• TurboTorque™ (TT™) Connection

    Description

    Grant Prideco's industry-leading eXtreme™ Torque (XT™) connections have been meeting the requirements of the most challenging drilling applications for years. These patented connections have proven especially well suited for extended reach, horizontal, deep water, HPHT (High Temperature, High Temperature) and ultra-deep environments. Now, Grant Prideco introduces a new line of connections intended to drill deeper and further, faster than ever before.

    TurboTorque™ connections are the industry's first family of connections designed to meet the specific and different needs of each pipe size.

    All TurboTorque connections feature a proprietary double-start thread form, making them radically faster than competitive connections.

    TurboTorque's unique design reduces revolutions from stab to makeup by at least 50% to significantly cut drilling time and costs. Other benefits include increased torque capacity, optimized hydraulics, increased clearance and fishability, reduced risk of failure and extended life. Simply put, TurboTorque provides improved performance compared to XT, yet runs as fast or faster than API connections.

    TurboTorque connections have been thoroughly engineered and tested to validate both design and performance. Tests included finite element analysis, torque-to-yield, multiple make and break, comparative fatigue testing and several field trials.

    TurboTorque™ Design Philosophy

    For over 25 years, Grant Prideco has taken the lead in the development of rotary-shouldered connections. The double-shouldered HI-TORQUE™ (HT™) connection is still a high-performance workhorse of the drilling industry. Even so, the HT design was based on API thread forms, ultimately limiting performance. The XT design departed from the constraints of API with an improved thread form and reduced taper. This design optimization resulted in additional improvements in torque capacity and streamlined profiles. For completions, under-balanced drilling (UBD) and other pressure sensitive operations, the Grant Prideco™ XT-M™ connection provided the industry’s first pressure rated rotary shouldered connection.

    Still leading the industry, Grant Prideco has further refined the development and optimization of rotary shouldered connection design. TurboTorque connections are the industry’s first rotary-shouldered connections that are designed to meet the specific and different needs of each individual pipe size. Taking a “one size does not fit all” approach, the TurboTorque product line is composed of four distinct configurations, optimized to best meet some very specific objectives.

    For 3-1/2 to 4-1/2 inch sizes, connection torque capacity is of primary importance. The common use of these sizes makes speed of makeup more desirable than incremental hydraulic gains.

    The typical tool joint to pipe body torque and tension ratios for 5 to 5-7/8 inch sizes are relatively balanced. These sizes are commonly used offshore and in higher profile projects. Design must focus on speed of makeup and streamlined connection profiles for increased hydraulic performance.

    For the large 6-5/8 inch pipe size commonly run in elevated spread rate projects such as deep water, speed of makeup is a primary design objective. In addition, make-up torques can be excessive, at times surpassing the capacity of the rig equipment. Design parameters must be balanced to reduce the make-up torque and improve hydraulic performance.

    Features/Benefits

    DOUBLE-START THREAD

    TurboTorque™ connections are the industry’s first rotary-shoudered design to offer a double-start thread. Dual thread forms, 180 degrees apart, reduce the number of turns from stab to makeup by 50%. The increase in thread lead angle provides an increased torque capacity of up to 12%.  

    Benefits: Reduced rig time, reduced cost, increased torque capacity 

    Double-Start Thread Design

      

    STRONGER TOOL JOINTS  

    Standard drill pipe tool joints are made of steel with specified minimum yield strength of 120,000 psi (120 ksi SMYS). Traditionally, efforts to increase tool joint yield strength have resulted in reduced fracture toughness and increased susceptibility to fatigue crack propagation. TurboTorque connections are engineered specifically for use with 130 ksi SMYS material, while meeting the increased fracture toughness required by proprietary manufacturing standards. In addition, TurboTorque’s thread form and tool joint geometry have been  engineered to provide a step-change improvement in fatigue performance. 

    Benefits: Increased torque capacity, reduced connection profile, improved fishability, increased hydraulic performance, reduced cost.  

    Make-up Torque Comparison  

      

    OPTIMIZED CONNECTION TAPER 

    Taper is one of the controlling factors in the final configuration of a rotary-shouldered connection. TurboTorque’s taper is engineered to ensure a balance between the pin and box, maximizing fatigue resistance. The taper is selected to provide for maximum trade-off in torque capacity and speed of makeup. 

    Benefits: Balanced pin and box, fatigue resistance, reduced conneciton profile, improved fishability, increased hydraulic performance, reduced cost. 

      

    HIGH-PERFORMANCE THREAD FORM

    TurboTorque’s proprietary thread form is optimized or each of the four design configurations. The thread form incorporates a unique dual-root radius – larger than the root radii of API and even XT™ connections – significantly reducing peak stress in the thread roots.

    Benefits: Enhanced fatigue performance, reduced cost. 

    Thread Form Comparisons

      

    STRESS CONCENTRATION FACTOR

    The design evolution of TurboTorque connections led to the development of a novel approach for determining the Stress Concentration Factor (SCF) of rotary-shouldered connections (RSC). In most mechanical systems, SCF is defined as a ratio of peak stress to applied normal stress in a similarly strained area. Peak stress is the highest principal stress that normally occurs at a geometric discontinuity, usually a thread root in the case of a rotary-shouldered connection. Current industry methods for determining SCF do not consider the large pre-load stress induced by the make-up torque in a rotary-shouldered connection.

    Taking the large pre-load into account, Grant Prideco has developed a new methodology for more accurately predicting the worst case peak stress for a given pipe load. This more accurate method uses Finite Element Analysis (FEA) as the primary tool to explore the maximum peak stress trends in rotary-shouldered connections and to calculate the SCF. The Grant Prideco™ RSC SCF methodology provides an accurate method to compare the relative peak stress trends and SCF values among various rotary-shouldered connection designs to assist in evaluation and selection of connections for drilling, completion and open-water applications.

    The SCF values for TurboTorque390, TurboTorque585, API NC38 and 5-1/2 are shown for comparison in the adjacent table for various common tool joint sizes. TurboTorque connections provide a step-change improvement in peak stress reduction and enhanced fatigue performance while offering substantially more streamlined profiles.

    Benefits: More accurate prediction of peak stress and relative fatigue life, reduced cost. 

    Comparative SCF Values

    Specifications

    TurboTorque™’s performance improvements are best illustrated by a comparison to both an API connection and to XT™ for specific drill pipe sizes. The following drill pipe sizes with API connections are typically used:

    Offshore -

    • 3-1/2 in. 13.30 lb/ft EU S-135 Range2
    • 5-1/2 in. 24.70 lb/ft IEU S-135 Range2

    Onshore -

    • 4-1/2 in. 16.60 lb/ft IEU S-135 Range2

     

    Due to their streamlined profile, TurboTorque and XT connections permit use of a larger pipe size than do API connections for similar hole sizes.

    Offshore -

    • 4 in. 14.00 lb/ft IU S-135 Range2
    • 5-7/8 in. 23.40 lb/ft IEU S-135 Range2

    Onshore -

    • 5 in. 16.60 lb/ft IEU S-135 Range2

     

    The best fit API, XT and TurboTorque connections were selected for each pipe size. The results are shown in the table Performance Comparison - TurboTorque™, XT™ and API Assemblies below. The TurboTorque connections meet stringent Grant Prideco design criteria while providing a more compact profile resulting in improved clearance (fishability) and hydraulic efficiency. Also, TurboTorque provides make-up speeds comparable to or better than the API connections, resulting in efficient rig operations. TurboTorque connections offering the “torque on demand” feature provide improved torque capacity.

    TurboTorque™ Mechanical Characteristics

    Performance Comparison - TurboTorque™, XT® and API Assemblies

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