Split Spider Assembly Preload Joint for Drilling
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Solution Overview
Problem
Spider assemblies used for supporting wellbore tubulars face issues with excessive axial deflection due to their large diameter and the need for disassembly, which can hinder transportation and emergency situations, and may interfere with hydraulic actuators.
Innovation Solution
A sectional spider support assembly comprising two circular plates with spacers and clamping blocks that create a preload force between semi-circular, c-shaped halves, reducing axial deflection and allowing for easier disassembly and transportation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the spider assembly is made into sections for transportation and emergency disassembly, then the ease of operation and adaptability improve, but the axial deflection increases due to joint flexibility
Solution Approach 1:
The spider assembly is divided into multiple sections that can be separated for transportation or emergency situations. Each section contains circular plates with c-shaped halves that can be attached and detached. This segmentation enables easy disassembly while maintaining structural integrity when assembled.
Solution Approach 2:
Clamping blocks are positioned with their faces recessed from the ends of the c-shaped legs by a specific distance (0.015" to 0.030"). This preliminary positioning creates a gap (0.030" to 0.060") that allows the application of preload force through bolts, which compresses the plate ends together to reduce axial deflection at the joint.
2Adaptability or versatility
If the spider assembly is made into sections with pin and finger-joints, then the adaptability for transportation improves, but the manufacturing precision and structural stability deteriorate due to excessive deflection
Solution Approach 1:
The invention changes the mechanical parameters of the joint by introducing clamping blocks with recessed faces and applying preload force through bolts. This transforms the joint from a flexible pin and finger configuration to a preloaded compressed structure, reducing axial deflection from greater than 1/2" to minimal deflection that maintains hydraulic actuator alignment precision.
3Ease of manufacture
If the spider assembly uses traditional joints, then the ease of manufacture improves, but the reliability of hydraulic actuators deteriorates due to misalignment from deflection
Solution Approach 1:
The clamping blocks are designed with faces recessed from the ends of the c-shaped legs by a predetermined distance (0.015" to 0.030"). This preliminary design feature enables the application of preload force that compresses the plate ends together, ensuring proper alignment and reliability of hydraulic actuators while maintaining ease of assembly through bolt fastening.
4Force
If the spider assembly is made into large diameter sections, then the load bearing capacity improves, but the ease of transportation worsens due to size constraints
Solution Approach 1:
The large diameter spider assembly is segmented into multiple sections that can be attached together. Each section contains circular plates that can be separated into c-shaped halves for compact transportation. When assembled, the sections form a complete large-diameter structure capable of bearing heavy loads, while the segmentation enables transportation through standard routes by separating the sections.
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 preload force significantly reduces axial deflection, enabling the assembly to function more like a continuous ring, supporting heavy loads with minimal deflection and facilitating emergency disassembly and transportation.
Implementation Method 1
Bolts are placed through holes in each block and tightened until the block faces are drawn together. As the clamping blocks are drawn together, the ends of the plates forming each c-shape are compressed towards the ends of the adjacent plates, thereby creating a preload force between the two sections.
Implementation Method 2
The preload force on the two halves permits the overall assembly to perform more like a continuous ring. The preload provides a significant amount of stiffness in the assembly and reduces the axial deflection associated with axial forces acting on the spider assembly.
Data Source
AI summary
A spider assembly is a round platform with a central bore used to support sections of casing as the sections of casing are joined to one another and lowered below a drilling platform. The spider assembly comprises two c-shaped section joined together at two seams, one seam at the end of each leg of the c-shape. A clamping plate is used to join each seam and apply a preload force on the joint. The preload force minimizes axial deflection at the joint.