A wind turbine was being erected as part of a small wind energy park. The wind turbine tower and the nacelle housing the generator were successfully installed. The three-bladed rotor assembly was installed and connected to the nacelle as the last major component of the wind turbine. (more…)
Recently, we had the opportunity to observe a semi-annual inspection of a commercial cooking fire suppression system. Before we get too far into this we would like to point out that we talked with one of the company’s owners as well as the technician about our presence there and the questions we would ask the technician. Neither of them had a problem with this request. (more…)
A production building was being constructed at a cement plant. A large crawler crane was being used to install the pre-assembled metal wall framing of the building. The weights and lift radii of the four wall framing sections, along with the rigging spreader and other lift equipment, were within the rated capacity of the crane. (more…)
One of the most common features of machinery, consumer products, and assemblies of any type is the bolted joint. Sometimes the joint fails, with results ranging from inconsequential to catastrophic. The design of a joint is in the purview of an engineer, who must consider the material to be joined, the geometry of the joint, the loads imposed on the joint, the strength of the connectors (i.e., bolts, screws) environmental effects (i.e., temperatures, corrosion) and perhaps other factors. (more…)
A forklift fell off the loading dock of a warehouse as it was in the process of entering a semi-trailer that was being loaded. The forklift fell because the semi-trailer and the connected truck rolled away from the edge of the loading dock as the forklift passed over the dock leveler into the trailer. The repeated braking forces of the forklift as it carried loads onto the trailer caused the trailer to move away from the loading dock. The semi-trailer wheels were not chocked to prevent movement away from the loading dock. (more…)
The boom of a hydraulic crane was bent while removing temporary sheet piles at a construction site. A vibratory hammer had been placed at the top of the sheet piles to both drive and remove the piles. The vibratory pile driving placed no significant loads on the crane boom, as that operation relied on the weight of the sheet piles and the vibration of the hammer to sink the piles into the soil. The vibration of the hammer and the lifting force of the crane boom were needed to remove the sheet piles from the soil. (more…)
The ongoing frigid temperatures serve as a reminder of the many investigations by Warren engineers involving fire sprinkler systems that have failed when some part of the system was exposed to the sub-freezing conditions. Interestingly, failures do not necessarily occur within the area of greatest freeze exposure, as the failure mechanism is the extreme pressure that results from the growth of an ice plug inside the exposed pipe in which the high pressure will rupture the weakest component which may even be located in a heated area of the sprinkler system. (more…)
During winter ice storms, power to residences is often lost and homeowners revert to using gasoline powered portable electric generators. It is often thought by some homeowners that leaving a generator outside in the severe weather may damage it or affect its performance and therefore resort to bringing the unit inside the shelter, typically, the garage. This is particularly hazardous when the generator is run for an extended period of time as carbon monoxide (CO) poisoning from the toxic exhaust gas can cause death. In addition, other hazards including electric shock, electrocution, fire and burns potentially can occur. (more…)
Mobile cranes depend on stability through their outriggers. These are the four “legs” that are deployed onto soil or other working surfaces adjacent to the crane. When a mobile crane is set up at a site, the outriggers are deployed by a hydraulic mechanism that extends the four outriggers beyond the crane body and then jack the crane free of its wheels so that it is supported by the outriggers only. (more…)
The phenomena of wood igniting when exposed for extended periods of time to temperatures below wood’s published ignition temperature value has been of considerable interest in recent years. (more…)
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