In a fabrication or assembly facility there can be a host of material handling that occurs during the general nature of work. The delivery of steel plate, beam, tubing and other raw materials or equipment is often performed in a variety in ways.
Typically a forklift or telehandler will move material from a storage yard or building into a fabrication bay. The material often needs to be sorted for initial fit-up and assembly. That's when the cranes get involved. In bays with open ends, it may be inviting to integrate the use of a small mobile crane to assist the overhead bay cranes for material sorting and assembly.
When a boom type crane is tasked to work in a shop bay, the opportunity for accidental contact with obstructions is ever present. An even greater risk is at hand, with an overhead crane and mobile crane attempting to work in the same area. The overhead crane operator may not see the mobile crane boom due to fabrication obstructions. The mobile crane operator and assigned rigger/welder may not be looking up to ensure continued clearance with an approaching overhead crane. In both cases, the machines may be moving towards one another simultaneously with almost potentially disastrous results.
If one crane strikes another in this situation, the suspended load(s) can be easily dislodged and dropped, the load(s) can swing violently or there may be a crane derailment or tip-over. Nothing good can come out of this ticking time bomb.
If a mobile crane or other high reach machinery (aerial work platform, telehandler with mounted boom, high-mast forklifts, etc.) is working in a crane bay, the site management needs to ensure certain precautions are in place. The following are options that management can take to minimize the risk involving "dueling" cranes:
There are some in our industry who would strictly prohibit the use of high reaching machines in overhead crane bays, but that doesn't seem very practical. The secret is to have a game plan in place that minimizes the risk and have employees follow the approved procedures while adhering to the imposed operational restrictions. The ideas proposed here don't represent an exhaustive list. There may be a number of other approaches that can be taken to avoid an incident related to high reaching equipment in an assembly bay. The best approach generally includes a combination of mechanical or electrical restrictors, visible barricades and trained personnel who are actively respecting the existing operational conditions.
Mike Parnell, CEO of Industrial Training International, has over 33 years of experience in the Crane & Rigging Industry. His background includes the design and implementation of crane and rigging operations and training activities, rigging design, OSHA-based inspection programs, accident investigation, development of custom load-moving techniques and training tools, and the development of customized test services. He currently serves as a board member of the Association of Crane & Rigging Professionals, Vice Chair of ASME B30 Main Committee, and Chair of ASME P30 Lift Planning Committee.
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