Office Chair Failure

Metallurgical failure analysis was necessitated as result of an office chair failure (see Photograph A). Visual and metallurgical examination revealed cracks in the office chair base.  Visual inspection revealed that the office chair had been previously cracked and the previous crack had been re-welded. Re-welding without removing the initial cracked metal is very poor repair practice. The re-weld base of the office chair is shown in Photograph B.

Photograph A  Overall view of subject office chair.

 
Photograph B  Close-up view of underside
 of re-welded office chair.

After additional usage of the repaired office chair, the weld repair also failed.  Normally re-welding of a metallurgical failure  will melt the original cracked metal and will make any meaningful metallurgical failure analysis impossible.  However, if the re-weld also fails, the possibility exists that significant metallurgical fracture evidence from the original cracking/failure event might be uncovered if the cracked weld is opened and evaluated. A metallurgical failure analysis and design evaluation was conducted.  However, in this matter, analysis of the failed office chair was concluded without metallurgical or weld testing. 

Photograph C  Close-up view of center line
 weld crack in re-welded office chair base.

Photograph D  Close-up view of cracking
 in re-welded office chair base.