Abstract: Described here in the assey are the major information concerning R & D of the Φ406.4 mm×19.1 mm X65MO HFW linepipe for marine service,and the inspection criteria for it.The results of relevant tests to the said linepipe show that all the technological and quality target values thereof are in conformity to both the applicable technical specification for Submarine Pipeline Systems(DNV-OS-F101—2007) and the end-user's techncial spec-ification as well.The product has been so far successfully used for a domestic submarine oil/gas pipe line project as being performed in a shallow sea area.