L51732 Fitness for Purpose Assessment Procedures for Sleeve Welds in Pipelines-Summary Report

Weld flaw acceptance criteria in the main body of the API 1104 pipeline code-Welding of Pipelines and Related Facilities is based on 'good workmanship' criteria. In allowing relaxed flaw acceptance criteria, the achievement of a critical CTOD value ensures that the flaws will remain stable during installation and service. This document presents alternative flaw acceptance criteria for pipeline girth welds which are based on the philosophy of fitness-for-purpose. The alternative flaw acceptance criteria can be applied in situations where specified minimum fracture toughness values are achieved in crack tip opening displacement (CTOD) tests performed on specimens notched into both the weld metal and heat-affected zone (HAZ). The alternative flaw acceptance criteria presented in Appendix A of API 1104 are restricted specifically to pipeline girth welds. In comparison, the flaw acceptance criteria in API RP1107-Recommended Pipeline Maintenance Welding Practices-which deals with pipeline sleeve welds are based entirely on 'good workmanship' standards.