Brittle fracture assessment of the API specification 12F shop welded flat bottom tanks

A brittle fracture evaluation is conducted to inquire the propensity of a material to fail without appreciable plastic deformation. In case of the API 12F tanks, several parameters such as ambient temperature, residual stresses, and material toughness can play significant roles in the behavior of the equipment. Complete 3D models of the current API 12F shop-welded, flat bottom tanks as well as axisymmetric and solid submodels were created to address the brittle fracture evaluation and determine whether these storage tanks can operate safely under extreme conditions. Through-wall and surface crack flaws were considered in the most critical joints of the storage tanks and toughness relative ratios between the response of the steel material and the acceptance criteria of the API 579 standard were calculated to describe the behavior of the equipment.