1. The yield strength of N80-1/Q is 173 ~ 206 MPa higher than that of J55.
2. The elongation of N80-1/Q is higher than that of J55 on the same sample area.
3. With the same specification, the same sample orientation, and the same minimum sample size, the absorption energy of J55 steel couplings, coupling blanks, coupling materials, coupling blanks, and accessory materials is lower than that of N80-1/Q steel grades.
4. The non-destructive test methods for J55 and N80-1/Q seamless pipes, coupling blanks and welded pipe are different.
5. Steel grades of J55 and N80-1/Q are not the same: length is greater than or equal to 1.8m, J55 is painted bright green, N80-1 is painted red, N80-Q is painted red, bright green; the entire coupling The oil jacket of J55 is bright green, N80-1/Q is red, the ink ribbon of J55 is colorless, the casing of J55 is white, N80-1 is not, N80-Q is green.
6. The mark or symbol of the product grade is different: the symbol of J55 is “J”, the symbol of N80-1 is “N1”, and the symbol of N80-Q is “NQ”.
7. Different heat treatment processes for J55 and N80-1/Q:
J55: Select by the manufacturer, or according to the order regulations, full length normalizing (N), normalizing + tempering (N&T) or quenching and tempering (Q&T).
N80-1: Overall, full-length heat treatment is a mandatory requirement. Normally selected by the manufacturer for normalizing (N) or normalizing + tempering (N&T).
N80-Q: Quenching (Q)
8. The distance between the welded tube crush test plates is different.
9. Hydrostatic pressure test is different.
10. The requirements of PSL-2/3 differ between J55 and N80-1/Q.