API Q125 Casing vs API P110 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 Q125 Casing
Pipe & Tube Steel
Q125 is the top standard strength grade in API 5CT: a 125 ksi yield casing for ultra-deep and high-pressure wells where even P110 cannot carry the string weight or burst load. It is a mill-produced Q&T product, bought to performance rather than chemistry.
Standards: AISI API 5CT Q125 · GB Q125 (GB/T 19830)
API P110 Casing
Pipe & Tube Steel
P110 is the high-strength API 5CT casing grade for deep, high-pressure wells where collapse and burst loads exceed L80 capability. It is a Q&T product with a wide 110–140 ksi yield band and is not rated for sour service.
Standards: AISI API 5CT P110 · GB P110 (GB/T 19830)
Chemical composition compared (%)
| Element | API Q125 Casing | API P110 Casing |
|---|---|---|
| P | ≤0.030 | ≤0.030 |
| S | ≤0.030 | ≤0.030 |
| Note | API 5CT sets no C/Mn limits for Q125 — chemistry is mill practice, delivery is quenched & tempered | Chemistry is mill practice (typically Cr-Mo Q&T) |
Properties compared
| Property | API Q125 Casing | API P110 Casing |
|---|---|---|
| Yield strength | 862–1034 MPa (125–150 ksi) | 758–965 MPa (110–140 ksi) |
| Tensile strength | ≥931 MPa (135 ksi) | ≥862 MPa (125 ksi) |
| 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 Q125 Casing · API P110 Casing. Substitution decisions for certified parts stay with the design authority.