Assessment of Pipeline Crack and Crack-like Colonies - A Case Study
(Room Conference Hall)
04 Apr 18
9:30 AM
-
11:00 AM
T.D. Williamson (TDW) inspected a 10 inch transmission line in Canada using Deformation (DEF), Multiple Dataset (MDS) and Electro-magnetic Acoustic Transducer (EMAT) In-Line Inspection tools. The data from the tools were used in an immediate defects assessment to establish the criticality of crack-like defects on their pipeline and assess the feasibility of increasing the Maximum Allowable operating pressure (MAOP) of the line. From the in-line inspection (ILI) data, 13 Linear Indication defects were reported in the preliminary EMAT Report, with three reported as axial crack-like colonies in the pipe body and 10 reported as axial crack-like defects in the long seam. A failure pressure calculations was applied to these defects utilizing the latest fracture mechanics model from Battelle Memorial Institute, using their software PipeAssess PI™, which was developed under a DOT PHMSA research contract. The assessment was made more complicated by the unknown crack geometry, large crack lengths, and the customer’s limited knowledge of the pipeline’s material properties. However, a solution was developed to report failure pressures for each defect using a range of material toughness values and crack assessment categories. Ultimately, a defect assessment report was generated for the customer with the main deliverable being a list of the reported crack-like defects in order of severity with respect to their predicted failure pressure, along with recommendations for how to verify the EMAT findings and associated failure pressure calculations. The assessment and recommendations were leveraged by the customer to determine how to proceed with investigating the defects and preparing their line for a higher MAOP. The paper presents the tools that were applied, the assessment models, the results and benefits to the operator of the project.