On 29 July at 6:20pm as a Case 110HP Steam Traction Engine was being moved into its place in the fairground it violently exploded probably due to a critical low water condition. While we will probably never know the exact circumstances, investigation to date shows that the fusible plug failed to melt as it should have. Water sprayed onto the white hot crown sheet and exploded into steam at a rate that the boiler and safety systems simply could not cope with. The resulting explosion blew out the fire box and threw the engine 5 meters (15 feet) into the air. The flash of super heated steam and shrapnel ripped through the surrounding area killing the owner of the engine Clifford Kovacic, his son Billy Kovacic, and family friends Alan Kimble and Dennis Jungbluth.
The following is a quote The Plain Dealer a Cleveland newspaper.
Most of the injured were browsing a historical exhibit of agricultural machines as Clifford Kovacic, 48, of Spencer, prepared to back his gargantuan steel-wheeled, coal-fired tractor into a shady spot.
His son Billy, 27, who lived with his father, stood in front, guiding him.
The explosion spewed scalding water and searing metal fragments more than 300 feet in most every direction, and flung Billy into a truck cab more than 30 feet away, killing him instantly.
The 1918 Case tractor was torn in two.
Both Kovacics, Alan Kimble, 46, of Litchfield Township, and Dennis Jungbluth, 58, of Litchfield Township, suffered burns and broken bones, and all died from blows to the head, said Medina County Coroner Neil Grabenstetter.
Shrapnel pierced exhibit barns, punctured a 20-foot inflatable soda can and melted into the dashboard of a car parked a football-field away near the northwest entrance of the fairgrounds.
Fortunately this incident happened before the fair opened, had it happened during the week the magnitude of the disaster would have been much worse.
It appears at this time that the cause of the accident was three fold, poor maintenance, a failure to inspect, and operator error. The fusible plug should have been inspected prior to operation under pressure. A fusible plug is designed to melt when the crown sheet is uncovered allowing steam and water to escape from the boiler in a controlled manner into the firebox putting out the fire. A fusible plug can fail because it becomes covered in scale or other deposits insulating it and preventing it from getting hot enough to melt in time. A boiler should be regularly cleaned out and inspected. A fusible plug can also fail due to crystalisation of the metal due to repeated heating and cooling. After reviewing the article John Byers suggested that it is appropriate to periodically replace the fusible plug.
The primary device for detecting water level is the guage glass which reflects the level within the boiler. When the fire is hot, the water level in the glass is not constant it moves up and down a little as the water boils. As a backup to the glass, there are tri cocks (valves). Regularly during operation, and especially if the level seems constant, the tri cocks should be tested. These cocks are above and below the guage. When opened, water and steam should exit through the cock, if it does not then this indicates a blockage and the fire should be damped immediately and the engine allowed to cool as the water level is unknown. Water should not be injected until after the boiler cools.
The state of Ohio abandoned its inspection regime only last year. Australia, England, and most states of the United States have strict and strong inspection/testing regimes. While the operator error part of this accident could have happened anywhere, our local inspection policies should offer some protection.
There has been some conjecture that two police officers (both badly injured) were distracting the operator during this critical moment. Apparently the officers followed the engine into the fairground with the intention of citing the driver for damaging asphalt roads. If this is true, it does not detract from the operator error, the water level in an idling steam engine does not change quickly and the operator should have detected the low water level and dealt with it much earlier. However, law enforcement personnel do need to be aware that they cannot take a "step away from the vehicle" attitude with operators of old equipment.
One witness suggested to reporters that the operator did something with a control immediately before the explosion. It is possible that he noticed the low water condition and attempted to inject water into the boiler to bring it up. Instead he should have banked the fire (or dumped it if his engine supported that operation) and blown down the steam pressure then waited for the engine to cool. It may have been too late to do anything and it is possible that the operator was trying to do the right thing, we'll never know.
What is the lesson for us here? All of our equipment, steam or otherwise, was designed and built in a time when safety did not have the level of appreciation it does today. It was common for boilers to explode, fly-wheels to shatter and other disasters to occur. Today we expect our machines to shut themselves down when operated outside normal paramters. Todays human has been conditioned to believe everything they are told and to expect that society will protect them. This includes a faith in machines to the point where someone will not think twice about standing next to some huge behemoth while it operates. Unfortunately this translates into our world of dangerous antique equipment. While we the operators of our machines probably understand the dangers involved and take appropriate precautions to protect both ourselves and those watching us, the public do not understand the danger they may be facing and will often endanger themselves by standing next to a flywheel with loose clothing or while holding bags.
What should we do about this? Firstly, lets look in our own backyard and ensure we always operate with the maximum degree of safety to ourselves and those around us by inspecting our equipment whether required to or not and operating it carefully. Secondly we must embark on an education campaign, not in the useless Californian style of danger signs but with empassioned words. When someone asks you about your machine let them know how it works, explain to them what the controls do, explain to them how to be safe near the machine. Above all if you see another operator or a member of the public acting unsafely, do not hesitate in letting them know. It is your protection and theirs. If you fail to get satisfaction, take the matter to the organisers immediately. If you are unsure about how to operate your equipment, then don't operate it until you've been trained or have worked it out yourself.
What should the Ohio government do about this incident? They need do very little in the way of laws, perhaps they could make a free or at cost inspection service available to hobbiests. Several members of the ATIS Steam Engine list have commented that Ohio has become the dumping ground for unsafe machinary which cannot be sold in other states. The insurance companies are likely to regulate in these circumstances. Fairs and shows usually have indemnity insurance which protects the organisers and participants from liability when something goes wrong and offers some form of help and protection to those who are wronged. To minimise their risk, insurance companies will probably either wrongly ban the operation of steam or specify strong inspection and safety requirements. We've seen this trend in Australia at our shows, and I've seen this commented on (usually negatively) in English and American publications.
Lets all learn something from the Medina incident and ensure that we remember those who were killed and hurt by making sure this never happens again. Remember always that we hold the health and safety of others in our hands.
Please note that the conclusions drawn in this article, while likely, are not 100% sure. A formal investigation is under way and I will update this article as necessary as more findings become available.
[Sunday Aug 05] Thanks to Ted Brookover for pointing out my mistake in using the term "dry cocks" instead of "try cocks". I've always called them dry cocks, but on checking literature they are referred to as either "tri cocks" or "try cocks". Ted pointed out that there are three cocks, high, middle, and low which lends credence towards "tri" rather than "try".
Thanks to those people who have commented via e-mail on this article. I've made some changes based on suggestions from more experienced steam people than I. I've also had some comments on the prematurity of the article considering there is a formal invetigation in progress. The primary goal of this article is to increase safety awareness in operators, owners, and spectators rather than to find fault or lay blame for the accident. As stated above I will update the article as findings become known. For information on one particular respondant who accused me of writing a biased article from half a world away based only on newspaper articles. I'm actually in the USA at the moment and have discussed the incident with several experienced steam people from the area and around the USA.
Joe Prindle asked me to point out that a new boiler is just as likely to explode in similar circumstances and that we should be vigilant with new equipment too.
[Monday 6 Aug] Tragically another man has died from injuries sustainedin the accident, Bryan Hammond.
The Minnesota Department of Labour and Industry has published an article written by John Peyton director of the Certified Boiler Engineers for the Commonwealth of Pennsylvania. This article can be found at www.doli.state.mn.us/boilerohio.html. The article is reasonable for most part and includes photos of many of the damaged areas of the boiler. As yet, there is no official Ohio findings published. I'm in touch with their boiler inspector and hope to receive details from him when they become public. At this time, I'm not going to update this article from the information supplied by Mr Peyton until the official findings are released.