- Posted October 21, 2010 by
This iReport is part of an assignment:
Watch the mine rescue with us
CHILEAN RESCUERS DODGE THE BULLET 3 TIMES
Chile mine rescue. A teaching moment.
This may sting a bit. The ordeal and rescue of the Chilean miners was a genuine heart stopping moment in our history. No one could have felt differently watching these miners emerge from the womb of the earth. However taking an objective look at the proceedings as they unfolded live, allowed one to see that not only were the Chilean miners excruciatingly lucky but, in an instant, the result could have been completely different. One has only to look back at the United States NASA Challenger incident in the space program, where a single $10 O-ring malfunction precipitated this major national catastrophe in a much-vaunted event. The connection between NASA and the Chilean rescue is parallel, except with one major difference, the potential O-Ring moments in Chile did not occur. In Chile they were three potential O-Ring moments.
The first O-Ring moment was that unprotected, open 28 inch pipe at the surface through which at any time, a tool held by one of the rescuers could have fallen into that open surface pipe getting stuck in the lifting system and creating a major problem. Anyone who's been in the oilfield while drilling knows that the wellhead has to be covered and protected at all times. Forged, heat treated tools are very difficult to drill out when they get stuck in the pipe. Many a well had to be abandoned because a slovenly rig floor worker dropped a 20-inch steel wrench into the well bore. On the other extreme, it was difficult to watch all the orange clad rescuers milling around the unprotected wellhead knowing that a human body can fall into that open pipe. Drilling workers stumble and fall on the rig floor everyday. Easily visible in the video were the feet of the rescuers nonchalantly standing on the edge of that surface pipe during the 30 minute round trip of the capsule. A cheap clamshell cap with a center cable pulley would have done the job.
The second and most disastrous O-Ring event was visible when the capsule was pulled back to the surface and it was hanging from the cable in the well bore at the surface. There were no safety devices that were stuck between the capsule wall and well bore casing to hold the capsule from falling back into that 2200-foot hole if and when the brake on the cable assembly slipped. We know that hand brakes and parking brakes sometimes fail, it happens every day in automobiles and also on drilling rigs. On a drill rig they use metal slips which grab the pipe material at the surface so there's no way in the world it can fall back down that deep hole. Imagine what would happen if this 924 lb. Phoenix capsule got loose from its brake, with the cable unwinding wildly, on worldwide TV, in front of two Billion eyes and fell 2200 feet down the hole with one of the miners still inside the capsule. The worldwide uproar, the shame, the embarrassment and ridicule would have been phenomenal. Chile would never have lived it down. All that was required to prevent this O-Ring type event would be three pieces of wood, yes wood, cut in a triangular shape and slipped into the sides between the capsule and the surface pipe. In the oil field we actually call these lifesaving safety pieces: "slips".
The last, but least deadly O-Ring event was visible in the downhole chamber. When the capsule arrived at the bottom of the well shaft into the rescue chamber, it was obvious that it was not vertical. It was at an angle to the wall. There should've been a simple metal cradle leaning against the wall to keep the capsule at the same angle as the well shaft. It was obvious from the very first rescue attempt that the capsule was momentarily stuck as the crane began to pull it out of the hole. There was a visible stoppage of the upward motion on to the crane at the surface until the cable pull was able to jar the capsule loose. This could have been an event in which the cable from the crane would actually pull off the top of the flimsy capsule completely. A simple cradle leaning against the wall would have allowed the capsule to have entered and left easily at the correct angle, and without added stress on the capsule or cable.
Viva Chile, it was a great job and there were 33 extraordinarily brave men and lady luck to guarantee their safety. It was a teaching moment.
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Dr. Henry Crichlow, Professional Engineer, Norman, OK.
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