Tong Assembly Dual Load Cell Torque Control
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Solution Overview
Problem
Existing tong assemblies for making up and breaking out tubular connections face challenges in accurately measuring torque due to misalignment of force measuring sensors and size variations of tubulars, leading to potential loose or overly tight joints.
Innovation Solution
A tong assembly with a load transfer assembly that includes two load cells, one for measuring tension force during makeup and another for compressive force during breakout, along with a control system to select the appropriate load cell based on the operation, ensuring accurate torque measurement and prevention of joint misalignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single force measuring sensor is used in the tong assembly, then the device complexity is reduced, but the measurement precision deteriorates due to misalignment during makeup operations
Solution Approach 1:
The single force measuring sensor is divided into two separate load cells (first load cell and second load cell) positioned at different locations in the tong assembly. Each load cell measures force independently, and their combined measurements provide accurate torque data regardless of tong movement or alignment changes during makeup operations.
Solution Approach 2:
The two load cells are designed to serve multiple functions: the first load cell measures force during makeup operations, the second load cell measures force during breakout operations, and together they provide comprehensive torque measurement coverage for all operational phases, making the measurement system universally applicable.
2Device complexity
If torque measurement is converted from force measurement using a single sensor, then the device complexity is reduced, but the measurement precision deteriorates due to size variations of tubulars
Solution Approach 1:
The measurement system is segmented into two independent force measurement paths using two load cells, each capturing force data from different structural elements of the tong assembly. This segmentation allows the system to compensate for tubular size variations by combining measurements from multiple locations.
Solution Approach 2:
The control system receives force measurements from both load cells, processes the data to calculate torque, and uses the combined information to compensate for variations in tubular dimensions. The feedback loop ensures accurate torque measurement despite changes in tubular size.
3Productivity
If the tong assembly does not verify torque measurements, then the operation speed is increased, but the reliability deteriorates due to potential loose or overly tight joints
Solution Approach 1:
The control system performs preliminary verification of torque measurements by comparing data from both load cells before completing the makeup operation. This preliminary check ensures joint reliability without significantly delaying the overall operation, as the verification is automatically performed during the normal operational sequence.
Solution Approach 2:
The control system continuously monitors force measurements from both load cells and provides real-time feedback on torque application. This feedback mechanism allows the system to verify torque measurements and make adjustments if needed, ensuring reliable joint tightness while maintaining operational efficiency.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides precise torque measurement and control, preventing joints from being too loose or too tight, ensuring uniform tightness in tubular strings during makeup and breakout operations.
Implementation Method 1
a first load cell positioned to measure a first force exerted on the first link
Implementation Method 2
a second load cell positioned to measure a second force exerted on the second link
Data Source
Figure 1A
Figure 1B
Figure 1C~1D
AI summary
A tubular handling apparatus includes a power tong; a backup tong; and a load transfer assembly connected between the power tong and the backup tong. The load transfer assembly includes a first link having a first load cell positioned to measure a first force exerted on the first link; and a second link having a second load cell positioned to measure a second force exerted on the second link. The tubular handling apparatus may also include a tong control assembly configured to select the first load cell for use in a tubular makeup operation and to select the second load cell for use in a tubular breakout operation.