X80is the number in the American Petroleum Institute's API Spec 5L Pipeline Specification. X represents the pipeline steel in the API Spec 5L standard, 80 is the strength grade, the unit is kpsi, and X80 is the pipeline steel with a minimum yield strength of 80 kpsi, which is converted to a metric unit of approximately 555 MPa.

Chemical composition (%)
C	Si	Mn	P	S	Cr	Ni	Ti	Nb	V	Mo
0.063	0.28	1.83	0.011	0.0006	0.03	0.03	0.016	0.061	0.059	0.22

The X80 is an American classification of high strength pipeline steel. The minimum yield value (MPa) is 555; this concept belongs to the concept of material mechanics. The yield value refers to the stress value at the yield stage when the material is stretched, and the yield stress refers to the critical value of the yield stage to the contraction stage.

Since the X80 strength grade line pipe belongs to the high steel grade product in the pipeline pipe, the strength requirement of the steel pipe is high, and the PSL2 technical grade product limits the product strength, that is, the yield strength is 555~705MPa, and the tensile strength is 625~825MPa. And there is a limit on the yield ratio, the requirement is not higher than 0.93.