API 5CT C90 Type1 Casing For Sour Service
API 5CT C90-1 casing for sour service is a high-strength seamless steel pipe specifically designed to resist sulfide stress corrosion cracking (SSC) in harsh, H₂S-rich environments, making it ideal for deep and ultra-deep sour wells. This grade complies with NACE MR0175/ISO 15156 standards and is widely used in high-pressure, high-temperature (HPHT) wells with elevated partial pressures of hydrogen sulfide.
Specializing in sour service! API 5CT C90-1 casing delivers top-tier sulfide stress corrosion cracking (SSCC) resistance, safeguarding your oil & gas operations-inquire now for a custom quote!
API 5CT C90-1 Casing Steel Pipe Specifications
Standard: API 5CT / ISO 11960 / NACE MR0175
Application: Sour oil and gas service (H₂S > 0.3 kPa)
Temperature Limit: <65°C (Type 1)
Certification: EN 10204 3.1/3.2 available
API 5CT C90-1 OCTG Casing Color Code
Per API 5CT, C90-1 casing is marked with one purple band on the pipe body for quick field identification.
API 5CT C90-1 Petroleum Casing Pipe Chemical Composition
C90-1 is a low-alloy steel with tightly controlled chemistry to enhance SSC resistance:
| Element | Requirement (%) |
|---|---|
| Carbon (C) | ≤0.35 |
| Manganese (Mn) | 0.25–1.20 |
| Molybdenum (Mo) | 0.40–0.85 |
| Chromium (Cr) | 0.80–1.50 |
| Phosphorus (P) | ≤0.010 |
| Sulfur (S) | ≤0.005 |
| Nickel + Copper (Ni+Cu) | ≤0.99 |
| Vanadium (V), Titanium (Ti), Aluminum (Al) | Trace additions for grain refinement |
API 5CT C90-1 Oilfield Casing Mechanical Properties
| Property | Requirement |
|---|---|
| Yield Strength | 621–724 MPa (90–105 ksi) |
| Tensile Strength | ≥689 MPa (100 ksi) |
| Minimum Elongation | ≥10% (50.8 mm gauge length) |
| Hardness Limit | ≤25 HRC or ≤255 HBW, uniform across wall thickness |
API 5CT C90-1 Casing for Sour Service Dimensions & Size Chart
Standard outside diameters (OD) and wall thicknesses (WT) per API 5CT:
| OD (mm/inch) | WT (mm/inch) | Size Designation |
|---|---|---|
| 114.3 mm (4.5") | 6.88–9.17 mm | 4-1/2" Reg |
| 139.7 mm (5.5") | 7.72–11.51 mm | 5-1/2" Reg |
| 177.8 mm (7") | 8.05–13.72 mm | 7" Reg |
| 244.5 mm (9-5/8") | 9.19–13.84 mm | 9-5/8" Reg |
| 339.7 mm (13-3/8") | 9.65–15.90 mm | 13-3/8" Reg |
API 5CT C90-1 OCTG Casing Tolerances
OD Tolerance: ±0.75% to ±1.0%
WT Tolerance: +12.5% / -10%
Length (R1/R2/R3): 4.88–7.62 m / 7.62–10.36 m / >10.36 m
API 5CT C90-1 Casing Steel Pipe Tensile & Hardness Requirements
Minimum Tensile Strength: 689 MPa (100,000 psi)
Yield Strength Range: 621–724 MPa (to balance strength and ductility)
Total Elongation: ≥0.5% (post-yield plastic deformation)
Maximum Hardness: 25 HRC or 255 HBW, measured at multiple points across the section
API 5CT C90-1 Petroleum Casing Pipe, Features
- High strength with excellent toughness
- Superior resistance to SSC (sulfide stress cracking)
- Good hardenability and tempering stability
- Fine-grained microstructure (ASTM ≥5)
- Suitable for use in H₂S environments with partial pressure >0.3 kPa
API 5CT C90-1 Oilfield Tubing Manufacturing Process
- Raw Material: High-purity electric arc or basic oxygen furnace steel billets
- Forming Method: Seamless via rotary piercing and rolling (e.g., CPE mandrel mill)
- Finishing: Cold sizing or stress relieving as required
API 5CT C90-1 Oil Well Drilling Casing Pipe Heat Treatment
Process: Quenching + High-Temperature Tempering
Quenching Temperature: ~900°C
Tempering Temperature: 600–680°C
Microstructure Achieved: Uniform, fine tempered sorbite
Purpose: Ensure stable mechanical properties, refined grains, and controlled hardness
API 5CT C90-1 Oil Tubing Testing Requirements
Each heat batch must undergo the following key tests:
Tensile Test: Verify yield and tensile strength
Hardness Test: Multiple points across the cross-section
Impact Test: Required for projects in cold regions
SSC Test (NACE TM0177 Method A): Load at 80% SMYS in simulated sour environment for 720 hours - no cracking allowed
Hydrostatic Test: 100% of pipes tested at pressure ≥ minimum specified internal yield pressure
Metallographic Analysis: Confirm grain size finer than ASTM 5
API 5CT C90-1 Oil And Gas Casing Pipes Applications
- Sour oil and gas zones in deep and ultra-deep wells
- High H₂S partial pressure gas wells
- HPHT (High Pressure High Temperature) well conditions
- Unconventional resources: coalbed methane, shale gas
API 5CT Casing for Sour Service supplier
Verified API 5CT Casing Steel Pipe
Boost efficiency from the right casing choice! API 5CT C90-1, engineered specifically for sour service, perfectly matches extreme conditions. Inquire now and get a free material test report!
FAQ
What is the OD tolerance of API 5CT
The outer diameter (OD) tolerances for API 5CT C90-1 are: ±0.79 mm when the outer diameter is less than 4½ inches (114.3 mm); and +1%/-0.5% of the nominal outer diameter when the outer diameter is greater than or equal to 4½ inches.
What is the range of API 5CT
API 5CT C90-1 casing has an outer diameter ranging from 114.3 mm (4½ inches) to 339.7 mm (13⅜ inches), a wall thickness ranging from 6.88 mm to 15.90 mm, and can be customized in R1, R2, and R3 grades (4.88–12.5 meters and above).
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