I pulled my car into the parking lot of the sprawling General Motors plant in Baltimore around 11:15 in the evening and found a choice spot up front near the time clocks. I punched my card, said hello to the guard at the gate, and started the long walk to the shop. I was working the midnight shift with a crew of 24 other mechanics. Unless there was some kind of a breakdown on the assembly line, a typical night’s schedule would have us hanging around the shop until 1:00 a.m. when the line shut down. Then we would go to work. The line would start again at 5:00 a.m., so we needed to finish by then.
General Motors made Chevy and GMC vans at this plant. Machines used on the assembly line were powered, for the most part, by either air or oil pressure. Smaller tools, such as drills and automatic wrenches, tended to be air-powered, while the larger machines used for welding and other heavy tasks were powered by hydraulic oil pressure. One or more large hydraulic pumps, stationed near the machine being powered, generated the oil pressure. Our crew was responsible for maintaining and repairing these hydraulic units and other pipes used to conduct fluids and gases in the plant.
A large hydraulic accumulator lay on the floor in the middle of the shop. The unit failed and was removed from the assembly line on the previous shift. The second shift crew had rebuilt it, and it was waiting to be installed back on the line. The machine it had been attached to limped along without it, slowing down the line a bit, and management was anxious to see it back in service. It looked like a five-foot-high oxygen tank but was painted brown instead of green. Inside the accumulator was a thick rubber bladder that ran the length of the tank. When hooked up to a pressured oil line, the accumulator acted like a battery, storing oil pressure that could be released when needed.
My coworker Rick Romano and I started looking it over and think about what tools we would need to install it. We had done these installations many times before, and it was simple to place it in the back of an electric cart and carry it over to the line. After that, we would hook up two hoses and open two valves. I suggested to Rick that we go ahead and install it at midnight when the production line took a 15-minute break. We both thought it was good to get this small job done so we would have more time to do the preventative maintenance assigned to us without rushing to finish by 5:00 a.m.
Rick agreed, and we loaded the accumulator on a small electric truck and hauled it over to the line. We hooked up the hoses and paused for a moment. “Should we go ahead and open up the valves now or wait until the line goes down?” I asked Rick. We bantered back and forth for a bit, and somehow, I let it rip. Placing my hand on the yellow rubber-coated handle of the inch-and-a-quarter valve, I pulled it slowly from its 90-degree "off" position towards the inline "on" position. The handle hadn’t moved more than a few degrees when Rick and I knew something had gone terribly wrong.
I shoved the valve handle back into the closed position but it was too late, the havoc that I had unleashed was unstoppable. Unknown to Rick and me, when the accumulator was rebuilt on the second shift, the bladder wasn’t tucked securely into the tank and was crimped and cut open when the cap was attached. This allowed the highly pressurized oil that was supposed to be contained in the tank into the low-pressure side of the system. The low-pressure side was designed to hold no more than a pound or so of pressure, and we charged it through the failed accumulator at thousands of pounds per square inch.
To our right side sat a row of four 250-gallon oil tanks that supplied oil to the four large hydraulic pumps that powered this portion of the line. Each of the four tanks had an end cap held in place by a single bolt and sealed with a thin rubber gasket. One by one, the gaskets blew out from under the end caps, and sticky red hydraulic oil sprayed from each unit. In less than a minute, one thousand gallons of oil spread out across the floor in every direction.
We called the maintenance dispatcher, and he, in turn, started notifying cleaning crews and production managers. In a few minutes, every senior manager working at the plant had rolled up in their electric scooters. It didn’t take long for them to decide that the body shop was going down. The rest of the plant would shut down 30 minutes later when they ran out of bodies.
When a large auto plant goes down, losses are calculated at a staggering rate. Normally, this plant lost $10,000 per minute when the line wasn’t running. What is the total bill for the outage I caused? One million, two hundred thousand dollars.
By the time I arrived the next evening, management had already discussed the matter with the crew on the second shift, who had rebuilt the accumulator. For a change, management was reasonable, and they said they realized we didn't have the proper training for rebuilding the unit and that they would bring a factory representative in to provide training for all shifts. No discipline was handed out to Rick, me, or anyone on the second shift. To date, this has been the most expensive mistake that I have ever made.
General Motors made Chevy and GMC vans at this plant. Machines used on the assembly line were powered, for the most part, by either air or oil pressure. Smaller tools, such as drills and automatic wrenches, tended to be air-powered, while the larger machines used for welding and other heavy tasks were powered by hydraulic oil pressure. One or more large hydraulic pumps, stationed near the machine being powered, generated the oil pressure. Our crew was responsible for maintaining and repairing these hydraulic units and other pipes used to conduct fluids and gases in the plant.
A large hydraulic accumulator lay on the floor in the middle of the shop. The unit failed and was removed from the assembly line on the previous shift. The second shift crew had rebuilt it, and it was waiting to be installed back on the line. The machine it had been attached to limped along without it, slowing down the line a bit, and management was anxious to see it back in service. It looked like a five-foot-high oxygen tank but was painted brown instead of green. Inside the accumulator was a thick rubber bladder that ran the length of the tank. When hooked up to a pressured oil line, the accumulator acted like a battery, storing oil pressure that could be released when needed.
My coworker Rick Romano and I started looking it over and think about what tools we would need to install it. We had done these installations many times before, and it was simple to place it in the back of an electric cart and carry it over to the line. After that, we would hook up two hoses and open two valves. I suggested to Rick that we go ahead and install it at midnight when the production line took a 15-minute break. We both thought it was good to get this small job done so we would have more time to do the preventative maintenance assigned to us without rushing to finish by 5:00 a.m.
Rick agreed, and we loaded the accumulator on a small electric truck and hauled it over to the line. We hooked up the hoses and paused for a moment. “Should we go ahead and open up the valves now or wait until the line goes down?” I asked Rick. We bantered back and forth for a bit, and somehow, I let it rip. Placing my hand on the yellow rubber-coated handle of the inch-and-a-quarter valve, I pulled it slowly from its 90-degree "off" position towards the inline "on" position. The handle hadn’t moved more than a few degrees when Rick and I knew something had gone terribly wrong.
I shoved the valve handle back into the closed position but it was too late, the havoc that I had unleashed was unstoppable. Unknown to Rick and me, when the accumulator was rebuilt on the second shift, the bladder wasn’t tucked securely into the tank and was crimped and cut open when the cap was attached. This allowed the highly pressurized oil that was supposed to be contained in the tank into the low-pressure side of the system. The low-pressure side was designed to hold no more than a pound or so of pressure, and we charged it through the failed accumulator at thousands of pounds per square inch.
To our right side sat a row of four 250-gallon oil tanks that supplied oil to the four large hydraulic pumps that powered this portion of the line. Each of the four tanks had an end cap held in place by a single bolt and sealed with a thin rubber gasket. One by one, the gaskets blew out from under the end caps, and sticky red hydraulic oil sprayed from each unit. In less than a minute, one thousand gallons of oil spread out across the floor in every direction.
We called the maintenance dispatcher, and he, in turn, started notifying cleaning crews and production managers. In a few minutes, every senior manager working at the plant had rolled up in their electric scooters. It didn’t take long for them to decide that the body shop was going down. The rest of the plant would shut down 30 minutes later when they ran out of bodies.
When a large auto plant goes down, losses are calculated at a staggering rate. Normally, this plant lost $10,000 per minute when the line wasn’t running. What is the total bill for the outage I caused? One million, two hundred thousand dollars.
By the time I arrived the next evening, management had already discussed the matter with the crew on the second shift, who had rebuilt the accumulator. For a change, management was reasonable, and they said they realized we didn't have the proper training for rebuilding the unit and that they would bring a factory representative in to provide training for all shifts. No discipline was handed out to Rick, me, or anyone on the second shift. To date, this has been the most expensive mistake that I have ever made.
