Weak Rivets lead to an tragedy
2008-08-21

How do you fasten something when you do not have access to the back of the item you are fastening to? Sometimes you just cannot reach, or it is hidden under machinery and simply unaccessible. Blind Rivets are multi-piece rivet assemblies, capable of being installed from one side of the workpiece. Traditionally, blind rivets were used on aircraft leading edges, trailing edges, and close out areas which are limited to access to one side of the structure. Current blind rivet usage has expanded to many additional areas of the aircraft in an effort to decrease labor expense and to address the ergonomic issues of solid riveting. This is the beauty of Blind Rivet POP® technology. "Blind Setting" allows for fastening from the front, and the POP® line of products has solved numerous industrial problems since it's creation. Researchers have discovered that the builder of the Titanic struggled for years to obtain enough good rivets and riveters and ultimately settled on faulty materials that doomed the ship, which sank 96 years ago Tuesday. The builder’s own archives, two scientists say, harbor evidence of a deadly mix of low quality rivets and lofty ambition as the builder labored to construct the three biggest ships in the world at once — the Titanic and two sisters, the Olympic and the Britannic. For a decade, the scientists have argued that the storied liner went down fast after hitting an iceberg because the ship’s builder used substandard rivets that popped their heads and let tons of icy seawater rush in. More than 1,500 people died A rivet is a mechanical fastener. Before it is installed it consists of a smooth cylindrical shaft with a head on one end. The end opposite the head is called the buck-tail. On installation the rivet is placed in a pre-drilled hole. Then the tail is "upset" (i.e. deformed) so that it expands to about 1.5 times the original shaft diameter and holds the rivet in place. To distinguish between the two ends of the rivet, the original head is called the factory head and the deformed end is called the shop head or buck-tail. Because there is effectively a head on each end of an installed rivet it can support tension loads (loads parallel to the axis of the shaft); however, it is much more capable of supporting shear loads (loads perpendicular to the axis of the shaft). Bolts and screws are better suited for tension applications. Fastenings used in traditional wooden boat building like copper nails and clinch bolts work on the principle of the rivet but they were in use long before the term rivet was invented. So, where they are remembered, they are usually classified among the nails and bolts respectively. The scientists say the Titanic’s troubles began when its ambitious building plans forced Harland and Wolff to reach beyond its usual suppliers of rivet iron and include smaller forges, as disclosed in company and British government papers. Small forges tended to have less skill and experience. Adding to the problem, in buying iron for the Titanic’s rivets, the company ordered No. 3 bar, known as “best” — not No. 4, known as “best-best,” the scientists found. Shipbuilders of the day typically used No. 4 iron for anchors, chains and rivets, they discovered. So the liner, whose name was meant to be synonymous with opulence, in at least one instance relied on cheaper materials. Many of the rivets studied by the scientists — recovered from the Titanic’s resting place two miles down in the North Atlantic by divers over two decades — were found to be riddled with high concentrations of slag. A glassy residue of smelting, slag can make rivets brittle and prone to fracture.