Flange Quality Investigation to Prevent Brittle Fracture

A quality investigation was done on ASTM A350 flanges after discovery of unauthorized repairs for a deepwater project in the Gulf of Mexico. The investigation also revealed low Charpy impact values which can potentially cause brittle fracture at low service temperatures. Therefore, additional flanges from the same supply chain (various manufacturers) were quarantined and tested by the destructive Charpy impact method as well as by the non-destructive Automated Ball Indentation (ABI) method. Based on the results of the quarantined flanges, the remaining flanges that were already installed were deemed fit for service. ABI method was evaluated regarding its capability of measuring fracture toughness non-destructively. Actions were taken by other Deepwater projects to prevent brittle fracture, in terms of material specification, supply chain management and material property verification.