Important Factors Reduce a Crane’s Lifting Capacity Below Load Chart Values
Lifts are often referred to as ‘critical’ simply because “it’s the biggest lift we’ve ever done,” but that shouldn’t be the determining factor, according to SC&RA’s new “Guide to Mobile Crane Safety Management.” There are certain aspects of some lifts that necessitate the classification of Critical because they present exceptional risk.
Only a small percentage of the lifts on most projects would be expected to fall into a ‘critical lift’ category. If a large portion of the lifting work legitimately results in this classification, the overall project risk exposure is undesirably high.
There are several criteria within most lift classification systems that could cause a large segment of lifts to be categorized as critical. As an example, if cranes are continuously found to be working at over 90% of their capacity, it might be time to reduce risk by simply deploying larger cranes. This is not to say that cranes cannot perform at 90% of their capacity. They clearly can.
Cranes in sound condition are fully capable of lifting 100% of the values shown within their published load rating charts and depicted on the operator’s in-cab electronic display. But it is still important to recognize and understand which lifting variables can reduce the crane’s lifting capability below the load rating chart values. Important examples of these factors are poor crane condition; exceptionally eccentric reeving of the boom tip; improper use of outriggers; poor/soft supporting soil; crane not level within manufacturer’s specifications; side loading of the boom; excessive swing speed; rapid acceleration/deceleration of the load; impact loading; high wind speeds; and exceptionally cold weather.
Published to fortify SC&RA’s ongoing efforts to reduce crane and lifting accidents, the 104-page “Guide to Mobile Crane Safety Management” reflects substantial changes in tools, technologies, and perspectives over the last two decades. Among developments covered are those resulting from new OSHA rules and updated standards such as the ASME B30.5 – Mobile and Locomotive Cranes.
The guide was written by Ronald Kohner P.E. and Robert Hontz. Both have over 40 years professional experience and have written extensively on crane and lifting safety throughout their careers. The “Guide to Mobile Crane Safety Management” is available in English and Spanish to SC&RA members for $99. The nonmember price is $199. Visit SC&RA’s website to purchase the new guide and other products or services.