 2007, causing the bridge to collapse into the Mississippi River.
Of 346 Mercier bridge parts inspected, 86 rated a 1— “incapable of performing required task.”
|Part of the Mercier Bridge was closed after an inspection found severe erosion in the gusset plates—the same component blamed for the 2007 collapse of the I-35 Bridge in Minnesota.|
Three days after receiving the report—but six months after the inspection was completed—Quebec’s Transport Ministry banned most traffic from the bridge.
Transport Minister Pierre Moreau defended the government’s maintenance of the bridge, saying that the deterioration had progressed “at a faster rate than what was expected” and could not have been caught earlier.
However, civil engineers hired by news outlets disputed the claim and said inadequate earlier inspections were more likely responsible.
“There is nothing called ‘rapid rusting’ or ‘rapid corrosion,’”Adel Hanna, a professor of structural engineering at Concordia University, told the Montreal Gazette.
“It is politically motivated to explain to the public that ‘Oh, look, all of a sudden we have this,’” Hanna said. “It doesn’t work this way. I categorically reject this statement. There is a gradual [deterioration], yes. But not all of a sudden.”
Saeed Mirza, a structural engineering professor at McGill University, agreed. "There is nothing called rapid corrosion," he told the Gazette.
“The deterioration due to corrosion of steel will be gradual,” he said. “In this case, it will corrode from the surface, and normally it would slow down a bit after it has gone into the steel. But it would no longer escalate. Unless, of course, the environment changes drastically. So the short answer is steel sections on a bridge cannot deteriorate rapidly, as is stated by the ministry.”
The last general inspection of the bridge was commissioned in 2006 by Jacques Cartier and Champlain Bridges Inc., which owns the Mercier’s federal side. That report recommended 37 repairs totaling close to $32 million, including nine classified as priority A, meaning they were “necessary to maintain the integrity of the system’s structure and of its auxiliary components,” the newspaper reported.
Blanchardb / Creative Commons
|The original part of the Mercier Bridge, which dates to the 1930s, is maintained by Quebec. The second span, built in the 1960s, is federally run. Critics say Quebec has not kept up with its part.|
The federal government reinforced about 50 gussets in 2008, and the bridge company says it has spent $74 million since 2006 making repairs. Quebec, on the other hand, “long criticized for neglecting transportation infrastructure, decided not to do work on its gussets,” the Gazette said.
According to reports released by the Quebec government, only part of the bridge was inspected annually between 2007 and 2011. For the 2008 inspection, Transport Quebec hired three different engineering firms, “each in charge of a group of spans” and each with its “own method of organizing information,” Montreal Gazette reporter Roberto Rocha blogged.
Still, neither the 2007 nor the 2008 inspection report raised serious concerns about the bridge’s condition, civil and structural engineer Normand Tétreault told the Gazette after reviewing the records. The reports noted “no huge problems.” They rated the paint as “acceptable to critical” and recommended repainting.
Hanna, the structural engineer, was among those criticizing the Quebec government’s handling of the situation.
“We should see the situation clearly from one report to another,” he told the Gazette. “When they close it all of a sudden, I think that they failed their responsibility. If this bridge collapsed—this is a major bridge in Montreal—it would have killed a few hundreds of people.”