46th ed. API Spec 5L "Specification for Line Pipe".
Changes from the previous edition include the following:
•updated and expanded requirements for mill jointers (differentiate between double-jointers and mill jointers; avoid welding consumables environmental contamination; require qualification standards; new process testing requirements; clarify offset and undercut requirements; standardize marking requirements; reference weld repair annex);
•updated requirements for pipe end squareness; updated requirements for hardness testing on PSL 2 pipe for sour service and PSL 2 pipe for offshore service;
•a new annex for strain-based design requirements (PSL 2 pipe for applications requiring longitudinal plastic strain capacity).