3-1/2" NU BOX X 2-7/8" EU BOX 200MM X-over N80 Grade
Products informtion:
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3-1/2" NU BOX X 2-7/8" EU BOX 200MM X-over N80 Grade is a crossover sub (also called a size adapter or thread converter) used in oilfield tubular systems. It is primarily employed to connect tubing or casing strings with different thread specifications and dimensions, enabling transitional connections within a well string assembly.
The detailed parameter breakdown is as follows:
3-1/2" NU BOX
- One end is a 3.5-inch Non-Upset (NU) female coupling (BOX), designed to mate with a 3-1/2" NU male pin (PIN) tubular body. This configuration is commonly found in mid-string tubing sections or for attaching lifting subs and other accessories.
2-7/8" EU BOX
- The other end is a 2.875-inch External Upset (EU) female coupling (BOX), which must be used with a 2-7/8" EU PIN.
- Note: A dual-female (BOX-BOX) design is atypical for standard crossover subs, which normally follow a "male-female" (PIN-BOX) configuration to enable in-line string continuity. This arrangement may be intended for specialized tooling or test fixtures; it is recommended to verify against field drawings whether one end should be a PIN.
200MM Length
- The sub body length is approximately 200 millimeters, classifying it as a short-length crossover sub, suitable for compact downhole tool assemblies where space is constrained.
N80 Material Grade (Grade)
- The material complies with the N80 steel grade specified in API 5CT, offering high tensile strength (minimum yield strength 80,000 psi) and good corrosion resistance, making it suitable for medium-depth and high-pressure oil and gas well applications.
- N80-grade material is widely used in tubing, casing, and crossover connections, providing reliable mechanical performance and sealing integrity.
X-over Function
- As a crossover sub, its core function is to enable transitions between different sizes and thread types. It is extensively used in drill string configurations, completion strings, or workover operations to ensure secure and reliable connections between dissimilar components.
N80-grade crossover subs are commonly used connecting components in petroleum drilling and production operations, widely employed for dimensional and thread conversion between tubing and casing. The following is a Common Specification Reference Table for N80-Grade Crossover Subs compiled based on industry standards (API 5CT, API 5B) and typical engineering requirements, covering mainstream sizes, thread types, connection forms, and typical application scenarios to facilitate rapid on-site selection and matching.
N80-Grade Crossover Sub Common Specification Reference Table
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表格
| No. | Crossover Sub Model (X-over) | One End Specification | Other End Specification | Common Length | Thread Standard | Typical Application Scenario |
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| 1 | 3-1/2" NU BOX × 2-7/8" EU PIN | 3.5" NU Female | 2.875" EU Male | 200mm / 300mm | API 5CT / 5B | Tubing string transition connection, workover tool access |
| 2 | 4-1/2" LTC BOX × 3-1/2" NU PIN | 4.5" LTC Female | 3.5" NU Male | 300mm | API 5CT | Casing-to-tubing connection, completion string assembly |
| 3 | 2-7/8" EU BOX × 2-3/8" NU PIN | 2.875" EU Female | 2.375" NU Male | 150mm / 200mm | API 5CT | Small-diameter tubing extension or pumping tool connection |
| 4 | 3-1/2" EU BOX × 2-7/8" EU PIN | 3.5" EU Female | 2.875" EU Male | 250mm | API 5CT | Transition between different-diameter EU tubing |
| 5 | 4-1/2" BTC BOX × 3-1/2" EU PIN | 4.5" BTC Female | 3.5" EU Male | 300mm | API 5CT | High-pressure well casing-to-tubing conversion connection |
| 6 | 2-3/8" NU BOX × 1.9" EU PIN | 2.375" NU Female | 1.9" EU Male | 150mm | API 5CT | Electrical submersible pump (ESP) string or coiled tubing connection |
| 7 | 3-1/2" VAM TOP BOX × 2-7/8" EU PIN | 3.5" VAM Female | 2.875" EU Male | 200mm | VAM Series | High-seal-requirement well conditions, commonly used in international projects |
Notes:
- N80 Steel Grade: Minimum yield strength 80,000 psi, suitable for medium-depth wells (≤3500m), with good tensile and collapse resistance.
- Thread Types:
- NU (Non-Upset): Plain-end thread, commonly used for lightly loaded tubing.
- EU (External Upset): External upset thread, enhances connection strength.
- LTC (Long Thread Coupling): Long-round thread, used for casing.
- STC (Short Thread Coupling): Short-round thread, used for casing.
- BTC (Buttress Thread): Buttress thread, good sealing performance, suitable for high-pressure environments.
- VAM: High-gas-tight thread, often used in high-end or export projects.
- Connection Orientation: Standard crossover subs follow a "one male (PIN), one female (BOX)" configuration to achieve in-line string connection. If both ends are BOX, it requires intermediate subs or special tools for use; the design intent should be carefully verified.