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Corrosion Blamed for Deadly Ohio Fair Incident

Tuesday, August 8, 2017

Comment from Mario Colica, (8/8/2017, 3:55 AM)

Looking at the picture, it seems that the only protection against rust was a common paint. No signs of Zn coating appears.If the steel was covered with a Zn coating(arc-spray) of 200-300 um the incident would be avoided

Comment from Simon Hope, (8/8/2017, 6:58 AM)

It is the internal of a box section that has been the area where the corrosion occurred, zinc metal spray on the outside would not have helped in this circumstance though it might possibly have reduced any thinning due to external corrosion creating a crack nucleation point. What was required was either fully sealed box sections or if not fully sealed, a full endoscopic inspection regime to determine any break down or corrosion. Sealed box sections should not get internal corrosion as the oxygen is depleted creating an inert atmosphere. These areas are best protected with inhibitive waxes as the practicality of blasting and coating is not really an option.

Comment from Harman Metzger, (8/8/2017, 7:29 AM)

Maybe a few portal / drainage holes and hot dip galvanizing during fabrication would provide a longer life for this type of structural support.

Comment from peter gibson, (8/8/2017, 10:33 AM)

Inspection... these inspectors don't check for corrosion. Look at frivolities like nuts,bolts and the like.Corrosion issues not on the horizon. These things are overused anyway. The inevitable happened.

Comment from Martin van Leeuwen, (8/8/2017, 11:03 AM)

Hot Dip Galvanizing of the structure would have protected the inside also against corrosion as the full surface gets covered by zinc when it is immersed in the zinc bath. Nevertheless, a very tragic accident.

Comment from Thomas Van Hooser, (8/8/2017, 12:24 PM)

It is clear that an inadequate inspection program was in place before the incident. Many lessons learned in this unfortunate and preventable event. Will be interesting to review root causes and management failures.

Comment from M. Halliwell, (8/8/2017, 12:46 PM)

Actually, Peter, corrosion is on the list, but they are looking for external corrosion. However, in many amusement park rides, like this one, internal corrosion inspections are not often part of the deal. It's like with far too many buildings...if the façade is good, then the internals are often missed, even if there is a design flaw (like not having a fully sealed square section in this case or the internal corrosion of a building dropping 1400 lbs of granite on a Philly street in another recent article). Preventable accident? Most certainly, yes. But hopefully, this tragedy leads to changes in inspection, design and manufacture to prevent a future recurrence.

Comment from David King, (8/8/2017, 5:52 PM)

Even if the component was galvanized on the inside and left on it own without a protective coating or other to look after the zinc, the cathodic protection can still diminish if subjected to corrosive elements. An example being a galvanized tubular boat trailer that gets immersed in salt water. all the washing of the exterior is not going to stop what goes on inside, and eventually the trailer will collapse, as regularly happens if not detected early. Am really surprised that such an intricate component with a critical loading, that being human life on the end, did not have an internal inspection procedure in its maintenance program.

Comment from Martin van Leeuwen, (8/9/2017, 3:50 AM)

David, regular immersion of hot dip galvanized (HDG) steel of a boat trailer in salt water will give a totally different zinc corrosion speed (due to the salinity) than occasional condensation of moist in air on the zinc surface (no presence of chlorides). Corrosion speed will be different and that is why different corrosion atmosphere classes exist in corrosion standards. Any coating has it´s service lifetime and will need maintenance in the end. Metallic zinc coatings are easy to apply at the inside, due to the nature of the HDG process, and do extend the time-to-maintenance significantly. Still, checking structural integrity of the steel parts shall be part of the inspection plan.

Comment from Mario Colica, (8/9/2017, 5:00 AM)

only a few remarks at the Simon Hope Zn thermal spray can be applied both internal and outside the steeel structure (not only inside) Morever the fact that you can reach a Zn coating of 500 microns and can add a seal on the top of Zn surface ; this grants a cycle life duration of the struccture for more than 50 years without or little maintenance. Furtermore , the HDGalvaning which is another valid protection against rust has a limit of the coating ( the Zn thickness is of 75-up to 12 microns) and this means less duration

Comment from Stephen Dobrosielski, (8/9/2017, 8:02 AM)

Good discussion about the corrosion (or should I say corrosion prevention) of the failed member and the inspection procedures on amusement rides. If the ride was 18 years old, I am certain that the internal coating (if there ever was one) had reached the end of it's service life years ago. To clean and recoat the internal surfaces of the box would require some disassembly. I feel that metal fatigue needs to be researched in this instance. The failure as displayed in this article says the parent material failed, but I read elsewhere that a welded connection was involved. Regardless, a corrosion pit could easily be the source of a fatigue crack that simply propagated (nearly instantaneously) resulting in loss of innocent life. Tragic, but the devil is always in the details.

Comment from M. Halliwell, (8/10/2017, 11:36 AM)

Stephen, you bring up another potential source of the corrosion...if it was a welded connection, there is also the possibility of dissimilar metals (even something as minor as different alloys) being welded together, which could result in galvanic conditions that could contribute to or accelerate corrosion. On top of that is metal stress and fatigue from cyclic loadings and the influence of those loadings on cracks. There are a lot of potential circumstances and "what ifs" to look into on this one. My condolences to the family who lost their loved one and my hopes that this incident will update the way these rides are manufactured and inspected so that we reduce the potential for a recurrence.