The 1 Ton yellow crane support beam jammed up at Friday morning, June 25.
The 40m vertex crane has a folding I-beam support to reach targeted areas. The rotating I-beam is 8 ft long. The folding extension arm gives you another 4 ft.
The 12 ft full reach can be achieved by a straightening of the 4 ft piece. There is a spring loaded latch on the top of the I-beam that locks down when the two I-beams align.
This lock joins the two beams into one rigid support beam for the jib trolley to travel. The position of this latch is visible when standing below, albeit not very well.
To be safe it is essential that this latch is locked down fully before a load is put on the crane.
We were preparing to pump down the 40m vacuum system on Friday morning. The straight alignment of the 8 and 4 ft piece made us believe that
the support beams were locked. In reality, the latch was not locked down. The jib trolley was driven to the end of the 12 ft I-beam. The 200 lbs ITM-east door was lifted
when the 4 ft section folded 50 degrees around the pivot point. This load of door + jib-trolley + 4 ft I-beam made the support beam sag about 6 inches
The door was removed from the jib hoist with the blue Genie-lift. The sagging was reduced to ~3".
The Genie-lift platform was raised to support the sagging crane jib-trolley. The lab was closed off to ensure safety and experts were called in for consultation. It was decided to bring in professional riggers.
Halbert Brothers, Inc. rigging contractor came to the lab Tuesday morning to fix the crane. The job was to unload the I-beam with safety support below. They did a very good job.
The static deformation of I-beams sprung back to normal position. There are some deformation of the I-beam ~2 mm where the beams were jammed under load.
It is not clear if this is a new deformation or if the crane sections have always been mis-aligned by a couple of mm.
The crane was tested with 450 lbs load at 12 ft horizontal travel position. The folding of I-beams were repeatedly tested for safe operation. Its a 1 ton crane, but we tested it with 450 lbs because that's what we had on hand.
We're working on the safety upgrade of this lift to prevent similar accident from happening.
Atm 1) load testing 2007
Atm 2) jammed-sagging under ~400 lbs, horizontal
Atm.3) jammed-folded 50 degrees, vertical
Atm.4) static deformation of I-beams
Atm.5) unloading in progress with the help of two A-frames
Atm.6) it is unloaded
Atm.7-8) load testing
Atm.9) latch locked down for safe operation
Atm.9) zoom in of the crane sections misalignment