EUE Oil Tubing (External Upset End Tubing) is the industry-standard pipe used to transport oil and gas from the producing formation to the surface. It is defined by its thickened ends, which are designed to make the connection (the joint) as strong as or stronger than the main body of the pipe.
The "External Upset" (The Forging Process)
In standard pipes, cutting threads into the metal makes the wall thinner and creates a weak point. To prevent this, EUE tubing undergoes a forging process called upsetting:
The ends of the pipe are heated and compressed to make the walls thicker on the outside.
The threads are then cut into this thickened portion.
Result: The "critical area" under the threads has more metal, ensuring the joint can handle the massive weight of a miles-long tubing string without snapping.
EUE Tubing Dimensional
| Nominal OD (in) | Weight (lb/ft) | Pipe OD (mm) | Wall Thickness (mm) | ID (mm) | Drift Dia. (mm) | Upset OD (mm) | Coupling OD (mm) | Coupling Length (mm) |
| 1.900 | 2.75 | 48.26 | 3.68 | 40.89 | 39.30 | 52.39 | 63.50 | 95.25 |
| 2-3/8 | 4.60 | 60.33 | 4.83 | 50.67 | 48.29 | 65.88 | 77.80 | 123.83 |
| 2-7/8 | 6.40 | 73.03 | 5.51 | 62.01 | 59.61 | 78.58 | 93.17 | 133.35 |
| 3-1/2 | 9.20 | 88.90 | 6.45 | 76.00 | 72.82 | 95.25 | 114.30 | 142.88 |
| 4 | 11.00 | 101.60 | 6.65 | 88.30 | 85.12 | 107.95 | 127.00 | 152.40 |
| 4-1/2 | 12.60 | 114.30 | 6.88 | 100.54 | 97.36 | 120.65 | 141.30 | 155.58 |
In Stock & Ready to Ship: 2-3/8" & 2-7/8" EUE Tubing. Check Real-Time Availability Now.
EUE Thread Technical Specifications
| Parameter | Specification | Description |
| Thread Type | API 8-Round (8rd) | Rounded crests and roots to reduce stress concentration |
| Threads Per Inch (TPI) | 8 TPI | Standard for 2-3/8" and above (1.9" uses 10 TPI) |
| Taper | 1:16 (0.0625 mm/mm) | Equivalent to 3/4" per foot (3/4" TPF) |
| Thread Height | 1.810 mm (0.0712 in) | Theoretical depth of the thread profile |
| Sealing Method | Interference Fit + Dope | Seal is formed by flank-to-flank contact & thread compound |
Common Steel Grades & Mechanical Properties
Material selection is based on well depth, pressure, and corrosive elements (H2S/CO2).
| Steel Grade | Yield Strength (psi) | Tensile Strength (psi) | Color Coding | Application Environment |
| J55 | 55,000 - 80,000 | ≥ 75,000 | One Bright Green Band | Standard shallow to medium wells |
| N80-1/Q | 80,000 - 110,000 | ≥ 100,000 | One Red Band | Deep wells with higher load requirements |
| L80-1 | 80,000 - 95,000 | ≥ 95,000 | Red + Brown Bands | Sour Service (H2S resistant) |
| P110 | 110,000 - 140,000 | ≥ 125,000 | One White Band | Ultra-deep, high-pressure wells |
Engineering Terminology
External Upset (EU): Refers to the forging process that increases the wall thickness at the pipe ends. This ensures the threaded connection is as strong as, or stronger than, the pipe body.
Drift Diameter: The most critical parameter for downhole operations. It represents the "guaranteed" clearance for tools (pumps, packers) to pass through the tubing.
Makeup Loss: The reduction in total length of a tubing joint once it is fully screwed into the coupling. For 2-7/8" EUE, this is approximately 2.35 inches (59.69 mm).
Makeup Torque: The rotational force required to tighten the connection. Operators must follow API Optimum Torque values to prevent coupling "hooping" (expansion) or seal failure.
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FAQ
What are External Upset (EUE) Threads?
External Upset End (EUE) threads are heavy-duty connections used primarily on oil and gas production tubing.
Here is the simplest way to understand them:
The "Upset": Before the threads are cut, the ends of the pipe are made thicker through a forging process.
The Purpose: Usually, cutting threads into a pipe makes the metal thinner and weaker at the joint. By thickening (upsetting) the ends first, the joint becomes as strong as the rest of the pipe body.
The Design: They typically feature 8 round threads per inch (8rd). The rounded shape helps prevent damage during assembly and reduces stress.
The Benefit: EUE threads can support the massive weight of a tubing string hanging miles deep in a well and provide a reliable seal under high pressure.
What is the difference between Nue and EUE tubing?
The main difference lies in the thickness of the pipe ends and the strength of the connection.
Differences Comparison Table (EUE vs. NUE)
| Feature | EUE (External Upset End) | NUE (Non-Upset End) |
| Pipe End Profile | Thickened/Forged (Ends are thicker than the body) | Standard/Straight (Ends have the same thickness as the body) |
| Joint Strength | High (Joint Efficiency ≥100% of pipe body) | Moderate (Joint is the weak point, ~60-80% efficiency) |
| Threads Per Inch (TPI) | 8 TPI (8rd) | 10 TPI (10rd) |
| API Code | EU | NU |
| Sealing Performance | Excellent; suitable for high-pressure environments | Standard; suitable for low/medium pressure |
| Primary Application | Deep wells, High-pressure wells, Standard Production Tubing | Shallow wells, Low-load wells, Utility/Surface lines |
What is the difference between external upset and non upset?
The main difference is whether the ends of the pipe are thickened (forged) before the threads are cut.
1. External Upset (EUE)
The Shape: The ends of the pipe are forged to be thicker on the outside than the rest of the pipe body.
The Strength: Because the metal is thicker, the connection is stronger than the pipe itself. It can handle heavy loads and high pressure without snapping at the threads.
The Thread: Usually has 8 threads per inch (8rd).
2. Non-Upset (NUE)
The Shape: The pipe is straight. The ends have the same thickness as the rest of the pipe.
The Strength: Cutting threads removes metal from the pipe wall, making the connection the weakest point (about 60-80% of the pipe's strength).
The Thread: Usually has 10 threads per inch (10rd).
