Elbow Clamp Assembly for Core Spray Line Weld Repair
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Solution Overview
Problem
The welds in the core spray line of boiling water nuclear reactors are susceptible to intergranular stress corrosion cracking (IGSCC), which can lead to structural integrity loss and separation of the P4a weld, compromising the delivery of cooling water to the reactor core.
Innovation Solution
An elbow clamp assembly that structurally supports or replaces the connection between the main pipe and the elbow pipe, comprising upper and lower clamp bodies connected by a clamp bolt, an elbow boss, and a cross bolt, with a locking mechanism and securing mechanism to ensure secure attachment and prevent unwanted movement, allowing for remote installation and adaptation to varying pipe sizes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If welding is used to connect the core spray line to the elbow, then a permanent connection is achieved, but the weld joint becomes susceptible to intergranular stress corrosion cracking
Solution Approach 1:
The patent replaces the welded mechanical system with a mechanical fastening system using clamp bodies, bolts, and weldless connectors. This substitution eliminates the P4a and P4b weld joints that are susceptible to IGSCC, while maintaining connection strength through distributed bolt fastening across multiple attachment points.
Solution Approach 2:
The invention extracts and removes the vulnerable weld joint section (P4a weld) from the system by introducing a weldless connector that physically separates the clad pipe from the elbow, eliminating the harmful weld metal interface that is prone to stress corrosion cracking.
2Strength
If a rigid clamp assembly is used to replace the weld, then structural integrity is improved, but fluid flow resistance increases
Solution Approach 1:
The patent employs thin-walled clamp bodies that conform to the external geometry of the pipe without significantly protruding into the fluid flow path. The clamp assembly is designed with minimal interference to the internal flow cross-section, reducing energy loss while maintaining external structural integrity.
3Manufacturing precision
If the clamp assembly is designed to fit precise pipe dimensions, then installation precision is improved, but adaptability to varying pipe sizes is reduced
Solution Approach 1:
The clamp assembly incorporates adjustable elements such as multiple bolt positions, flexible clamp bodies, and variable geometry connectors that allow the same basic design to adapt to different pipe diameters and slight dimensional variations, maintaining both precision fit and versatility.
Solution Approach 2:
The weldless connector design serves multiple functions: it provides structural connection, accommodates varying pipe dimensions through design flexibility, and maintains flow passage. The universal design can be applied across different pipe sizes within a range, reducing the need for custom-fitted components.
4Stability of the object's composition
If weld repair procedures are used to fix cracked joints, then the original weld structure is preserved, but the complexity of repair procedures increases
Solution Approach 1:
Instead of attempting to repair the complex cracked weld structure through multi-step weld repair procedures, the invention extracts the problematic weld joint entirely and replaces it with a simpler mechanical fastening system that is easier to install and inspect.
Data Source
AI summary
An elbow clamp assembly structurally supports or replaces a connection between a main pipe and an elbow pipe. The elbow clamp assembly includes an upper clamp body and a lower clamp body securable on opposite sides of the main pipe in facing relation. The upper and lower clamp bodies are connected by a clamp bolt extendable through the main pipe. An elbow boss is securable to the elbow pipe, and a cross bolt is extendable through the elbow pipe and connected between the elbow boss and the clamp bolt.