The 1919 Boston Molasses Flood: 21st Century Engineering Analysis Identifies New Flaws

A modern engineering analysis of the Boston storage tank that ruptured and released a flood of molasses into streets in 1919 discovered design flaws that led to the disaster. Did the early 20th century engineers have the knowledge base necessary to identify the problems with the storage tank before it failed?

On January 15, 1919, a gigantic steel storage tank ruptured and released a tidal wave of 2.3 million gallons of molasses that submerged the streets of Boston’s North End. This bizarre flood claimed 21 lives left 150 people injured, and destroyed numerous buildings. Three years after this disaster, a court found the owner of the tank, U.S. Industrial Alcohol, liable for $300,000 in damages. The court based its ruling on an auditor’s report indicating that carbon dioxide built up in the tank and eventually led to its rivets failing. Does this theory withstand the scrutiny of a modern engineering analysis?

New Study Finds Multiple Causes of the Storage Tank Failure

Ronald Mayville, a structural and metallurgical engineer, took an interest in exploring possible reasons for the failure of the molasses storage tank. The results of his investigation, published in Civil and Structural Engineer News, indicated the storage tank failed due to the following:

• • The steel wall of the tank were half the thickness needed to withstand the pressure of the fluid inside the tank when full.
• • The composition of the steel include magnesium, which made the metal too brittle to use as a large storage vessel.
• • The tank failed due to a fracture in the steel surrounding a rivet hole located above a 20-inch manhole. The stress of the fluid inside the tank further weakened the structure to the point of catastrophic failure. Today’s building standards require reinforcement of the metal surrounding rivet holes.

While metallurgic science in the early 20th century had not advanced to the point the engineers would have known about the effects of magnesium on the strength of the steel, Mayfield asserts they should have recognized the wall of the tank were 50 percent thinner than what was required. These findings, along with a review of historic records, suggests the presence of critical, yet preventable, design and construction errors that predisposed the storage tank to fail. What were the other flaws? Based on the engineering standards of practice in the early 20th century, how could this disaster been prevented?

Construction Shortcuts Contributed to the Boston Molasses Flood

In an article published in the Boston Globe, Mayville also discussed that in 1916, when the storage tank was designed and built, a great deal of pressure was on both the engineers and construction crews to complete the project quickly due to wartime production . The storage tank was needed to hold the molasses used in the manufacturing of munitions needed in European battlefields. In order to build the storage tank quickly, the construction team did not conduct critical tests that might have identified the weakness in the walls of the vessel. Additionally, records suggest that reports of leaks when the storage tank was first filled was ignored.

The Impact of the Boston Molasses Flood on Engineering Practices Today

Due to the extensive property damage and loss of life that occurred as the result of the storage tank failure, Boston officials took action after the accident to review and modernize the building standards and zoning in industrial areas. Another key take away from Mayville’s research, as well as the historical record, is the importance of testing materials and design theories as part of a proactive risk management strategy. Even without the benefit of today’s knowledge and technology, had the design and construction team used the best practices of the time and tested the vessel before its use, chances are the Boston Molasses Flood would not have occurred.