API 5CT R95 oil casing is a high-strength seamless steel pipe that meets the American Petroleum Institute (API) SPEC 5CT standard and has a yield strength grade of R95. It is mainly used as a casing and tubing in oil and gas extraction projects in deep and ultra deep wells.
This steel grade belongs to high-strength and corrosion-resistant materials suitable for environments, with good comprehensive mechanical properties and certain resistance to hydrogen sulfide (H ₂ S) stress cracking. It is suitable for harsh working environments under moderate sulfur-containing conditions.
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API 5CT R95 Seamless Casing Pipe Specification
| Item | Description |
|---|---|
| Standard | API SPEC 5CT "Specification for Casing and Tubing" |
| Grade | R95 |
| Product Type | Seamless Steel Pipe |
| Application | Casing and Tubing for Oil & Gas Wells |
| Product Specification Level (PSL) | PSL-1 / PSL-2 / PSL-3 (as specified) |
| Manufacturing Process | Hot-rolled or cold-drawn seamless, normalized or quenched & tempered |
| Certification | API Monogram, ISO 11960, GB/T 19830 |
Chemical Composition of API 5CT R95 Casing & Tubing
| Element | Requirement (%) | Notes |
|---|---|---|
| Carbon (C) | ≤0.45% | Controls hardenability and crack resistance |
| Manganese (Mn) | ≤1.90% | Enhances strength and toughness |
| Silicon (Si) | ≤0.45% | Deoxidizer, improves strength |
| Phosphorus (P) | ≤0.020% | Harmful element, strictly limited |
| Sulfur (S) | ≤0.015% | Causes hot shortness, tightly controlled |
| Chromium (Cr) | ≤1.50% | Improves corrosion resistance |
| Molybdenum (Mo) | 0.25–0.85% | Increases high-temperature strength and HIC resistance |
| Nickel (Ni) | ≤0.99% | Enhances low-temperature toughness |
| Vanadium (V), Niobium (Nb), Titanium (Ti) | Trace additions | Grain refinement and precipitation strengthening |
Mechanical Properties of API 5CT R95 Casing & Tubing
| Property | Requirement |
|---|---|
| Minimum Yield Strength (YS) | ≥655 MPa |
| Tensile Strength (TS) | ≥758 MPa |
| Elongation (A) | ≥18% (50mm gauge) or ≥16% (4D gauge) |
| Hardness | ≤30 HRC (required for PSL-2/PSL-3 in sour service) |
| Charpy V-notch Impact Toughness | PSL-2: Avg ≥40J at -20°C (single ≥34J) |
API 5CT R95 Casing & Tubing Size Chart
| Outside Diameter (OD) | Common Sizes (inches) | Metric Range (mm) | Wall Thickness Range | Length Grade |
|---|---|---|---|---|
| Tubing (small diameter) | 1.05–4.5 in | 26.67–114.3 mm | 3.18–12.7 mm | R1, R2, R3 |
| Casing (medium/large) | 4.5–20 in | 114.3–508 mm | 6.35–22.2 mm | R2, R3 |
| Standard Lengths | - | - | - | R1: 4.88–7.62m R2: 7.62–10.36m R3: 10.36–14.63m |
API 5CT R95 Casing Tubing Production Tolerances
| Parameter | Allowable Deviation |
|---|---|
| Outside Diameter (OD) | |
| - D ≤ 114.3 mm | ±0.79 mm |
| - D ≥ 114.3 mm | +1.0% / -0.5% |
| Wall Thickness (WT) | -12.5% (no positive tolerance, controlled by weight) |
| Weight | Single pipe: +6.5% / -3.5%; Full shipment: ±1.75% |
| Length | R1: 4.88–7.62m; R2: 7.62–10.36m; R3: 10.36–14.63m |
| Straightness | ≤3mm per meter, total ≤0.2% of total length |
Testing Methods for API 5CT R95 Casing & Tubing
| Test Item | Requirements and Methods |
|---|---|
| Tensile Test | Sample per batch; measure YS, TS, elongation |
| Flattening Test | For welded or formed pipes (optional for seamless) |
| Hydrostatic Test | Performed on every pipe; pressure ≥80% of minimum collapse resistance |
| Non-Destructive Testing (NDT) | Ultrasonic Testing (UT) or Eddy Current (ET); mandatory for PSL-2+ |
| Impact Test | Required for PSL-2+ at -20°C with Charpy V-notch |
| Hardness Test | Minimum 3 points per pipe body; must be ≤30 HRC (for sour service) |
| Metallographic Analysis | Check for uniform microstructure and absence of banding/segregation |
API 5CT R95 Petroleum Casing Pipe Connections (Thread Types)
| Connection Type | Full Name | Application |
|---|---|---|
| SC | Short Round Thread Casing | Standard casing for shallow to medium-depth wells |
| LC | Long Round Thread Casing | Improved sealability, suitable for high-pressure wells |
| BC | Buttress Thread Casing | Highest tensile and compressive strength, used in deep wells |
| NU | Non-Upset Tubing | Plain-end tubing, constant OD, for shallow tubing strings |
| EU | External Upset Tubing | External upsets enhance joint strength, for medium-depth wells |
| IJ | Integral Joint Tubing | No coupling, lower flow resistance, ideal for high-productivity wells |
API 5CT R95 OCTG Pipe Factory
API 5CT R95 Oil Casing test and inspection
FAQ
R95 vs. L80
L80 is a medium to high strength steel grade with a minimum yield strength of 552 MPa, suitable for conventional oil and gas wells; R95 belongs to the high-strength steel grade, with a minimum yield strength of 655 MPa, making it more suitable for deep wells, ultra deep wells, and complex stress environments.
R95 vs. P110
P110 is currently the strongest conventional steel grade with a minimum yield strength of 758 MPa, mainly used in deep wells and high crush resistance scenarios; Although R95 (655 MPa) has slightly lower strength, it has better toughness and fatigue resistance, making it more suitable for complex stress and dynamic load environments.
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