The rivet holes were evidently punched and not subsequently reamed, likely to save time. The connection between the bottom of ring 1 and the bottom of the tank was made through a 4-inch by 4-inch by 0.75-inch angle. All horizontal joints were connected by lap joints with a single row of rivets. The vertical joints in the remaining rings were made by lap joints using triple rivets in rings 2 and 3 and double rivets in rings 4 through 7. The vertical joints between the pieces in the first course were made with double butt joints with a triple row of rivets on each side of the joint in a diamond pattern (Figure 4). The riveted construction was 90 feet in diameter, 50 feet tall, made of open hearth steel varying in thickness from 0.67 inch for the first ring at its base to 0.31 inch for the seventh ring at the top. The tank was designed to contain 2.5 million gallons of liquid and erected on a very short schedule during the winter of 1915. Its distant location was considered a key piece of evidence that an explosion had occurred. The last fill to near capacity occurred two days prior to the failure.Ī 6-ton piece of the tank that included part of the manhole was found the furthest from the tank, about 200 feet, in the playground in the right foreground of Figure 1. The tank had been filled 29 times, but only four times to near maximum capacity. The weather conditions at the time of the failure were partly cloudy, about 40 ☏ (4 ☌) with a wind of at most 24 mph, absent of snow or rain. Figure 3 is a schematic of the structures that were adjacent to the tank, as well as the approximate initial locations of some of those killed when the tank burst. Figure 2 is a photograph taken at the disaster site. Photo: Courtesy of Bill Noonan, Boston Fire Department Archives.Īnalysis of the accident scene began immediately after the failure. Figure 2: A large piece of the tank pushed against the elevated railway.

An excellent account of the general circumstances surrounding the accident, with particular attention to the historical and social aspects at the time - anarchists were blamed by some for setting off an explosion in the tank - is given by Stephen Puleo (2003). Organizations carried out large-scale tank explosion tests and wide panel fracture tests that included a replica manhole from which nearly everyone agreed the fracture initiated. The many experts included several from MIT and Harvard, split about evenly between sides. The case was, without doubt, an expensive one. (Dorr, of the law firm Hale and Dorr, was the named plaintiff who had his house damaged from the tank failure.)

Abundant information is available on the accident, largely in the form of transcripts for the case of Dorr vs. The first fill occurred in February 1916, almost three years before the end of WWI. Figure 1 shows a photograph of the imposing tank a few months before the failure. It was situated close to the harbor near Copp’s Hill Burying Ground, Boston’s second oldest graveyard and a popular tourist attraction today. Industrial Alcohol, was used to store molasses shipped from the Caribbean for the production of a munitions ingredient. The incident resulted in a three-year trial in which the court auditor found the operator of the tank liable, but was frustrated by more than 20,000 pages of conflicting testimony from dozens of expert witnesses. The spill killed 21 people, drowned several horses, and caused substantial structural damage to nearby buildings and the adjacent elevated railroad. 15, 1919, at about half past noon, a tank containing 2.3 million gallons of molasses burst, sending a wave of sticky liquid through the streets of the North End of Boston. A structural and metallurgical perspective of design practices at the time and fracture evidence based on current understanding.

Great molasses flood in boston