The steel grades of tubing are H40, J55, N80, L80, C90, T95, P110.
N80 is divided into N80-1 and N80Q. The similarities between them are the same in tensile properties, while the differences between them are the difference in delivery status and impact properties. When N80-1 is delivered in normalized condition or when the finishing rolling temperature is higher than the critical temperature Ar3 and the tension reduces diameter and passes through air cooling, hot rolling can be used instead of normalizing. The impact power and non-destructive testing are not required. N80Q must undergo quenching and tempering heat treatment. Impact work should comply with API 5CT regulations and non-destructive testing should be carried out.
C90 and T95 are divided into 1 types and 2 types, namely C90-1, C90-2 and T95-1, T95-2.