Thursday, October 28, 2010

December 9th, 2008

St Petersburg, Russia. A saddle jib tower crane that appears to be a Kroll suffered a structural failure that is interesting. I was wondering at first if it was an inner pendant failure. The only pictures that I can find are the ones I've screen captured from the video so they are poor resolution photos. You see how the jib is hanging down but not pointed straight down indicating that it still has support from above. You look at the top chord and you can see the single pendant still under tension. Give it's location in terms of distance from the tower, it's likely that it's a single pendant jib.

Moving back you see that the #1 jib section is twisted and has broken lacings. It really appears that the jib has structurally failed. While that in and of itself isn't something new, take note of the hook and rigging... it's empty. No side loading, no overloading, nothing is written about heavy winds but could it be in the video in Russian?

This accident reported no injuries. It was over, or adjacent to, a medical center that had to shut down as much as possible. Cranes seem to spread out enough of the load that they rarely take out entire buildings, save New York with Massive Favco's coming down on brick structures. But counter weights will punch though multiple floors. if not all of the way to the basement. That being, it's prudent to move as far away as possible.

This may be a clear example of why you should be looking at your crane and walking the jib periodically as the operator. There are good bellman that can do it, but the operator is responsible for a safe crane and I'm here to tell you, riding the trolley doesn't do it. You must see both sides of the jib. You have to look for deformations in the lacings. You have to look at the welds and expose the metal under new paint cracks. If you find them, put primer on them. The primer will crack very quickly if the metal is moving and the metal is likely to move long before it fully fails. That being, I'm pro riding the trolley to review the trolley lines, seeing the load line and knowing how the trolley is performing. The core point being that simply riding the trolley is a lame inspection, and that's putting it politely.

Side note: New FLV downloader, dealing with learning curve. Find full vid and text here. I couldn't find any other stories on accident.

аварии башенного крана, крах башенный кран

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