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Brittle Bolts Prompt $1.5M Repair

Friday, March 27, 2015

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Hydrogen embrittlement of arm-sized bolts on a six-month-old London skyscraper has prompted a bolt-by-bolt review that has cost more than $1 million, according to the contractor performing the work.

Replacing the bolts on the Leadenhall Building (known locally as the "Cheesegrater"), the city's tallest skyscraper, has cost the UK’s biggest structural steel contractor £1 million (about $1.5 million) so far.

Severfield Group disclosed the costs of the program Monday (March 23) in a trading update.

Leadenhall Building
tbmurray / Creative Commons

Three bolts have fallen from the Leadenhall Building in London since November. An investigation has laid the cause of the failure to hydrogen embrittlement. The steel contractor reports it has spent $1.5 million on the replacement program.

Many of the 3,000 steel bolts on the building were ordered examined and replaced after three of them fractured and fell from the structure in just over two months, according to its developer, British Land.

The first and second bolts fell in November 2014. The third fell sometime before mid-January. The 734-foot tall building opened in September 2014.

An investigation concluded that the bolts had fractured due to “a material failure mechanism called Hydrogen Embrittlement,” the developer announced in January.

No injuries were reported in any of the incidents.

British Land did not say how many bolts will ultimately be replaced but maintains that the building's structural integrity has not been compromised. The bolts—which range from 20cm to 120cm long and have diameters of between 5cm and 7.5cm—connect the nodes on the megaframe, according to The Telegraph.

Bolt Replacement Program

The replacement program that Severfield is conducting with contractor Laing O’Rourke and structural engineers Arup was initiated as a “precautionary measure,” according to British Land.

construction of Leadenhall building
willrocks10 / Creative Commons

The 734-foot-tall Leadenhall Building, known locally as "The Cheesegrater," is the tallest structure in London. It opened in September 2014 after almost three years of construction.

The project on the 47-story building is expected to last until the end of the year.

Severfield said the parties involved were in discussions to determine the liability for the bolt replacement program, according to the update.

Severfield also said that the costs it has incurred were “exceptional” and should not affect the company’s profitability for the current year.

Severfield provided 18,000 tonnes of steel for the building in 2013, according to The Telegraph.

The steel contractor, based in Thirsk, North Yorkshire, was founded in 1978. The company’s portfolio includes stadiums, commercial office buildings, landmarks and industrial buildings.

Bolt Blues

The Cheesegrater is not the only structure battling bolt problems. Broken bolts nine feet long have been among the chief problems vexing the San Francisco-Oakland Bay Bridge since its 2013 opening.


California officials have had their own bolt problems on the San Francisco-Oakland Bay Bridge. Thirty-two massive bolts broke during construction of the bridge's eastern pier only days after crews started to tighten them.

Thirty-two bolts, also called anchor rods, popped loose in March 2013, just days after crews started tightening them.

Experts previously described the galvanized steel rods as "vulnerable," and the California Department of Transportation (Caltrans) had banned their use on other bridges because of the risk.

Investigations have mounted and repair estimates have run into the millions as officials try to resolve the problem bolts and other issues that have bedeviled the $6.4 billion project.



Tagged categories: Architecture; Commercial Construction; Contractors; Developers; EMEA (Europe, Middle East and Africa); Engineers; Health and safety; Quality Control; Steel

Comment from Tony Rangus, (3/27/2015, 10:40 AM)

Would be very interesting to know what country of origin manufactured the fasteners as well as the country of origin for the starting material.

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