Analysis of causes of casing elevator fracture

A fracture accident occurred with a 244.5 mm–350 ton casing elevator and a traveling hook during casing running down. This paper gives an investigation of this accident, and analyzes the causes based on fracture surface examination and material tests. Some simulation tests are performed in order to validate the fracture mechanism. It is concluded that the casing elevator fracture originated from quenching cracks caused by surface carburization. Calculations of the fracture load acting on the casing elevator showed that the casing elevator broke first, resulting in hook fracture.