API 5CT L80 BTC Casing
API 5CT L80 BTC Casing is a high-performance steel pipe used in the oil and gas industry. According to API Spec 5CT, L80 belongs to Group 2 steel grades, characterized by controlled yield strength and hardness, making it suitable for environments containing hydrogen sulfide (H2S) (sour service).
L80 (Grade): A steel grade with a yield strength restricted between 80,000 psi and 95,000 psi. It is available in three types: L80-1 (Carbon steel), L80-9Cr (9% Chromium), and L80-13Cr (13% Chromium for high CO2 environments).
BTC (Buttress Thread Connection): A trapezoidal thread form (3°/10° load/stab angles, 5 threads per inch). It offers high tensile strength, nearly equal to the pipe body, making it ideal for deep wells and high-tension loads.
Over 500 global drilling projects rely on our L80 casing. Send us your tender or RFP and let us become your most reliable supply chain partner.
API 5CT L80 BTC OCTG Identification Color Band Table
API 5CT specifies color coding for field identification of steel grades.
| Grade | Pipe Body Color Band | Coupling Color | Remarks |
| L80-1 | 1 Red band | All Red (no band) | Standard L80 |
| L80-9Cr | 1 Red, 1 Brown band | All Red with 1 Brown band | Corrosion resistant |
| L80-13Cr | 1 Red, 1 Yellow band | All Red with 1 Yellow band | High corrosion resistant |
API 5CT L80 BTC Casing pipe Chemical Composition and Mechanical Properties
Chemical Composition (L80-1 Typical)
| Element | C (Max) | Mn (Max) | P (Max) | S (Max) | Si (Max) | Ni (Max) | Cr |
| Content % | 0.43 | 1.90 | 0.030 | 0.030 | 0.45 | 0.25 | - |
Mechanical Properties
| Property | Value (Imperial) | Value (Metric) |
| Yield Strength | 80,000 - 95,000 psi | 552 - 655 MPa |
| Tensile Strength (Min) | 95,000 psi | 655 MPa |
| Max Hardness | 23 HRC | 241 HBW |
| Elongation | Based on cross-sectional area | Based on cross-sectional area |
API 5CT L80 BTC oil well casing Dimensions and Tolerances
Common BTC Casing Sizes
| Outside Diameter (OD) | Wall Thickness (WT) | Nominal Weight | Drift Diameter |
| 5-1/2" | 0.361" (9.17 mm) | 20 lb/ft | 4.563" (115.90 mm) |
| 7" | 0.417" (10.59 mm) | 29 lb/ft | 6.093" (154.76 mm) |
| 9-5/8" | 0.472" (11.99 mm) | 47 lb/ft | 8.681" (220.50 mm) |
Standard Tolerances
| Parameter | Tolerance Range |
| Outside Diameter (OD) | OD < 4-1/2": ±0.031"; OD ≥ 4-1/2": -0.5% to +1% |
| Wall Thickness (WT) | -12.5% (Maximum is governed by weight) |
| Weight | Single joint: -3.5% to +6.5%; Carload: -1.75% |
| Straightness | < 0.2% of total length (deviation < 3.2mm in last 1.5m) |
| Length | Range 1 (4.88-7.62m), Range 2 (7.62-10.36m), Range 3 (>10.36m) |
API 5CT L80 BTC casing pipe Manufacturing Types
L80 casing is strictly regulated regarding its production process:
Process: Must be manufactured via the Seamless (SMLS) process. Welded (ERW) L80 is not permitted under API 5CT.
Threading: BTC threads must be machined and inspected according to API Spec 5B.
API 5CT L80 BTC oilfield casing pipe Heat Treatment Methods
Proper heat treatment is mandatory to achieve the required mechanical properties and hardness limits.
Quenching & Tempering (Q+T): The pipe is heated to an austenitizing temperature, rapidly cooled (quenched in water or oil), and then reheated to a tempering temperature (minimum 565°C / 1050°F).
Purpose: To ensure a uniform martensitic structure and to keep the hardness below the critical threshold for Sulfide Stress Cracking (SSC).
Reference Inspection of API 5CT L80 BTC Casing
Standard inspections include:
Visual Inspection: Checking for surface defects, straightness, and marking accuracy.
Dimensional Check: Measuring Outside Diameter (OD), Wall Thickness (WT), and Length.
Thread Inspection (API 5B): Verification of thread lead, taper, height, and standoff.
Drift Test: Passing a standard drift mandrel through the pipe to ensure no internal obstructions.
Hydrostatic Test: Every joint is pressurized to a specified level (usually held for 5 seconds) to ensure no leakage.
Non-Destructive Testing (NDT)
For L80, the pipe must undergo rigorous NDT to detect internal or surface flaws:
EMI (Electromagnetic Inspection): Detects longitudinal and transverse flaws.
UT (Ultrasonic Testing): Full pipe body wall thickness measurement and internal flaw detection.
MPI (Magnetic Particle Inspection): Specifically used for pipe ends and thread areas to detect surface cracks.
Standard: Typically required to meet API 5CT L2 acceptance level (imperfections > 5% of wall thickness are rejected).
Production Process Of Casing Pipe
GNEE API 5CT L80 BTC Casing process line
GNEE API 5CT L80 BTC Casing test equipments
GNEE API 5CT L80 BTC OCTG Casing certificate
FAQ
What is the difference between L80-1, L80 9Cr, and L80 13Cr in API 5CT?
While all three grades belong to the API 5CT L80 family and share the same mechanical strength (Yield: 80–95 ksi), the primary differences lie in their chemical composition and corrosion resistance.
| Feature | L80-1 | L80 9Cr | L80 13Cr |
| Cr Content | None (or trace) | 8.00% – 10.00% | 12.00% – 14.00% |
| Main Target |
H2S (Sour Service) |
Moderate CO2 | High CO2 |
| Yield Strength | 80,000–95,000 psi | 80,000–95,000 psi | 80,000–95,000 psi |
| Max Hardness | 23 HRC | 23 HRC | 23 HRC |
What's the difference between tubing and casing?
In the simplest terms, Casing is the permanent "outer wall" of the well, while Tubing is the "inner pipe" through which the oil or gas actually flows to the surface.
| Feature | Casing | Tubing |
| Primary Goal | Protect the wellbore & environment | Transport oil/gas to surface |
| Placement | Outer layer | Inner layer (inside casing) |
| Cementing | Yes (Permanent) | No (Replaceable) |
| Diameter | Large (up to 20") | Small (usually ≤ 4-1/2") |
| Analogy | The walls of a house | The plumbing pipes in the house |
Is BTC a premium connection?
No. BTC (Buttress Thread Connection) is an API Standard Connection, not a "Premium" connection.
| Connection Type | Best Used For | Cost |
| BTC (API) | Standard oil wells, water injection wells, and low-pressure environments. | Lower |
| Premium | High-pressure gas wells, deepwater, horizontal drilling, and HPHT (High Pressure/High Temp) wells. | Higher |
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