API 5CT OCTG Casing Pipe Size Chart and Specifications

　　The API 5CT OCTG casing size chart is an important reference document for oil and gas drilling operations. Casing is installed in oil and gas wells to stabilize the wellbore, isolate formations, and prevent wellbore collapse under high pressure and high temperature conditions. Selecting the appropriate casing size ensures the integrity, safety, and long-term performance of the oil well.

　　OCTG pipes mainly include three categories:

　　1.Casing Pipe – Stabilizes the wellbore and prevents collapse

　　2.Tubing Pipe – Transports oil and gas from the reservoir to the surface

　　3.Drill Pipe – Transmits drilling torque and drilling fluid

　　All OCTG products are typically manufactured according to API 5CT (casing & tubing) and API 5DP (drill pipe).

　　API Standards for OCTG Casing Pipes

　　StandardDescription

　　API 5CTSpecification for casing and tubing

　　API 5BThreading, gauging, and inspection

　　ISO 11960International equivalent of API 5CT

　　OCTG Casing Pipe Size Chart (API 5CT)

　　Below is a standard API 5CT OCTG casing pipe size chart, commonly used in oil and gas wells worldwide.

　　Steel Grades and Thread Types

　　According to API SPEC 5CT, casing steel grades include H40, J55, K55, N80, L80, C90, T95, P110, Q125, V150, etc. . The number in the grade name typically indicates the minimum yield strength in units of 1,000 psi (e.g., N80 has a minimum yield strength of 80,000 psi or approximately 552 MPa) . Different grades are selected based on well depth and conditions: J55 for shallow, low-pressure wells; N80 series for medium-depth wells; P110, V150 for ultra-deep wells and complex geological condition.

　　Thread Types

　　Short Thread Casing (STC): Suitable for general well conditions .

　　Long Thread Casing (LTC): Suitable for deeper well conditions .

　　Buttress Thread Casing (BTC): Suitable for deep and ultra-deep wells .

　　Premium Connections: Non-API threaded connections developed by manufacturers with special sealing, connection, and other performance characteristics, such as VAM, TM, FOX, etc. These are used when API threads are inadequate, especially in high-pressure gas fields or with high-grade pipes (e.g., Q125 and above)

　　Typical Applications of OCTG Casing Pipes

　　Shengtian Group is a supplier of API 5L line pipes & OCTG casing pipes, covering a wide range of sizes, wall thicknesses, and end treatments, designed to meet the stringent requirements of oil, gas, and industrial pipeline systems.Email : pipe@stpipefitting.cn