What to consider when installing overhead cranes on existing runways, by Tad Dunville, director of corporate development at Ace World Companies.
When one talks about cranes, many people think of the tower cranes they see on city skylines. Even someone completely detached from this industry might be able to sketch a mast and a jib, while the particularly astute would add counterweight, cab and even a hook. I doubt they’d include a climbing frame and trolley, but that’s understandable. They could probably also give a basic engineering theory as to how it works and why it doesn’t fall over.
A smaller percentage of the population would be able to draw an equally good illustration of an electric overhead traveling (EOT) crane. This is primarily because the majority are hidden in factories and manufacturing facilities. However, if you borrowed their sketch pad and drew one for them lifting, say, a steel coil, they would no doubt apply the same layman’s theory as to how it moves along the runway, which supports it and stops it falling out of thin air. It’s simple, right?
It’s puzzling—no, incomprehensible—therefore that even in large manufacturing facilities where busy production lines move heavy product around on an hourly basis, sometimes in high duty cycles, often little regard is given to crane runways. In construction of runways, there is much ambiguity with different standards governing buildings and cranes, which is certainly contributory to why many shy away from the subject.
A runway is typically installed by the company putting up a building. Hopefully, by that stage, consultation has already taken place and it has been engineered to withstand the stresses placed upon it by an EOT crane. In a thorough design process, all parties will know in advance the purpose of the building, nature of the work, type of crane required and install a suitable, safe runway. There are different types of runways but that would be redundant detail in this blog.
Of course, such thoroughness isn’t always evident and problems can ensue. Who fixes those problems? Who acknowledges fault—builders, architects, installers, crane companies, end users? Well, that depends. And, as I said, standards don’t really help. Whatever the outcome, it’s nearly always expensive and frequently involves lawyers, particularly if an accident occurs.
All this is even when new cranes are fitted to shiny new runways. Imagine the problems therefore when it comes to existing, sometimes very old, runways. And that’s what this blog is about.
Here’s the key message: get a runway survey. If you’ve got an existing runway and you’re investing a significant amount of money on a new crane, don’t cut a corner and assume the runway is in good condition. There is a modern way of surveying a runway that essentially involves shooting multiple lasers around the structure and producing a digital report. The other, more traditional inspection, involves someone accessing the runway and performing a manual inspection. I recommend getting both.
Why? Because it might be a case of spending $10k to avoid costs in excess of $100k. It might mean a new crane will work at capacity for a decade instead of breaking down on the second shift because the new wheels don’t run smoothly on an old runway that it turns out had a defect all along. A proper inspection could prevent downtime or worse and mean a lawyer never has to find his way to your office. As I alluded to above, imagine how complicated it gets when it comes to establishing who is at fault.
Consider the likelihood that a new crane and an old runway aren’t going to get along famously. A lot would have changed in, say, 20 years since the runway was installed. A concrete building could have settled; the crane application might have changed; constant abuse could have knocked a rail out of alignment or a crane out of square; and / or the old crane might have increased its workload as a company grew or changed the markets it served. The possibilities are endless and all of them make for good reasons to get the runway surveyed.
Fit for purpose
Once the runway has been surveyed, passed, repaired or reinstalled, further consideration should be given to the crane. For the same reasons as above, updating the crane with a like for like solution might be just as damaging as not getting the runway inspected. Where the runway is typically the department of the builders and architects, this is the part where one needs to choose their crane supplier carefully and seek expert advice. If a 5 ton unit was used as a standby crane to lift the odd load of 2 tons, but demand is such that the crane needs to lift 4.5 ton loads for hours a day, there will be a better solution than an updated version of the 5 ton crane.
A good crane company will get extensive information from the end user about the application, how it’s changed, how it’s likely to evolve and their plans for the future. It’s actually rare that a duplicate crane is the best solution years after the initial installation. It might be the case that a more expensive initial purchase will save on maintenance, downtime and subsequent upgrades further down the road. It’s the same theory as getting the runway surveyed.
Heed the warning
In closing, I’ll share a couple of anecdotes with you, both of which involve the installation of a new crane on an existing runway.
The first is about a time when a company I worked for came to installing a crane and the runway looked visibly out of line. We told the user that we couldn’t install the crane until the runway was straightened. The building was built to spec and was one of four identical units. The developer had marketed them as being suited for overhead cranes and welded them to make it look like that was so. This was never the case. The tenant had to pursue the developer who claimed the runway was good. To cut a long story short, the tenant had to pay $100k to clean up the runway, by which time he had lost four weeks and the knock on effects almost put them out of business.
The second involves a 500-foot runway. It appeared to be in good order but the EOT crane kept wearing out its wheels. They were covered by warranty but the crane manufacturer knew it wasn’t down to standard wear and tear and, moreover, the constant repairs were having a financial impact on their business. Imagine the time the engineer had to take to travel to the facility and complete repairs etc., aside from the cost of replacement wheels. After further investigation the crane company was proved right—the runway was defective and it was causing the wheels to wear. This time a lawsuit followed and, again, the resulting costs were crippling, chiefly related to the delay in starting what in this case was an auto engine plant. The cost to redo the runway was actually minuscule by comparison.
Have you ever seen a digital stress analysis on a crane or other moving structure? In simple terms, a computer-aided design (CAD) drawing of, say, an EOT crane is color-coded where the forces are greatest as a crane travels and lifts. It’s eye-opening to witness the pressures that crane parts and runways have to withstand and, thus, no surprise when problems are encountered when due attention isn’t paid to the runway or selection of the crane.
Thank you for reading. Follow us on Twitter at @AceWorldCompany
Director of Corporate Development, Ace World Companies
Posted on 9/23/2016 at 3:00:00 AM