Arcuate Pipe Joint Restraint with Segmented Clamping
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Solution Overview
Problem
The increasing radial wall thickness reduction and pressure ratings in fluid-transporting pipelines pose a risk of failure in pipes and pipe joint restraint devices, as they are subjected to internal fluid pressure and separation forces.
Innovation Solution
A pipe joint restraint apparatus comprising arcuate members with chamfers and ridges that clamp onto pipes, utilizing fasteners and tie rods to resist axial separation and shear failure, while the chamfers and tapering inside surfaces enhance engagement and reduce bending stresses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If pipe wall thickness is reduced to achieve lighter and more efficient pipes, then weight and material usage are improved, but the risk of failure under pressure and the strength of pipe joint restraint devices deteriorate
Solution Approach 1:
The restraint device is divided into multiple arcuate members that wrap around and clamp onto the pipes individually. Each arcuate member acts as an independent clamping unit, distributing the restraint forces across multiple contact points. This segmentation allows the device to maintain high clamping forces on thin-walled pipes without requiring excessive overall structural strength, thereby resolving the contradiction between reduced pipe weight and maintained strength.
Solution Approach 2:
The arcuate members feature localized high-strength features at critical contact points, including chamfers at the clamping surfaces and ridges that concentrate clamping forces. These local quality enhancements ensure that sufficient clamping force is applied to thin-walled pipes at specific locations without requiring the entire pipe or restraint device to be uniformly thick-walled, thus maintaining strength while allowing overall weight reduction.
2Reliability
If arcuate members clamp onto pipes with high clamping forces to prevent separation, then connection reliability is improved, but shear failure risk in thin-walled pipes increases
Solution Approach 1:
The clamping force is segmented and distributed across multiple arcuate members that contact the pipe at different locations. Instead of applying a single concentrated clamping force that could cause shear failure, the force is divided into multiple smaller contact points, reducing the shear stress on any single point of the thin-walled pipe while maintaining overall connection reliability.
Solution Approach 2:
The arcuate members are curved to match the pipe circumference, creating a conformal contact that distributes clamping forces evenly around the pipe. The chamfers on the arcuate members further distribute the contact stress over a larger surface area rather than concentrating it at sharp edges. This curvature-based design reduces shear failure risk by eliminating stress concentration points while maintaining reliable clamping.
3Productivity
If fasteners are positioned close to the pipe surface to maximize clamping efficiency, then clamping effectiveness is improved, but bending stresses in fasteners increase
Solution Approach 1:
The fastener openings are offset axially from the plane of the arcuate member, creating a three-dimensional configuration where the fastener does not lie in the same plane as the clamping surface. This axial offset positions the fastener in a different dimensional plane, allowing it to resist bending moments more effectively while still maintaining efficient clamping force transmission to the pipe surface.
Solution Approach 2:
The offset fastener configuration acts as an intermediary mechanical arrangement between the clamping force application point and the structural support. By positioning the fastener opening axially offset from the arcuate member plane, the design creates a mechanical lever arm that reduces bending stresses in the fastener while maintaining the clamping efficiency needed for effective pipe restraint.
Data Source
AI summary
An arcuate member is clamped onto a pipe so that a protrusion or ridge penetratingly engages the outside surface of the pipe.