Product Overview
The Flexible Joint is a high-flexibility torque-transmissible downhole accessory specially engineered for coiled tubing fishing, coiled tubing drilling and complex tortuous well trajectory intervention operations. It adopts an integrated dual-joint structure, assembled by two independent torque thru knuckle joints each supporting maximum 15° angular deviation.
The dual-knuckle stacked design delivers twice the deflection flexibility compared with single torque thru knuckle joints, significantly improving the overall bending performance of long downhole tool strings. This unique structural advantage allows the tool string to smoothly navigate sharp borehole bends, tight doglegs and narrow restricted sections in deviated, horizontal and highly tortuous wells, effectively reducing tool string friction, sticking risk and running failure probability.
Retaining the core torque transmission capability of torque thru knuckle joints, this flexible joint can stably transfer rotary torque generated by downhole drilling motors to lower fishing or drilling working tools, while protecting vulnerable downhole equipment from torque impact damage. All standard flexible joint models adopt STD standard carbon steel as base material, with complete outer diameter specifications ranging from 1-11/16" to 2-7/8", equipped with three mainstream oilfield connection thread standards: 1" AMMT, 1-1/2" AMMT and 2-3/8" PAC. The integral sealed dual-joint structure minimizes internal vulnerable wearing components, ensuring stable long-term downhole torque-bearing service performance and low daily maintenance requirements.
Complete Technical Specification Table
| PN Part Number | Outer Diameter OD | Internal Through Bore ID | Overall Make-Up Length | Working Condition Grade | Connection Thread |
|---|---|---|---|---|---|
| L4021690120 | 1-11/16" | 0.33" | 12" | STD Standard Carbon Steel | 1" AMMT |
| L4021750120 | 1-3/4" | 0.33" | 12" | STD Standard Carbon Steel | 1" AMMT |
| L4022125120 | 2-1/8" | 0.5" | 13.4" | STD Standard Carbon Steel | 1-1/2" AMMT |
| L4022875120 | 2-7/8" | 0.94" | 14" | STD Standard Carbon Steel | 2-3/8" PAC |
Core Features & Advantages
Dual Independent Torque Thru Knuckle Joint Design This flexible joint integrates two separate torque transmissible knuckle joints into one integral unit, each individual knuckle joint supports maximum 15° free angular deflection. The stacked dual-joint layout provides compound multi-directional bending flexibility far superior to single knuckle joints, perfectly adapting irregular, sharply curved wellbore trajectories in complex deviated and horizontal wells.
Built-in Torque Thru Transmission Capability Different from conventional non-torque flexible knuckle joints, both internal knuckle joints adopt special internal torque transmission structures. The complete flexible joint unit can continuously and stably transfer rotary torque from upper coiled tubing string to lower drilling motors, fishing tools and other torque-bearing working equipment, avoiding torque accumulation, torsion deformation and structural damage of downhole tools during drilling and fishing operations.
Ultra-High Tool String Flexibility for Sharp Bend & Restriction Passage The compound dual-15° deflection design drastically enhances the overall bending flexibility of long downhole tool strings. When running through sharp borehole doglegs, tight bends and narrow restricted sections, the dual-knuckle flexible joint actively adjusts the tool string running angle in multiple directions, greatly reducing rigid collision and friction resistance between the tool string and irregular borehole walls, significantly lowering stuck pipe risk and improving operation success rate for complex trajectory wells.
Full-Size Standard Thread Matching System The complete flexible joint product line is configured with standardized oilfield connection threads corresponding to different outer diameter sizes. Small OD models match 1" AMMT thread, medium OD models adopt 1-1/2" AMMT thread, and large-size models support 2-3/8" PAC thread. All thread sizes follow unified industry precision machining standards, enabling direct plug-and-play assembly with coiled tubing strings, weight bars, drilling motors, torque thru knuckle joints and fishing tool assemblies without secondary modification or extra adapter conversion.
Fully Sealed Integral Dual-Joint Structure, Stable Downhole Service Performance The internal torque transmission and deflection moving components of both built-in knuckle joints are wrapped by high-performance integrated sealing assemblies, effectively isolating downhole formation fluid, completion brine and solid sand debris from internal transmission parts. It avoids internal component corrosion, sand jamming, torque transmission failure and deflection jamming under long-term downhole torque-bearing working conditions, greatly extending the service cycle of the flexible joint and reducing on-site tool replacement frequency.
Low Maintenance & Simple On-Site Assembly Operation There are no fragile spring parts or easily worn sealing components inside the flexible joint main body. The overall forging structure is sturdy and impact-resistant, capable of enduring long-term downhole torque, compression and bending loads. On-site assembly only requires standard torque tightening of upper and lower connection threads, which greatly shortens tool string pre-assembly time before well operation. After finishing downhole service, only simple surface cleaning and appearance inspection are needed, cutting down after-sales maintenance labor cost and spare parts inventory pressure.
Application Scenarios
1. Conventional onshore and offshore oil & gas well coiled tubing fishing operations, including fallen tubing, perforating gun, downhole tool fish retrieval in complex sharply curved wellbores.
2. Coiled tubing drilling operations matched with downhole drilling motors, stably transferring rotary torque and protecting drilling motors and vulnerable downhole tools from torque impact damage while navigating tight borehole bends.
3. Long coiled tubing tool string assembly for deep, highly deviated, horizontal and tortuous trajectory well intervention jobs, the dual-knuckle design maximizes overall tool string flexibility to pass narrow restrictions and sharp doglegs.
4. Conventional low-sulfur oil and gas well maintenance, well plugging, well abandonment and secondary reservoir reconstruction torque-bearing intervention operations.
5. Matching assembly with weight bar, drilling motors, torque thru knuckle joints, fishing spears and hydraulic setting tools to form complete standardized high-flexibility torque-transmissible coiled tubing downhole tool combination.
6. Slim small-diameter coiled tubing fishing and drilling service jobs for slim hole and compact wellhead oilfield projects with narrow wellbore passageways.
Standard Delivery Package
Complete pre-assembled integral flexible joint unit with factory precision thread finishing and surface anti-rust protective treatment.
Hard plastic thread protective caps and anti-collision packaging accessories for safe transportation and long-term warehouse storage.
Factory full dimensional tolerance inspection report, base material chemical composition analysis report and mechanical property tensile & torque load test certificate.
Official product installation operation guide and multi-stage flexible tool string matching assembly manual for on-site torque-bearing construction reference.
Optional customized thread precision inspection report and third-party independent material certification for overseas oilfield fishing & drilling project bidding document requirements.
Quality Warranty & After-Sales Service
Warranty Coverage: 12 months after factory shipment or 500 times cumulative downhole tripping & torque transmission operation cycles, whichever condition comes first.
Strict full factory inspection: Every flexible joint passes dimensional tolerance detection, thread precision inspection, torque transmission performance test, dual-joint sealing performance test and surface defect visual inspection before leaving factory.
Free professional global technical support: Tool string matching consultation, multi-stage flexible joint quantity selection guidance and working condition material grade recommendation for all overseas and domestic clients.
Long-term stable spare parts supply: Full complete size series inventory supports bulk wholesale order and fast global sea & air delivery arrangement.
Customized engineering service: Support non-standard outer diameter, internal through bore size, assembly length, special connection thread and H₂S anti-sulfide corrosion alloy material flexible joint customization according to client technical drawings, field well parameters and actual downhole torque-bearing working conditions.
FAQ
Q1: What is the core structural difference between Flexible Joint and single Torque Thru Knuckle Joint?
The single torque thru knuckle joint consists of only one 15° deflection torque-transmissible joint unit. The Flexible Joint is an integrated unit assembled by two independent torque thru knuckle joints, each with 15° angular deflection capability. The dual-knuckle stacked design provides compound multi-directional bending flexibility, which greatly exceeds the deflection performance of single knuckle joints, making it more suitable for complex wells with sharp borehole bends and narrow restrictions.
Q2: Does the Flexible Joint retain torque transmission capability?
Yes. Both built-in knuckle joints of the flexible joint adopt professional internal torque transmission structures. The entire flexible joint unit can continuously and stably transfer rotary torque generated by upper drilling motors and coiled tubing strings to lower fishing and drilling working tools, while avoiding torque accumulation and structural damage of downhole equipment during torque-bearing operations such as fishing and drilling.
Q3: What is the main advantage of using Flexible Joint in complex trajectory wells?
The core advantage is ultra-high compound flexibility. The two built-in 15° deflection knuckles can adjust the tool string running angle in multiple directions synchronously, effectively adapting sharply curved, irregular wellbore trajectories. It drastically reduces the rigid friction and collision between long tool strings and borehole walls, greatly lowering the risk of tool sticking and running failure when passing sharp doglegs and narrow restricted sections in deviated and horizontal wells.
Q4: What standard connection threads does the Flexible Joint support?
Our full-series flexible joints are equipped with three mainstream oilfield standard connection threads matched with different outer diameter sizes: 1" AMMT for small OD models, 1-1/2" AMMT for medium OD models, and 2-3/8" PAC for large OD models. All thread specifications follow unified industry precision machining standards, realizing direct matching with weight bar, drilling motor, torque thru knuckle joint, fishing tools, coiled tubing string and other downhole intervention tools without extra adapter conversion.
Q5: Do you accept customized non-standard Flexible Joint specifications and anti-sulfide material versions?
Yes, we provide full customized engineering solutions for global clients. We can manufacture non-standard outer diameter, internal through bore size, overall assembly length, special non-standard connection thread flexible joints strictly according to client technical drawings and field well parameters. Besides standard STD carbon steel grade, NACE MR0175 compliant H₂S sour service anti-sulfide corrosion alloy versions are available for high-hydrogen-sulfide corrosive downhole environments.
Get Custom Datasheet & Factory Quote
We are a professional OEM & ODM manufacturer specializing in full series oilfield coiled tubing well intervention tools, supplying high-performance dual-knuckle flexible joints, single torque thru knuckle joints, conventional sealed knuckle joints, solid weight bars, hydraulic setting tools, fishing tools, drilling motor matching accessories and complete sets of supporting downhole service tools for global onshore and offshore oil & gas field fishing and drilling projects. All our products adopt standardized forging and precision machining process with strict multi-stage factory torque load, dual-joint sealing and dimensional testing, featuring stable long-term downhole torque-bearing working performance and excellent cost performance ratio. Whether you need standard-size STD carbon steel dual-knuckle flexible joints, multi-stage flexible tool string matching solutions or customized H₂S sour service anti-corrosion versions with non-standard specifications, please feel free to contact our professional engineering team. We will provide targeted high-flexibility torque-transmissible tool string matching solutions, complete detailed technical datasheets and competitive factory bulk wholesale quotations within 24 working hours.
