Non Upset or NU Connection

Understanding Non-Upset (NU) Connections in Oil & Gas

In the world of oil and gas, precise and reliable connections are crucial for safe and efficient operations. One common type of connection, the Non-Upset (NU) connection, is specifically designed for specific applications where its unique characteristics are advantageous.

What is a Non-Upset (NU) Connection?

An NU connection, sometimes referred to as a plain end connection, is a pipe connection that maintains a consistent internal diameter (I.D.) and external diameter (O.D.) throughout the connection. Unlike other types of connections like External Upset (EU) or Internal Upset (IU) connections, the NU connection does not have any thickened areas or "upsets" at the connection point. This results in thin connection walls that are comparatively weaker than EU or IU connections.

Key Characteristics of NU Connections:

• Consistent I.D. and O.D.: This ensures smooth fluid flow without any restrictions or turbulence caused by variations in diameter.
• Thin Connection Walls: The thinner walls make the connection lighter and less expensive to manufacture.
• Lower Strength: The reduced wall thickness results in lower strength compared to EU or IU connections, limiting its application to specific situations.

Applications of NU Connections:

Despite their lower strength, NU connections find their niche in various applications within the oil and gas industry:

• Flush Joint Liners: These liners are used to reinforce existing pipelines or to repair damaged sections. The consistent diameter of the NU connection ensures a smooth transition between the liner and the original pipe.
• Wash Pipes: These pipes are used for cleaning out wells or pipelines. The smooth interior and thin walls of the NU connection allow for efficient cleaning with minimal resistance.
• Specific Applications: NU connections can also be used in situations where weight and cost are critical factors, and where the pressure and stress conditions are low enough to not compromise the integrity of the thinner connection.

Advantages of NU Connections:

• Cost-Effectiveness: The thinner walls and simplified design result in lower manufacturing costs.
• Reduced Weight: The lightweight design is beneficial for transportation and installation.
• Smooth Flow: The consistent diameter ensures smooth fluid flow, reducing friction and pressure loss.

Disadvantages of NU Connections:

• Lower Strength: The thinner walls result in lower strength compared to other connection types. This limits the use of NU connections to applications with lower pressure and stress requirements.
• Limited Applications: Their lower strength restricts their use to specific applications where other types of connections might be more suitable.

Conclusion:

NU connections offer a unique combination of features that make them ideal for specific applications in the oil and gas industry. Their consistent diameter, thin walls, and lower strength characteristics make them suitable for flush joint liners, wash pipes, and other situations where cost and weight are critical factors. By understanding their advantages and limitations, engineers and operators can choose the most appropriate connection type for their specific needs, ensuring safe and efficient operations.