Summary
When a crack or crack-like defect turns up in a pressurized steel cylinder, operators need fast, defensible answers: can the asset stay in service, at what pressure, and for how long? Structural Integrity Associates (SIA) developed APTITUDE™, a crack feature evaluation tool that calculates a predicted failure pressure (PFP) and remaining life for cracks in pipelines and other pressurized cylinders, supporting safety, regulatory compliance, and asset optimization.
Every fracture mechanics method carries its own limitations, boundary conditions, and conservatisms, so APTITUDE applies several accepted approaches, including the Modified Ln-Secant equation, Failure Assessment Diagram (FAD) analysis using API 579 and MAT-8 methods, and a finite element–based limit load approach. It then recommends the most appropriate method for the pipe, flaw, and material at hand. The tool handles a broad range of yield strength, flow stress, and fracture toughness values, as well as through-wall and surface cracks of varying length, depth, and orientation, and can use measured material properties or Charpy V-Notch correlations when available.
Pipeline operators use APTITUDE to satisfy the predicted failure pressure requirements of 49 CFR §192.712, evaluate stress corrosion cracking and ERW long seam weld defects, prioritize in-line inspection crack tool results, and set reassessment intervals through remaining life models for SCC, fatigue, and linear crack growth. The same analysis supports MAOP reconfirmation through an Engineering Critical Assessment (ECA). Developed further through a joint industry project, the platform is now web-based and is being applied to crack evaluation in hydrogen blending environments.
SIA pairs the software with hands-on expertise. Pipeline teams can draw on SIA’s pipeline integrity services, while owners of vessels and cylinders can turn to Pressure Systems Engineering for fitness-for-service and life cycle support. SIA’s advanced engineering group brings fracture mechanics and remaining life evaluation to complex problems, and the Metallurgical Laboratory verifies material properties and investigates failure causes. Contact SIA to discuss how APTITUDE can turn crack indications into confident, compliant decisions.