API C90 Casing vs API T95 Casing
These two grades are listed as equivalents of each other: their chemistry windows overlap and they serve the same applications. They are not always identical — check the differences below before substituting, especially in certified designs.
API C90 Casing
Pipe & Tube Steel
C90 is a controlled-hardness API 5CT grade for sour (H₂S) wells: quenched-and-tempered to a 90 ksi yield window while the hardness is capped at 25.4 HRC so sulfide stress cracking cannot start. It is specified where N80-type material would be an SSC risk.
Standards: AISI API 5CT C90 · GB C90 (GB/T 19830)
API T95 Casing
Pipe & Tube Steel
T95 is the stronger sibling of C90 in the API 5CT sour-service family: 95 ksi yield with the same 25.4 HRC hardness ceiling and sulfide-stress-cracking test regime. It serves deep sour wells where C90’s strength runs out but P110-class hardness would be an SSC hazard.
Standards: AISI API 5CT T95 · GB T95 (GB/T 19830)
Chemical composition compared (%)
| Element | API C90 Casing | API T95 Casing |
|---|---|---|
| P | ≤0.030 | ≤0.030 |
| S | ≤0.030 | ≤0.030 |
| Note | API 5CT controls C90 by strength, hardness and SSC testing — no C/Mn composition limits | API 5CT controls T95 by strength, hardness and SSC testing — no C/Mn composition limits |
Properties compared
| Property | API C90 Casing | API T95 Casing |
|---|---|---|
| Yield strength | 621–758 MPa (90–105 ksi) | 655–758 MPa (95–110 ksi) |
| Tensile strength | ≥689 MPa (100 ksi) | ≥724 MPa (105 ksi) |
| Hardness | ≤25.4 HRC (sour-service cap) | ≤25.4 HRC (sour-service cap) |
| Density | 7.85 g/cm³ | 7.85 g/cm³ |
Sourcing either grade?
Nasteel stocks both families from Shenzhen with EN 10204 3.1 mill certificates by heat number.
Ask for a quotationSee full data sheets: API C90 Casing · API T95 Casing. Substitution decisions for certified parts stay with the design authority.