Medina Fusible Plug Raises Questions

The Medina Report and the Case 110's fusible plugs: What the report doesn't answer raises more questions


| May/June 2002



J.I. Case 32/110 HP Pre-Canadian Boiler

J.I. Case 32/110 HP Pre-Canadian Boiler: This drawing is a composite of various pieces of information provided by the Medina County Sheriff's Department.

In the March/April 2002 issue of the Iron-Men Album I wrote two articles on fusible plugs examining both the history of fusible plugs and the condition of fusible plugs in my own equipment. The first article was an attempt to garner an historical perspective of the importance placed on fusible plugs, while the second article focused on the capacity of the fusible plugs in my own equipment to perform as intended. Both articles were motivated by my need to understand conflicting statements I read about the tragic explosion of the Case 110 on July 29, 2001 at the Medina County Fairgrounds.

In this article I have used results from the investigations I documented in the two previous articles to raise some questions related to understanding the disaster in Medina. To this end, I have focused primarily on three findings from the Medina County Sheriff's report. I have tried to confine comments to verifiable facts, and I have also tried to note those places where I am aware of having digressed into speculation.

Findings

The Medina County Sheriff's report states that the water level in the boiler of the Case 110 was low. In its summary of the causes of the explosion and the failure of the Case's crown sheet, the report states on page 18, Section 1, that, "This failure most likely occurred due to a lack of sufficient water in this area to insulate the already structurally weakened stay bolts and sheet and over firing." The report goes on to say that, "Apparent over firing and failure to maintain an adequate, constant water level" was a critical factor in the explosion.

As for the fusible plug, the Medina County Sheriff's report clearly states the fusible plug did not melt. In Section 2 of the report, an Aug. 10, 2001 letter from Dean Jagger, chief boiler inspector for the state of Ohio, to Lt. John Detchon of the Medina County Sheriff's Office states simply: "Fusible plug was still intact; the center had not melted out."

Additionally, John F. Wallace of the department of Materials Science and Engineering at Case Western Reserve University led an investigation team that examined the fusible plug from the Case 110. An Aug. 3, 2001 letter from Wallace to Lt. Detchon states: "The examination of the contents of the fusible center of the tractor plug and the melting temperature of the central contents of the small plug section showed that it was produced from 100 percent tin. The center section of the new plug obtained by Bill Kennedy was also 100 percent tin. Both of these materials have a melting temperature of just under 450 degrees F, or 232 degrees C; The fact that the material was the same and did not melt indicates that these plugs were not the direct cause of the failure." The Sheriff's report concludes that the metallurgical laboratory found the soft plug to be good.

Understanding the Facts

One of my difficulties is that I cannot understand how all three of these statements can be true.