API 5CT C90 Casing Tubing
API 5CT C90 acid resistant tubing is a high-strength, hydrogen sulfide corrosion resistant (SSC) oil well casing designed specifically for sulfur-containing oil and gas wells, suitable for deep and ultra deep well operations in highly acidic environments.
This product complies with the American Petroleum Institute API 5CT standard and meets corrosion resistance specifications such as NACE MR0175/ISO 15156. It is widely used in harsh working conditions where H ₂ S and CO ₂ coexist.
Frequent failure of deep well casing? API 5CT C90 acid resistant tubing, yield strength 655-758MPa, anti extrusion performance exceeding API standards by 15%, inquiry for customized wellbore structure solutions!
API 5CT C90 Oilfield Casing Color Code (Color Marking)
Used for on-site identification of the grade:
Outer surface: One green band + One brown band
Marking position: At least 0.6 meters from the pipe end, with clear and visible paint marking
API 5CT C90 Casing for Sour Service Chemical Composition
| Element | Content (%) | Purpose |
|---|---|---|
| C | 0.26–0.35 | Ensures strength and hardenability |
| Si | 0.17–0.37 | Deoxidation and matrix strengthening |
| Mn | 0.40–0.70 | Increases strength and toughness |
| Cr | 0.80–1.10 | Enhances corrosion resistance and hardenability |
| Mo | 0.15–0.25 | Improves tempering stability and SSC resistance |
| S | ≤0.005 | Strictly limited to prevent sulfide inclusions causing SSC |
| P | ≤0.020 | Reduces cold brittleness tendency |
| Als | ≥0.020 | Refines grain size, improves toughness |
API 5CT C90 Casing Tubing Mechanical Properties
| Property | Requirement |
|---|---|
| Yield Strength | 655–758 MPa |
| Tensile Strength | ≥758 MPa |
| Elongation | As per table (based on wall thickness and outer diameter) |
| Hardness | ≤248 HB / ≤25 HRC |
| SSC Resistance | Must pass NACE TM0177 Method A (Solution A, stress at 90% YS) |
API 5CT C90 Petroleum Casing Pipe Size Chart
| OD (in) | OD (mm) | Wall Thickness (mm) | Weight (kg/m) | Application |
|---|---|---|---|---|
| 4.5 | 114.3 | 8.56 | 24.7 | Medium-depth wells |
| 5.5 | 139.7 | 9.17 | 32.8 | Main casing string |
| 7 | 177.8 | 10.36 | 48.3 | Deep wells |
| 9 5/8 | 244.5 | 11.05 | 64.0 | Surface/intermediate casing |
| 13 3/8 | 339.7 | 12.19 | 97.2 | Large-diameter sections |
API 5CT C90 Oil Well Drilling Tube Tolerance Requirements
| Item | Allowable Deviation |
|---|---|
| Outer Diameter (D ≥ 114.3 mm) | +1.0% / -0.5% |
| Wall Thickness | +6.5% / -12.5% |
| Length (R2: 8.23–9.14 m) | ±0.05 m |
| Single Pipe Weight | ±3.5% |
| Straightness | ≤3 mm/m |
API 5CT C90 Casing Pipe Inspection Requirements
Each batch of C90 corrosion-resistant pipe must undergo the following inspections:
Chemical Analysis (Heat analysis and product analysis)
Tensile Test (Yield, tensile strength, elongation)
Hardness Test (At least two points per pipe)
Impact Test (Charpy V-notch, -20°C or lower)
Hydrostatic Test (Test pressure ≥ 1.5× nominal pressure)
Non-Destructive Testing (NDT):
Full-length ultrasonic testing (UT) or radiographic testing (RT)
Magnetic particle testing (MT) on thread areas
SSC Test (Conducted per NACE TM0177, simulating sour environment)
API 5CT C90 Pipe Connections (Common Thread Types)
Common thread types for C90 casing include:
STC (Short Round Thread Coupling): Short round thread, widely used
BTC (Buttress Thread Coupling): Buttress thread, better tensile and sealing performance
LTC (Long Round Thread Coupling): Long round thread, suitable for medium-high pressure
VAM, Hydril, etc. premium threads: Gas-tight connections for high-pressure, high-acidity environments
API 5CT C90 OCTG pipe factory
API 5CT C90 Oil well casing pipe certificate
FAQ
What does API 5CT mean?
API 5CT is the authoritative technical standard for oil well casing and tubing in the global oil and gas industry, published by the American Petroleum Institute (API) as the "Casing and Tubing Specification".
What is the difference between API 5CT and API 5L?
The core difference between API 5CT and API 5L lies in their application areas and product types: API 5CT specifies the casing and tubing used inside oil wells, while API 5L specifies the pipeline tubing used for long-distance transportation of oil and gas.
Although both are developed by the American Petroleum Institute (API) and some manufacturing processes and material standards overlap, they target products at different stages of the oil and gas industry chain, with significant differences in technical requirements and usage scenarios.
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