Bridge Crane Capacity Ratings

By Richard Wehrmeister

How significant are capacity ratings on bridge cranes? The capacity rating is part of every inspector’s checklist, but are we taking these for granted?

The Standards and Regulations state that bridge girders must have a capacity sign on each side of the bridge girder and in the case of dual trolley hoists each load block must include the capacity of each trolley/hoist.

Sounds simple, however it wasn’t long ago we were asked to provide pricing on proof testing a number of cranes. The customer provided us with a listing of cranes. One of the listed cranes had a capacity of 40 tons. Having visited the customer’s site a few years back we couldn’t remember a 40 ton bridge crane being at this site. We decided to revisit the site. What the customer described as a 40 ton crane was actual labeled 20/20 ton which had two 20 ton top riding trolley/hoists. Each load block was labeled 20 ton. We questioned the customer about the 40 ton rating. It didn’t look like a 40 ton crane. The
customer was very adamant about the capacity and said this unit has always been proof tested at 40 ton by others.

We still had doubts and upon leaving we recorded the manufacturer’s serial number. You guessed it, the manufacturer confirmed our suspicions. The bridge
capacity rating turned out to be 20 tons. We asked why they would label the bridge 20/20 ton. According to the manufacturer the customer wanted the capability of lifting a single pick on one hoist of 20 ton or spread a large load out of 20 ton between both hoists. Of course we asked the manufacturer why they didn’t just label the bridge girders at 20 ton. They claim “this is the way they have always done it and it is accepted practice”. When we
told them that this crane had been proof tested in the past at better than 200% of rating, their answer was “when the crane was purchased everyone was aware of the correct capacity”. That was 30 years ago.

Another problem in the industry is the fact that when a manufacturer designs a crane with two trolley hoists the design may take into account the wheel loads of eight wheels. When they do this the capacity load on the girder is spread out, this allows the manufacturer to design the crane using lighter girders. The problem with this is if the girder uses dual or single capacity signs, doesn’t mean that the girder will handle the capacity load from a four
wheel trolley.

The biggest fear we have is a customer removing twin trolley hoists and adding one trolley hoist at a total capacity of the two removed. We all know that years ago steel pricing was a lower percentage of over all cost in the manufacturing process. However steel prices today have become a very significant cost. Overhead cranes designed today seem to have become much lighter in regards to steel used.

In summary owners/users of overhead cranes must maintain manuals that include design specifications on bridge girder loadings and be available for review when inspections and proof testing is performed. Hopefully someday this would be incorporated into the Standards and Regulations.

Richard is a friend and colleague at the Crane Certification Association of America and General Manager of Advanced Overhead Crane.

Load Testing Reinstalled Equipment in the State of California

Posted with the kind permission of Calvin LeClair Konecranes, CA.

Recently, I had a customer who wanted to have load testing done on his monorails. His monorails were three ton capacity. Now, Load testing in the State of California is required on initial installations and every four years for equipment over three tons. However they often move the hoist to different locations and on different monorails throughout the facility. The question that arose was if we had to load test them every time a hoist gets re-installed on a different monorail.

In a letter from 1994 written by CAL-OSHA they state that if the hoist is not an integral part of the machine, then the monorail does not have to be load tested or certified. Then they go ahead and define a monorail as “a crane whose hoisting mechanism is suspended from, and is an integral part of, one or more trolleys mounted on a single track.” So what the heck does integral mean anyway? OSHA commented to us that this is a confusing part for people trying to interpret what the regulations mean, and I can definitely see why. CAL-OSHA does not explain what they are referring to with the word, “integral”. Even under the definitions it is not listed. What he told us was that if it is not defined in Title 8 then it should be referenced from a dictionary. He went on and referenced Webster’s Dictionary and stated that the term integral as, essential to completeness, 2. Composed of integral parts, 3. Lacking nothing essential. So what I gather from this is that all hoists are integral to any monorail.

The following is an excerpt from the email sent to us from CALOSHA. , A hoisting unit is integral to all monorail cranes. Without a hoisting unit, a monorail crane is not complete and cannot perform its intended function. Section 5022 requires that a proof load test be performed on a monorail crane every four years. It is silent when it comes to reinstalling the hoisting equipment on the monorail crane. ASME B30.11 requires an operational test on reinstalled equipment. It also says that a load test should be performed on reinstalled equipment as determined by a qualified person. The problem is that our code in 4884 requires that such cranes be designed, installed, and constructed to the ASME requirements. Cranes need to be inspected, tested and maintained per Title 8. Since Title 8 is silent on the issue of reinstalled equipment, my opinion is that a load test should be performed based on your recommendation. What does the manufacturer recommend?

So, in the end it is up to the manufacturer’s or crane servicing company’s recommendation. Now he did state that he suggest a load test be performed every four years per Title 8 5022, and a load test on reinstalled equipment be performed as determined by a qualified person as per ASME B30.11. However I don’t really get it. They put all these regs in place and state all these regulations that are required to be followed on all equipment over three tons. Then when asked about it they pretty much say below three tons it should be done as well but it is up to the discretion of a qualified person. I thought that these regulations were in place to keep people from using their own discretion? If my customer comes to me with these questions, I would recommend quarterly inspections on all their equipment but only load testing above 3 ton capacities unless it is a class C or D crane then I would recommend every four years as well. Anything below three ton it really depends on the severity of use of the crane or hoist. If it is used a lot then it really needs to be treated as a piece of equipment that has a capacity over three tons. I’ll leave you with this, do you really think 6,000 lbs is going to hurt any worse than 8,000 lbs?

Calvin LeClaire has worked in the crane industry for over 10 years both in installation and manufacturing of crane systems. He is currently in New Business Development at Konecranes in California.

Post is provided for general information only, we assume no responsibility for the accuracy of any particular statement and accept no liability for any loss or damage, which may arise from reliance on the information contained within.

Lifeboat Davit Testing

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