4” XT39 Drill Pipe Specs

A drill pipe is a steel pipe with threads at one end. The 4” XT39 drill pipe is a high-strength oil drill pipe conforming to API 5DP standards. Made of S-135 steel with an internally thickened (IU) construction, it is suitable for medium-deep wells and high-torque drilling conditions.

This drill pipe exhibits excellent performance in tensile strength, internal pressure resistance, collapse resistance, and connection torque safety margin, and is widely used in onshore oil and gas wells and conventional directional drilling operations.

Advantages of the 4” XT39 Drill Pipe

1. High-strength S-135 pipe body, suitable for high-load drilling.

2. XT39 high-performance tool joint with strong torsional resistance.

3. Optimized inner diameter design for improved mud circulation efficiency.

4. Meets API Premium testing standards.

4” XT39 Drill Pipe Body Specifications

IU internal thickening structure: Reduces outer diameter changes while ensuring strength, improving wellbore adaptability.

Range 2 length: Suitable for most standard drilling conditions, balancing transportation and construction efficiency.

XT39 Tool Joint Specifications

The XT39 connection is a medium-to-high strength drill pipe connection type that provides stable torsional resistance while maintaining a small outer diameter, making it ideal for use with S-135 steel grade 4-inch drill pipes.

4” XT39 Drill Pipe Body Performance

Burst pressure is calculated based on API standard 87.5% RBW; axial load and bending effects are not considered.

XT39 Connection Makeup Torque Specifications

FF = 1.15 Based on copper-based thread compound;

The increased coefficient of friction improves the torsional resistance of the tool joint by approximately 15%;

It is recommended that the drilling torque be ≤ 80% of the top thread torque to ensure a safe connection.

XT39 Drill Pipe vs NC38 Drill Pipe

XT39 and NC38 are both commonly used in 4-inch drill pipes and are therefore frequently compared in actual projects. However, it is important to clarify that XT39 is not an API standard connector, while NC38 is a standard NC series connector in the API 5DP system. This determines the fundamental difference in their versatility and interchangeability.

1. Size Differences

XT39 is very similar to NC38 in terms of outer diameter, inner diameter, and torque rating.

In 4" S-135 drill pipe applications, both XT39 and NC38 are typically in the same torque rating range, and are therefore often described in engineering as "functional equivalent."

2. Connection Structure Differences

In terms of connection structure, XT39 and NC38 use completely different thread systems.

XT39 uses a dedicated thread for the XT series, while NC38 uses the API-specified NC thread, with different thread profiles, tapers, and pitches.

Therefore, XT39 connectors cannot be directly screwed onto NC38 connectors. Forcing such a connection can easily lead to seizing, abnormal thread wear, and even connection failure or breakage under high torque conditions.

If both XT39 and NC38 are present in the drilling system, the only safe and compliant solution is to use an XT39 × NC38 crossover sub. This crossover sub allows for a transition between different connector systems while ensuring connection strength and torque safety.

3. Application Differences

From an application perspective, NC38 is more suitable for API standards. Projects requiring standard-mandated specifications, such as drilling rigs operated by international oil companies (IOCs), national oil companies (NOCs), or multiple suppliers, typically demand a high degree of standardization and global compatibility.

XT39, on the other hand, is more often used for customized projects without API mandates or in situations where existing XT series drilling systems are available. While meeting engineering requirements, it often offers greater flexibility in cost control and delivery time.

 4” XT39 Drill Pipe Applications

1. Medium-deep oil and gas drilling;

2. Conventional directional drilling;

3. High-speed + medium-high torque conditions;

4. Onshore oilfield drilling projects.

FAQ

1. What is the equivalent connection for the XT39 connection?

There is no 100% officially equivalent API standard connector for the XT39.

In practical applications, the XT39 is generally considered closest to the NC38 (API NC38) in size and performance, and therefore is considered functionally equivalent in some projects, but they are not directly interchangeable.

2. Does XT39 comply with API 5DP?

Pipe Body: Fully compliant with API 5DP (e.g., S-135); 

Tool Joint: XT39 itself is not an API NC series connector;

However, its mechanical performance calculation methods and testing standards can refer to API 5DP / API RP 7G.

Read more: Drill Pipe Weight Chart and Calculation or Is Drill Pipe Weldable?