1. The yield strength of N80-1/Q is 173-206 Mpa higher than that of J55.


2. In the same product area, the elongation of N80-1/Q is higher than that of J55.


3. The absorption energy of J55 steel cascade shaft, couplings blank, couplings material, semi-finished products of couplings and auxiliary materials is lower than that of N80-1/Q steel grade.


4. J55 and N80-1/Q seamless tubes have different non-destructive testing methods for connecting billet and welded tube.


5. The steel grade color codes of J55 and N80-1/Q are different: length greater than or equal to 1.8m, J55 painted bright green, N80-1 painted red, N80-Q painted red, a bright green; the whole coupling, J55 casing painted bright green, N80-1/Q painted red; ribbon, J55 pipe colorless, J55 casing white, N80-1 colorless, N80-Q green.


6. Signs or symbols of steel products are different: the symbol of J55 is "J", the symbol of N80-1 is "N1", and the symbol of N80-Q is "NQ".


7. The heat treatment processes of J55 and N80-1/Q are different:
J55: Selected by manufacturer or according to order, full length standardization (N), standardization + tempering (N&T) or quenching + tempering (Q&T).
N80-1: Comprehensive and long-term heat treatment is necessary. Manufacturer Standardization (N) or Standardization + Tempering (N&T)
N80-Q: Quenching (Q)


8. The distance between welded pipe and flattened test plate is different.


9. Hydrostatic pressure testing is different.


10. J55 and N80-1/Q require different PLL-2/3 requirements.