Mobile Crane Standard Addresses Overloads
The latest revision of the American national standard for mobile cranes, ASME B30.5-2014, brings major changes to the rules governing how crane users are to work within a lifting machine's capacity range, or load chart, and offers new guidance for inspection, maintenance and testing procedures.
Mobile cranes today are designed to a finer edge than in 1968, when the American Society of Mechanical Engineers published the first B30.5 standard. Cranes now use lighter, stronger materials and have more lifting power. These engineered systems include parts built to varying design factors. Overloading a component could compromise the system.
The latest B30.5 revision, which updates a 2011 volume, takes a more systematic approach to helping users avoid overloads. It ends the longtime tradition of load testing a crane to 110% of its rated capacity and prohibits going beyond the stated load capacity without express permission from the manufacturer. The standard also no longer requires manufacturers' load charts to distinguish between the point at which the crane could lose stability from the point at which the boom could buckle. This change addresses the temptation to overload the crane to the point that it begins to tip.
"The load chart is the load chart," said J. Chris Ryan, vice president of equipment for Boh Bros. Construction Co. during a B30.5 webinar that ASME hosted on March 25. "Don't exceed it," added Ron Kohner, owner of Landmark Engineering Services. Both are part of the expert panel that wrote the new B30.5 standard.
Overloaded components may not be obvious during an inspection, they noted, and as more cranes today are rented than owned, extra care needs to be taken to keep them in a safe state as they exchange hands. However, it still is possible for a crane to flex during a lift, causing an outrigger or crawler to come off the ground. The new standard now requires manufacturers to explain when this phenomenon is permissible and recommend action. "This takes the standard into an area that has never been addressed before," Kohner said. Also, an indicator that displays the horizontal position of outriggers in relation to the load chart must now be provided in the cab.
Daily inspections are now required to include structural members. They can be performed from the ground unless damage is suspected. Damage must be examined by a qualified person. "We want to make sure that if you see any anomalies in the crane, structure, boom or hook, you take the appropriate action," Ryan said. Further, repairs must return the crane to its original specifications unless the manufacturer or qualified person permits otherwise.
