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The Case of the Collapsing Chair

Exemplar Chairs	The Problem:

The elderly plaintiff sat onto a restaurant chair and the chair collapsed.  As a result of the failure the plaintiff unexpectedly fell to the floor and was hurt. The plaintiff sustained debilitating injuries to the hip, spine, neck and arm.  Failed welds at the chair legs caused the chair to give way.  The chair was not fit for service on un-level floors or public use.  When subjected to normal conditions at an eatery, the welds from the chair manufacturer, did not fulfill the fundamental purpose of seating for a normal-sized person.

My Assessment: 

On exemplar chairs, the welds were visually examined and metallurgical assessments were conducted. The exemplar chairs and subject chairs had welds there were structurally deficient, deformed, broken and poor quality. The welds did not comply with any welding standards-of-care.  The welds failed during anticipated routine use.  The weld configurations were Flare Vee Groove-Corner Joint and Fillet Weld. These designs were inappropriate for thin sheet-steel, channel members.  Structurally, the weld joint  connections were not a safe design.  

Failed Weld Front Leg of ChairThe Consequences: 

The defendant purchased the chairs to provide reliable and comfortable seating for any occupant while dining at the restaurant.  The welds did not comply with any structural welding code.  The joint configuration was unstable and there was no redundancy for safety.  The workmanship of the welds did not achieve industry standards. There were obvious discontinuities, insufficient weld penetration and the surface integrity of the welds was unreliable.  The chair manufacturer’s labels did not warn the owner about in-service inspections of the welds.  The manufacturer’s labels did not describe actions to take when broken welds were located.

Failed Weld, Back Leg of ChairThe Lessons Learned:

The flaws in the welds could have been easily observed before the chairs were shipped from the factory and with routine visual inspections by the owner of the eatery.  Damaged and broken chairs should be removed from service.  Repair or discard decisions were always the chair owner’s duty, either at the factory or the restaurant.

 

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Welding Failures I Have Known, Interesting cautionary tales from Metals & Welding  expert, Dr Jesse A Grantham, PE