PERSPECTIVE: Did Weak Rivets Allow Titanic Hull to Unzip?

Jason Sandefur

Editor”s Note: Articles in Media Spotlight are excerpts from publications or broadcasts that show the industry what the public is reading or hearing about fasteners and fastener companies.
Did “weak rivets” allow the Titanic hull to “unzip” when the famous ship struck an iceberg on April 15, 1912?
“The liner would have survived the collision for long enough for most of, or even all, its passengers to be rescued had it not been put together with weak rivets that caused its hull to “unzip” on impact with the ice,” The Times of London reported.
Could a rescue ship which arrived within two hours after the Titanic sank have saved the 1,523 people who died?
“The most celebrated disaster in maritime history owed as much to substandard rivets as it did to the iceberg,” reporter Mark Henderson wrote.
In an article headlined “Tiny flaws that Caused a Titanic Waste of Life,” Henderson noted that “faulty construction has long been suspected as having contributed to the loss.” The initial experiment to “mimic what happened to the rivets that held the hull together has shown that they could not have withstood the collision.” That weakness allowed five or six of the ship”s watertight compartments to flood, causing the ship to sink in just over two hours. Stronger rivets might have delayed the sinking until rescuers arrived.
Two metallurgists, Tim Foecke of the U.S. National Institute of Standards & Technology and Jennifer Hooper McCarty of Oregon Health & Science University, developed the rivet theory after examining 48 popped rivets from the wreck.
Foecke and McCarty found that the wrought iron contained 9% slag a glass-like substance that adds strength at concentrations of 2% to 3% but weakens metal at higher levels.
Foecke commissioned UK blacksmith Chris Topp to produce rivets to the same specifications. The rivets were installed in steel plates and bent in the laboratory. The rivet heads popped off at loads of about 4,000kg (9,000lb). With the right slag content, they should have lasted until a load of about 9,000kg.
Even a few rivets failing could have led to the unzipping. As faulty rivets popped, “a domino effect ensued, distributing the increased loads to other rivets until the damaged seams began to open up,” Foecke told the Times.
Foecke”s analysis of metal recovered from the wreck has also overturned another popular theory about the sinking: that the ship”s hull ruptured as it was made from brittle steel. Mechanical tests “show adequate fracture toughness in the steel at ice-water temperatures, fairly close to steels used to build bulk-carrier ships today,” Foecke said. “The brittle steel theory does not stand up to close scrutiny, and is wrong.”
The iceberg did not cause a gash. A series of bouncing impacts popped open rivets along the bow, creating small openings. Foecke told the Times that witnesses recalled “water trickling through the ship”s side, not enough to be considered continuous, but a steady pour on to the deck floors. This is consistent with the notion of seams that steadily bulged open as rivets failed, rather than a gaping hole produced by plate fracture, but it doesn”t explain how so much water filled the ship so quickly.”
Editor”s Note: One FastenerNews.com subscriber responding to the November 13, 2006, posting commented: “I wonder if the rivets were the culprit, or, was an overzealous, short-sighted purchaser for the ship building company at fault?” Jeff Walters of Cleveland-based Master Products Company asked. “My money is on the latter of the two.” \ �2006 FastenerNews.com