Effect of interaction between corrosion defects on failure pressure of thin wall steel pipeline

• Finite element models are validated to study the interaction of corrosion defects.
• An interaction rule of corroded pipeline under internal pressure is proposed.
• The proposed rule can identify the interaction more accurately than the others.

The finite element models of corroded pipelines with colony of defects composed of two longitudinal or circumferential aligned defects, and four defects arranged in rhombus shape are established and validated, respectively. Considering the different longitudinal and circumferential spacings between defects, the cases related to 13 types of colony of defects are computed. Based on the ratio of failure pressure of each case to the failure pressure of corresponding base case, the interaction between defects is determined. Then a new interaction rule is proposed. Compared with the performance of DNV RP F101, the API 579, the BS 7910, the Kiefner and Vieth, and the Pipeline Operator Forum (POF) interaction rules which are applied to FE cases, the proposed rule could satisfactorily identify whether or not the interaction between defects occurs.