Investigation of the December 30, 2014
incident at Ford Kansas City Assembly Plant,
U.S. Department of Labor
Occupational Safety and Health Administration
Directorate of Construction
Report Prepared by
Mohammad Ayub, P.E., S.E.
Office of Engineering Services
Directorate of Construction
A fatal incident occurred on December 30, 2014 at approximately 8:30 a.m. at the Ford Kansas City Assembly Plant (KCAP) in Claycomo, MO. The incident happened when the welds on a bracket holding a safety pin supporting the weight of a carriage suddenly failed, causing the carriage to slip off the pin and fall, pinning an employee who was working below the carriage.
KCAP produces trucks and other vehicles, and carriages are an essential part of the assembly line. To accommodate the next generation of F-150 trucks (Code P 552) which are wider than the previous models, the carriages had to be adjusted for a wider platform. This involved relocating the four safety pins holding the carriage at four corners. KCAP retained KCI, Inc., of Kansas City, MO to perform design and construction for the relocation of the pins. The new location of the safety pins required that new holes be created in the existing ¾” plates of the counterweight steel columns, and that a plate bracket be field welded to the columns. It was the weld on such a bracket that failed causing the incident.
The KCAP was closed for the 2014 Christmas recess which provided an opportune time to make the changes to the carriage before assembly would begin for the new year. The work began on December 23, 2014 with day and night shift crews. For the next four days, December 23-27, a number of activities were performed, e.g., removing existing decking components, existing column guide bars, de-skid fences, installing new decking components, etc. By the night shift on December 27, they were ready to cut/burn the holes in the plates attached to the steel column flanges to relocate the safety pins. First the hole was cut at the south west corner of the carriage during the night shift. The following day, the other three holes for the safety pin brackets were torched in the northwest, northeast and southeast columns. The bracket plates were also welded to the steel columns. The bracket plate at the southwest end corner was welded during the night shift on December 28. All four safety pins were placed and the carriage was placed on the pins. Work proceeded on December 29 with the pins supporting the weight of the carriage. During the following night shift, some adjustments were made by slotting the holes to finalize the location of the safety pins, see figures 1 to 3.
On the morning of the day shift on December 30, two nylon chokers were attached to the decking carriage at the northwest corner, and to the lower shaft with a 1½ ton come-along positioned between the two chokers, see figure 4 and 5. It is believed that in addition to the dead load of the carriage, a force of 3,000 pounds was applied through the chokers to the safety pins. The carriage slipped from the safety pins and fell, pinning an employee. The slippage was caused by the failure of the welds of the bracket.
A structural engineer from the Directorate of Construction (DOC), OSHA National Office in Washington, D.C. visited the incident site on January 8, 2015, and examined the failure. The inspection revealed that there were multiple flaws in the installation of the bracket plate. The most notable flaw was the inferior quality of the welds due to an unacceptable weld profile and a lack of fusion, see figures 6 to 10. Moreover, the bottom of the plate was not even welded. The second flaw was the oversized hole made in the column plate which exacerbated the failure, see figures 11 and 12. If the hole had been only 1/16” larger than the diameter of the pin, the load could have been distributed to the ¾” column plate as well.
At the request of OSHA, KCAP retained an independent laboratory to examine the welds and provide a report (see Appendix). The report stated that the welds were inferior to the extent that they were not acceptable, and did not meet any applicable standards. DOC performed structural computations which indicated that even if the welds were done properly as per AWS standard, the dead load of the carriage with the additional force applied by the come-along would still have compromised the bracket. However, in the present case, because the welds were inferior and lacked fusion, and with a weld at the bottom of the plate completely missing, the dead load of the carriage with or without the additional force of the come along would have caused a failure of the bracket.
The following conclusions were made:
- The failure occurred due to the inferior quality of the welds on the bracket plate welded to the column. The welds were found to be unacceptable by an independent laboratory, which examined the welds.
- The hole in the column plate was made larger than required, thus excluding the possibility of distributing the load to the column flange plate.
- The welds were performed by non-certified AWS welders. One of the welders who performed the weld that failed had limited experience in welding.
- The Ford Kansas City Assembly Plant through its consultant failed to exercise due diligence by not ensuring that the work was performed as per industry standards.
- There was a lack of supervision on the part of the consultant retained by the Ford Kansas City Assembly Plant as there was a window of approximately 48 hours during which the welds could have been examined. Even a cursory examination of the welds would have indicated the inferior quality of the welds.
- If the welds had been properly performed in accordance with the applicable codes, this incident would not have occurred.
Weld Inspection Report
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