Jet Pump Sensing Line T-Bolt Clamp With Folded Spring Plate
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Solution Overview
Problem
The existing T-bolt clamp assemblies in nuclear reactors, used to prevent resonant vibration of pressure sensing lines, face issues with preload maintenance due to wear, corrosion, and stress exceeding allowable limits, leading to potential failure and plant shutdown.
Innovation Solution
The design incorporates an L-beam folded spring plate as the top plate in the T-bolt clamp assembly, providing additional flexibility and elastic strain to maintain preload, replacing Belleville washers and distributing elastic strain over a longer load path, thus reducing stress and ensuring secure clamping of the sensing lines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Belleville washers are used to add flexibility and elastic strain to the bolted connection, then preload maintenance is improved, but stress in the washers exceeds allowable limits for Ni—Cr—Fe alloy X-750 material
Solution Approach 1:
The patent changes the physical parameters of the top plate by introducing an L-shaped folded beam configuration with specific geometric dimensions (leg lengths, thickness, corner radius). This transforms the rigid top plate into a flexible structure that provides elastic compliance through controlled deformation of the L-shaped beam, replacing the Belleville washers while maintaining preload through the beam's inherent flexibility.
Solution Approach 2:
The patent extracts and removes the Belleville washers from the assembly, eliminating the stress concentration problem they caused in the Ni—Cr—Fe alloy X-750 material. The functionality previously provided by the washers (elastic compliance and preload maintenance) is transferred to the L-shaped folded beam in the top plate, which has superior stress distribution characteristics.
2Strength
If a stiff T-bolt attachment is used, then structural strength is improved, but elongation is small such that wear, corrosion, and relaxation diminish required preload
Solution Approach 1:
The patent modifies the top plate's geometric parameters to create an L-shaped folded beam with optimized leg lengths and thickness. This configuration provides controlled flexibility that increases the effective elongation of the bolted connection, creating sufficient compliance margin to accommodate wear, corrosion, and relaxation while maintaining the required preload force.
3Strength
If Ni—Cr—Fe alloy X-750 material is used for construction, then strength and corrosion resistance are improved, but stress exceeds allowable limits under the Belleville washer design
Solution Approach 1:
The patent removes the Belleville washers that caused excessive stress concentration in the Ni—Cr—Fe alloy X-750 material. By eliminating this stress-concentrating component, the design allows the high-strength material to be utilized effectively without exceeding allowable stress limits.
Solution Approach 2:
The patent changes the stress distribution parameters by replacing the Belleville washer load path with an L-shaped folded beam structure. This new configuration distributes the clamping load more favorably across the Ni—Cr—Fe alloy X-750 material, reducing peak stresses while maintaining the required clamping force.
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
This solution maintains preload effectively, reducing stress and elongation, and provides a more reliable vibration support function while meeting stricter stress corrosion limits, ensuring continuous operation and reducing the risk of plant shutdown.
Implementation Method 1
providing additional flexibility and elastic strain to maintain preload
Implementation Method 2
to prevent resonant vibration of the pipe
Data Source
AI summary
A remotely installable piping support attachment assembly employs a T-bolt type fastener for clamping a relatively smaller instrumentation pipe, e.g., the jet pump sensing line, to the wall of an adjacent structure. The attachment assembly includes a T-bolt, a split pipe clamp support, a ratchet nut with peripheral ratchet teeth, and a ratchet lock washer. When the nut is tightened on the threaded shank of the T-bolt, a top plate and an anchor of the split pipe clamp support are pressed together to clamp the jet pump sensing line therebetween. The top plate is defined by an L-beam folded spring plate comprised of first and second plate parts disposed generally in parallel and joined at a living hinge flex joint so that said plate parts each have a free end edge remote from said flex joint, the free end edges being spaced apart to define a gap therebetween without preload.