Q125 is a high-strength steel grade in the API 5CT standard, and the "125" in its name represents a minimum yield strength of 125000 psi (approximately 862 MPa). It is suitable for deep wells, ultra deep wells, and oil and gas extraction scenarios that require extremely high material strength.
Q125 high-strength steel casing: yield strength 862-1034MPa, resistant to deep well high pressure/corrosion. Inquire for free downhole working condition adaptation solutions!
API 5CT Q125 Oilfield Casing Pipes Specification
| Item | Requirement |
|---|---|
| Standard | API SPEC 5CT (11th Edition, published Dec 2023) |
| Grade | Q125 |
| Manufacturing Process | Seamless (S) or Electric Welded (E); seamless preferred |
| Heat Treatment | Full-length Quenching & Tempering (Q&T) mandatory |
| NDT Requirements | Two methods required (e.g., EMI + UT) |
| Impact Testing | Required per heat/batch |
| Traceability | Full serialization required for Q125 |
| Application | Deep/ultra-deep wells, high-stress environments |
API 5CT Q125 Tubing Mechanical Properties
| Property | Requirement |
|---|---|
| Minimum Yield Strength | 862 MPa (125,000 psi) |
| Maximum Yield Strength | 1,034 MPa (150,000 psi) |
| Minimum Tensile Strength | ≥931 MPa (135,000 psi) |
| Total Elongation | ≥0.650% |
| Impact Energy (0°C) | Transverse ≥60J, Longitudinal ≥100J |
| Hardness Test | Quadrant hardness testing required; no fixed limit, but readings must be consistent |
API 5CT Grade Q125 Casing Tubing Steel Color Code
| Grade | Color Marking |
|---|---|
| Q125 | Purple band + White band (double stripe) |
API 5CT Q125 Oil Well Drilling Tube Chemical Composition
| Element | Max Content (%) | Purpose |
|---|---|---|
| Carbon (C) | ≤0.35 | Balances strength and ductility |
| Manganese (Mn) | ≤1.35 | Enhances strength and wear resistance |
| Molybdenum (Mo) | ≤0.85 | Improves hardenability and high-temperature strength |
| Chromium (Cr) | ≤1.50 | Increases corrosion resistance |
| Nickel (Ni) | ≤0.99 | Improves low-temperature toughness |
| Phosphorus (P) | ≤0.020 | Harmful impurity, strictly controlled |
| Sulfur (S) | ≤0.010 | Forms inclusions, affects SCC resistance |
| Silicon (Si) | - | Trace deoxidizer |
API 5CT Q125 Casing Tubing Size Chart
| Nominal Size (in) | OD (mm) | Common Wall Thickness (mm) | Application |
|---|---|---|---|
| 2 3/8" | 60.3 | 4.85, 5.21, 6.45 | Tubing |
| 2 7/8" | 73.0 | 5.51, 6.53, 7.11 | Tubing |
| 3 1/2" | 88.9 | 6.45, 7.34, 9.53 | Tubing/Casing |
| 4 1/2" | 114.3 | 6.88, 8.56, 11.43 | Casing |
| 5" | 127.0 | 7.52, 9.19, 11.51 | Casing |
| 5 1/2" | 139.7 | 7.72, 9.17, 11.43 | Casing |
| 7" | 177.8 | 8.05, 9.19, 12.65 | Casing |
| 9 5/8" | 244.5 | 9.53, 11.05, 13.84 | Casing |
| 13 3/8" | 339.7 | 9.65, 11.10, 12.70 | Casing |
API 5CT Q125 OCTG Casing Tolerance
| Parameter | Allowable Deviation |
|---|---|
| Outer Diameter Tolerance | |
| ≤101.60 mm | ±0.79 mm |
| ≥114.30 mm | +1.0% / -0.5% |
| Wall Thickness Tolerance | 0 to -12.5% |
| Length Classification | |
| Casing | R1: 4.88–7.62m; R2: 7.62–10.36m; R3: 10.36–14.63m |
| Tubing | 6.10–9.75m (standard) |
API 5CT Q125 Petroleum Casing Pipe Connections
| Connection Type | Abbreviation | Description |
|---|---|---|
| Short Round Thread Casing | SC | Standard for low-pressure service |
| Long Round Thread Casing | LC | Higher strength than SC |
| Buttress Thread Casing | BC | High-pressure, high-tension service |
| Non-Upset Tubing | NU | Plain-end tubing |
| External Upset Tubing | EU | Thickened end for better connection strength |
| Integral Joint | IJ | No separate coupling, integral thread |
Q125 Casing Heat Treatment
| Parameter | Requirement |
|---|---|
| Process | Full-length Quenching & Tempering (Q&T) |
| Purpose | Achieve tempered martensite/bainite structure for optimal strength-toughness balance |
| Prohibited | Normalizing (N) or Normalizing + Tempering (N&T) alone |
| Hardness Control | Quadrant testing; data variation must be within acceptable limits |
| QC Equipment | Hardness gradient tester and impact tester required |
API 5CT Q125 OCTG Factory
API 5CT Q125 Casing Pipe certificate
FAQ
What is the length of API 5CT R2?
The API 5CT R2 ranges in length from 8.23 meters to 9.14 meters (27 to 30 feet).
What is the difference between API 5B and 5CT?
API 5B and API 5CT are two complementary but clearly defined core standards in the oil and gas industry: API 5CT specifies the material and performance of the pipe body itself, while API 5B specifies the size and inspection of threaded connections.
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