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The Case of the Fatigued Chicken Feather Cooker

Rendering Cooker, End Rotor ForgingThe Problem:

The 12” solid, driveshaft rotor “broke off” a 20,000 lb cooker of chicken feathers at a remote, rendering plant. The final fracture surfaces were smooth and rippled with classic fatigue features.  Prior to failure, the shear pin broke during a lock up, however, the cooker assembly continued to rotate.   The rotor was a forging with a long driveshaft and pillow block bearings that supported the end of the cooker.  The forging was welded to the flat cooker vessel head.  It was reported that the cooker rotated erratically during final days of operation.  The pillow block bearings were small, damaged and fragmented.

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The Case of the 2000' Tall Collapsed Antenna Tower

Collapsed Steel Antenna TowerThe Problem:

Structural tower upgrades to the steel antenna tower were required to comply with FAA mandates about aviation lights and loads for high-definition TV antennae.  The work crew was replacing the existing diagonals with larger diagonals and new struts in specific tower panel locations near the top of the tower. The work was nearly completed prior to the tower collapse.

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The Case of the Gas Pipe Failures at Mountain Condos

The Case of the Gas Pipe Failures at Mountain Condos (2009254)The Problem:

Multi-family condominiums are common lodging for Rocky Mountain winter vacationers. Gas and electricity utilities sandwiched into open-spaces, between the parking lot and the condo building are vulnerable to damage from snow removal activities. Huge amounts of snow were pushed from the parking lot by the snowplow into the open-space.

The natural gas regulators for the condos were covered with snow and the pipe threads failed resulting in an explosion and fire.

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The Case of the Failed Windmill Ladder Rungs

Windmill generatorsThe Problem:

Workers climbing the ship–ladder inside a tower experienced oily walking surfaces and degraded ladder surfaces. The ladder rungs rotated freely when cradled in the side rails. The ship-ladder configuration was vertical and each ladder rung was plug-welded into both side rails. Plug-weld connections on the rungs were not sound and could not resist the inherent “rotating shear” when loaded by climbers.

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The Case of the Missing Rudder Access Plate on the Ocean-Going Container Vessel

Rudder and Access Plate to Pintle NutThe Problem:

The Scope of Work under the Plaintiff’s contract required the Shipyard to examine the starboard lower pintle pin and rudder stock nut.  The vessel’s rudder assembly was a Semi-Balanced Spade Type.

The access plate of the vessel’s rudder was removed to allow for the performance of a survey by the ABS. The ABS survey determined that weld repairs were necessary to a fracture in the Vessel’s rudder stock pintle pin nut.  After the final survey and pin repairs, the Shipyard re-welded the access plate onto the rudder.

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