Low-Marking Plug Gripper With Serrated Teeth for High-Pressure Pipe Grip
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Solution Overview
Problem
Existing hydrostatic test plugs leave significant gripping marks on pipes, necessitating post-test repairs and additional work, and struggle to maintain a secure grip under high pressure conditions, especially with harder materials like high-alloy and fiberglass pipes.
Innovation Solution
Low-marking grippers with serrated teeth and controlled depth/height, featuring axial slots for flexibility, are designed to minimize pipe deformation by using a set of gripper segments that engage with the pipe wall, ensuring minimal marking depth of 0.005 inch and maintaining a secure grip.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If grippers are designed to bite into the pipe wall to secure the plug during high pressure testing, then the plug can withstand high pressure forces, but significant gripping marks are left on the pipe requiring post-test repairs
Solution Approach 1:
The gripper teeth are designed with controlled depth and height parameters, specifically limiting the bite depth to minimal levels. The teeth geometry is optimized to provide sufficient friction and mechanical interlocking for secure gripping while constraining the penetration depth to prevent excessive pipe wall deformation and marking.
Solution Approach 2:
The gripper segments feature localized serrated teeth with specific geometric properties at the contact points with the pipe wall. The teeth are designed with particular height, width, and spacing characteristics that provide maximum gripping force in the local contact zone while minimizing the overall impact on the pipe surface.
2Adaptability or versatility
If conventional grippers are used on harder pipe materials like high-alloy and fiberglass pipes, then the plug can be installed and secured, but the gripping marks become more significant and pipe damage increases
Solution Approach 1:
The gripper segments are constructed from composite materials that combine hardness for effective engagement with hard pipe materials (high-alloy, fiberglass) and toughness to prevent excessive deformation. The material composition is optimized to provide sufficient friction and mechanical interlocking with hard surfaces while maintaining elasticity to minimize permanent damage.
Solution Approach 2:
The gripper teeth geometry is specifically adapted for hard pipe materials, with modified depth, height, and spacing parameters compared to conventional grippers. The teeth are designed with shallower penetration depth and optimized spacing to distribute the gripping force across multiple contact points, reducing localized stress and deformation on hard pipe walls.
3Force
If gripper teeth with greater depth are used to ensure secure gripping, then the plug can withstand higher pressures, but the marking depth on the pipe increases
Solution Approach 1:
The gripping force is distributed across multiple segmented teeth arranged in circumferential rows around the gripper segment. Instead of relying on a few deep-biting teeth, numerous shallow-biting teeth work collectively to provide the necessary friction and mechanical interlocking, achieving high pressure withstanding capacity while maintaining shallow individual tooth depths for minimal marking.
Solution Approach 2:
The gripping mechanism transitions from relying primarily on vertical tooth depth to utilizing horizontal tooth spacing and circumferential distribution. Multiple rows of teeth arranged circumferentially provide distributed contact points that collectively generate the necessary gripping force through friction and shear resistance rather than deep penetration.
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 low-marking grippers provide minimal visible pipe damage, ensuring reliability and safety while withstanding high pressures, reducing post-test repair needs and maintaining a secure seal during testing.
Implementation Method 1
The gripper has a generally truncated pyramidal shape and engages, frictionally engages, grips, bites, or makes intimate contact with an inner diameter or outer diameter wall of a pipe or tube
Data Source
AI summary
A low-marking gripper for a hydrostatic test or isolation plug is provided. The gripper includes at least one gripper segment having a pipe or tube confronting surface with a plurality of separate rows of gripper teeth longitudinally-spaced apart on the surface. Each of the separate rows of gripper teeth comprising an alternating array of individual tips and gaps such that each row is serrated along its length. Each of the teeth has a height of 0.005 inch or less and a tip having an upper surface with an area of less than 0.0002 inch2. The gripper segment includes at least one longitudinal-extending slot extending therethrough to provide flexibility.