Yes... When Overloading a Crane is Required
The recent few Crane College articles have delved into issues surrounding Bridge Crane Capacity. More specifically we’ve reviewed the “Rated Capacity,” that is, the maximum legitimate lift. We’ve looked into the concept of engineering “safety factors,” and how crane end users SHALL NOT encroach into these safety factors.
Who’s the Boss Here?
As a quick aside, it’s important to understand who makes the rules that cover these situations. Unfortunately, industrial safety policies are covered by a multitude of specifications, CMAA, HMI, ANSI, and OSHA to just name a few. Through the concept of “incorporation by reference” there are literally hundreds of documents in the mix. The CMAA Spec 70 alone incorporates over two dozen references in just the opening pages of the spec. The CMAA incorporates things like AWS spec for welding, ASME spec for bolts and fasteners, and someone else for paints and coatings.
For the purposes of this topic, I have chosen to use two of the primary level specifications, ANSI (The American National Standards Institute) and the OSHA 1910 specs. These are US specs and I’m not sure the extent to which other countries adopt these policies.
Most recently, I wrote about the two circumstances in which purposely overloading a crane is acceptable.
1. Planned Engineered Lift
2. The initial crane system load test
PLANNED ENGINEERED LIFTS
The Planned Engineered Lift is both “Planned” and “Engineered.” It is a logical and systematic process by which engineers are called in to check all twelve of the links in the chain of the lift. Most cranes will never be exposed to this process, which means that Crane College paper of mine would be a good one to file away somewhere, on the “oft chance” that some day you just might need to execute a “Planned Engineered Lift.”
INITIAL SYSTEM LOAD TEST
Where the Planned Engineered Lift is a “someday/maybe” possibility, the Initial Crane System Load Test is a mandated, day one requirement.
OSHA 1910.179 Paragraph K2 states the following;
Rated load test.
Test loads shall not be more than 125% of the rated load unless otherwise recommended by the manufacturer. The test reports shall be placed on file where readily available to appointed personnel.
ANSI B30.11 requires the following;
11-2.2.2 Rated Load Test
(a) Prior to initial use, all new, extensively repaired, and altered equipment shall be tested and inspected by, or under the direction of, an appointed or authorized person, and a written report should be furnished by such person, confirming the load rating of the system. The load rating should no be more than 80% of the maximum load sustained during the test.
100 Ton Rated Capacity new crane
100/0.80= 125 Tons test weight required to perform load testing
IMPORTANT NOTE: This will require that the hoist overload protection system be temporarily bypassed for the duration of the test. I have personally performed these tests and even gone to the precaution of looping my car keys on the bypass jumper wire in the crane control panel, to make sure I couldn’t drive away without removing the bypass wire and therefore reinstating the overload protection system.
Warning Regarding ANSI Interpretation
Over the years, I have ran into a number of projects in which the buyer would question my including a line item price for the load testing. The buyer would say that my competitor didn’t include load testing because they said that all hoists had to be load tested at the manufacturers factory.
The first time I heard this objection, I thought we might might be wrong. I went back our office and combed ANSI, ASME, CMAA and HMI. After carefully parsing the words I zeroed in on the phrase “confirming the load rating of the **system**.” In other words, you have to check the viability of not just the hoist, but also the entire structure holding the load. This chain of interconnected structures includes;
- Hoist trolley
- Bridge girder
- Bridge girder connection
- End trucks
- Crane rails
- Crane support beams
- Crane support columns and/or building columns
- Support column footings
The only way to “confirm the load rating of the system” is to load test the installed and completed crane "in place" thereby also load testing the runways, columns and support structure too.
Separating the Men from the Boys
As a good test of crane knowledge, I would suggest buyers ask what procedure their prospective bidders have regarding the Load Testing of their crane. They should be able to answer, a) is load testing required, b) size of the load and c) how they plan to obtain the test weights. If they can’t answer all three, then and there (without going back to the office or making a call) strike them off the bidders list.
Explicitly Include Load Testing in Your Bid Specs
Lastly, explicitly include the requirement of an ANSI/OSHA load test in your bid specs. It’s always easier to explicitly include it in the specs rather than argue about it later.