ISO 15590-2:2021

This document specifies the technical delivery conditions for unalloyed or low-alloy steel seamless and welded pipeline fittings for use in pipeline transportation systems for the petroleum and natural gas industries as defined in ISO 13623.
This document is applicable to welding-end fittings such as elbows, caps, tees, single or multiple extruded headers, reducers, and transition sections made from seamless and welded pipe of unalloyed or low-alloy steels.
This document specifies two classes of fitting one related to material used in non-sour service and one for material to be use in sour service environment as shown in Table 1.
This document is not applicable to the selection of the fitting class.
This document is not applicable to the materials for, or the attachment of, factory-welded extensions.