API 5CT Tubing and Casing Couplings are essential OCTG products widely used in oilfield drilling and oil & gas applications. We supply high-quality API tubing couplings and casing couplings including EUE, NUE, BTC, LTC and STC types in steel grades such as J55, K55, N80, L80 and P110. Our API couplings are manufactured with precision thread machining, excellent sealing performance and strict quality inspection to ensure reliable performance in demanding oilfield environments. As a professional OCTG coupling supplier, we provide competitive pricing, fast delivery and customized solutions for global oil and gas projects.

1. API Tubing Coupling:

Specification  
Size (Pipe OD) (in) :1.900, 2-3/8, 2-7/8, 3-1/2, 4, 4-1/2
Upset:Non Upset;External Upset
Grade:J-55, C-75, L-80, N-80, C-95, P-110
Option:Electro-zinc plated;Phosphorised

2. API Casing Coupling:
Specification  
Size (Pipe OD) (in):4-1/2, 5, 5-1/2, 6-5/8, 7, 7-5/8, 8-5/8, 9-5/8, 10-3/4, 11-3/4, 13-3/8, 16, 18-5/8, 20
Threading:Short Round-Thread Casing (STC);Long Round-Thread Casing (LC);Buttress Thread Casing (BC)
Grade:H-40, J-55, K-55, C-75, L-80, N-80, C-95, AS-95, P-110, L80-13CR

Coupling standard

API 5B, Specification for Threading, Gauging and Thread Inspection of Casing, Tubing, and Line Pipe Threads.This Specification covers dimensions, tolerances and marking requirements for API threads and the gauges that control the acceptance criteria for the threads. Thread element gauges, instruments and requirements for the inspection of threads for line pipe, round thread casing, and buttress casing connections are included.  

API Spec 5CT, Specification for Casing and Tubing, Eighth Edition, Petroleum and natural gas industries-Steel pipes for use as casing or tubing for wells.This Standard specifies the technical delivery conditions for steel pipes (casing, tubing and pup joints), coupling stock, coupling material and accessory material and establishes requirements for three Product Specification Levels (PSL-1, PSL-2, PSL-3).

Application: 

API 5CT Tubing and Casing Couplings are widely used in oilfield drilling, oil well completion and OCTG applications. They are designed for connecting tubing pipes and casing pipes in oil and gas extraction systems, providing secure thread connection and reliable sealing performance under high pressure and harsh operating conditions. These couplings are commonly used in onshore and offshore drilling projects, petroleum transportation systems and oilfield production equipment.

Structure:The casing end is connected with the inner wall of the coupling by tapered thread, and the end of the coupling body is connected with the oil pipe by the same thread and the same pitch flat thread. The utility model has the characteristics of relieving the stress concentration at the root of the external thread of the single taper thread connecting sleeve, not easy to produce fatigue fracture, and the connection effect is good.

The thread type of casing couplngs main include: Long Round-thread Casing Coupling(LC), Short Round-thread Casing coupling(SC), Buttress Thread Casing Coupling(BC)

API 5CT Short Round-thread Casing Couplings (STC Couplings) are widely used in OCTG, oilfield drilling and well completion applications. Our API casing couplings are available in J55, K55, N80, L80 and P110 steel grades with precision thread machining and reliable sealing performance. These Short Round-thread Casing Couplings are designed for secure casing pipe connection in onshore and offshore oil and gas projects, providing high strength, corrosion resistance and long service life for demanding drilling environments.

Casing Couplings Short Thread Specifications:

API 5CT Long Round-thread Casing Couplings are designed for connecting casing pipes in deep well drilling and high-pressure oilfield applications. Compared with Short Round-thread Couplings, LTC couplings provide longer thread engagement and improved connection strength for demanding OCTG operations. Available in J55, K55, N80, L80 and P110 grades, our API casing couplings feature accurate thread tolerance, strong load capacity and reliable sealing performance for oil and gas drilling, petroleum transportation and well completion systems.

Casing Couplings Long Thread Specifications:

API 5CT Buttress Thread Casing Couplings (BTC Couplings) are specially designed for high-torque and high-load oilfield drilling applications. Featuring a buttress thread profile with superior axial load capacity and enhanced sealing performance, BTC casing couplings are ideal for deep wells, heavy-duty casing strings and demanding OCTG operations. Manufactured in J55, K55, N80, L80 and P110 steel grades, our API BTC couplings provide excellent connection strength, wear resistance and reliable performance for onshore and offshore oil and gas projects.

Casing Coupling - Buttress Thread

API 5CT EUE and NUE Tubing connections are developed for different oilfield operating conditions and drilling requirements. External Upset End (EUE) tubing is manufactured with reinforced pipe ends to increase tensile strength and improve connection reliability under heavy load and high-pressure drilling environments. Non Upset End (NUE) tubing provides a more economical and lightweight connection option with larger internal diameter, making it suitable for conventional oil well production and standard OCTG applications. Available in J55, K55, N80, L80 and P110 grades, our API tubing products ensure accurate thread performance, stable operation and long service life in oil and gas projects.

Tubing Couplings - External Upset End (EUE):

Tubing Couplings - Non Upset End (NUE)

How to Identification Coupling Pipe Grade  By Paint Color?

MONO Group is one of Coupling Manufacturer, Supplier, Wholesaler,Exporter from China, We supply high-quality oilfield casing&Tubing, Sucker rod, Sucker rod pump and and custom parts in accordance with API 11AX,API 5CT, API 11B and other international standards. For inquiries or to request a quote, please freely contact us at info@monokj.com.