API 5CT Casing and Tubing Coupling
Our mill manufactures premium, API 5CT-certified seamless casing and tubing couplings, custom-engineered for high-pressure oilfield connection strings and structural downhole stability. We guarantee strict thread profile conformity, high collapse resistance thresholds, verified dimensional concentricity, and premium anti-galling surface treatments under direct [2-Hour Rapid Quote] mill terms.
Terrified of thread stripping, downhole joint leaks, or expensive project delays while your critical drilling installation deadline closes in? Eliminate connection coupling failures and secure your mill-verified testing certificates immediately.
PRODUCT DETAILS
Premium API 5CT Coupling Three-Standard Cross Matrix
| American Standard (API 5CT / ASTM) | International Standard (ISO 11960) | Available Thread Profiles | Min Yield Strength (Rpa) | Min Tensile Strength (Rm) |
|---|---|---|---|---|
| API 5CT J55 / K55 | ISO L55 | STC / LTC / BC / Premium | 379 MPa | 517 MPa |
| API 5CT N80-1 / N80-Q | ISO N80 | EUE / NUE / Premium Joints | 552 MPa | 689 MPa |
| API 5CT L80 / P110 | ISO L80 / P110 | BTC / EUE / Gas-Tight Premium | 552 / 758 MPa | 655 / 862 MPa |
Technical QA/QC Verification
• 100% Traceable API Mill Certificates: Every batch is accompanied by comprehensive EN 10204 3.1 Mill Test Certificates (MTC) proving exact heat chemistry tracking, material hardness maps, hydrostatic burst test limits, and dimensional logs. Fully prepared for third-party inspection by SGS, BV, or Intertek.
• Financial Security Guarantee: We eliminate cross-border transaction risk completely by processing high-volume manufacturing export supply agreements through 100% Irrevocable Letters of Credit (L/C) at sight.
Anti-Rust Packaging & Ocean Logistics
• Industrial Reinforced Crate Boxing: Finished couplings are securely nested inside heavy-duty steel-banded wooden crates or industrial metal boxes lined with waterproof protective cushioning to prevent component collisions and surface damage during ocean transit.
• Extended Port Demurrage Allocations: Our logistics coordinators secure 14 to 21 days of complimentary container demurrage at your destination terminal to shield local logistics workflows and customs clearance steps from storage surcharges.
About Tubing coupling
Normally tubing coupling OD maximum is 4 1/2”, as the tubing pipe is applied for the drilling activities (Inside the tubing is the sucker rod to drill/pump the oil), couplings type is more various and rigorous than casing, mostly used is thicken type upset coupling (Internal upset and external upset), for short is EUE coupling, it is the most favorable in tubing connections. Tubing with EU end (EUE) coupling connection also called UPTBG. Because of the end of the tubing is thickened (upset), the connecting stress is better than buttress coupling.
Buttress coupling another type used for tubing connections, it has the same thickness of the pipe body, called NU end (NUE)tubing or TBG.
Features
The oil tubing coupling can solve the problem of fatigue fracture in the existing coupling due to stress concentration. Oil tubing end is connected to the inside wall of the coupling in a tapered thread. The coupling body end and oil tubing are connected with same thread pitch flat thread. The coupling is not easy to produce fatigue fracture, and has good connection effect. It can prevent the accident of oil well pipe string break effectively.
About Casing coupling
Casing coupling is for the dimensions more than 4 1/2 inch. Differently than tubing coupling is, casing coupling normally does not need to be thickened (Non-upset), which means no upset casing coupling, so it has following types:
• BTC: Buttress coupling
• LTC: Long buttress coupling
• STC: Short buttress coupling
All three types has same thickness of the casing pipe body, just have different lengths.
The oil casing coupling is a necessary piece used to connect the two casing. The coupling manufacturing method is the same as seamless pipe. The steel pipe ends with internal thread to connect with the upper and lower casing. In order to ensure the joint tightness, the precision of screw thread is strictly required.
Seamless and ERW Casing
| Specification | API 5CT |
| Grades | K55, N80, L80, C95, P110, Chrome, J55(Modified), J55 (API), PS80 |
| Special Grades | For sour services and for deep well with high collapse properties |
| Dimensions | OD 4″ – 26″ WT – 0.2 – 0.5″ |
| Length range | 1, 2 or 3 |
| Thread connections | API (STC and LTC), BTC, extreme line, etc. |
Seamless and ERW Tubing
| Specification | API 5CT |
| Grades | J55 (API) J55(Modified), N80, L80, L80 13Cr, P110, Q125, H40 (API) |
| Thread connections | API 5B – Last Edition or Premium, EUE, NUE, special seal, metal-to-metal seal and VAGT |
Specification
Casing Couplings Short Thread Specifications:
Casing Couplings – Short Thread
| Casing Couplings Short Thread | Casing Size OD (inches) | Coupling Size OD (inches) | Length (inches) | Weight per Coupling (lbs) | Palletized Carton Quantity |
|---|---|---|---|---|---|
 | 4-1/2 | 5.000 | 6.250 | 8.05 | 343 |
Packing and shipping
Our company has passed ISO9001 quality management system certification, Our Mill product with CE/EN10204 / ASTM/Classification society certificate/CASO/BIS etc certificate.All the customers give good appreciation to our products.We are glad to be your good partner.
Application Areas
Steel is widely used in steel structure workshops, bridge frames, main structures of high-rise buildings, and infrastructure construction (such as highways, oil and gas pipelines). Its high strength properties ensure load-bearing stability and seismic performance. In ship manufacturing, steel is used to build hull structures, decks, and internal components. Hot-rolled coils rely on their load-bearing capacity to adapt to harsh environments.
Factory workshop
With a commitment to excellence, innovation, and sustainability, the company has established itself as a trusted partner in the international steel industry.After nearly two decades of relentless endeavour, our client base now spans over 110 countries and regions across Europe, the Middle East, South America, and Southeast Asia.
Free OCTG Connection Blueprint Audit & Joint Thread Selection Layout Optimization Report
Submitting technical connection layouts for downhole casing strings, high-pressure tubing wells, or complex oilfield infrastructure assemblies? Provide your required outer diameters, wall thicknesses, steel grades, precise thread specifications (EUE, NUE, STC, LTC, BTC, or Premium), or raw Bill of Materials (BOM) schematics below. Our engineering team will quickly run a compatibility analysis to optimize connection integrity and protect your total production margins.
