Mechanical Seal Assembly for Remote Tubular Opening Repair
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Solution Overview
Problem
Existing methods for sealing openings in tubular objects within nuclear power plants, particularly in feedwater spargers, are inadequate for inaccessible locations and do not ensure a reliable, leak-proof seal, especially when foreign material needs to be removed.
Innovation Solution
A mechanical seal assembly comprising a precision machined seal plate, a strongback, and bolts with integrated crimp cups is used to create a seal that can be installed remotely, using EDM to cut an elliptical opening for foreign material removal and then sealing it with a stainless steel stopper and bolts that provide a customizable, 100% leak-proof or less-than-100% seal depending on requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing sealing methods are used in inaccessible locations, then installation is simplified, but sealing reliability is insufficient and leak-proof performance cannot be ensured
Solution Approach 1:
The sealing device is divided into multiple independent components: a seal plate that contacts the inner surface of the tubular object, a strongback that contacts the outer surface, and multiple bolts that connect them. This segmentation allows each component to be independently manufactured, installed, and adjusted, enabling reliable sealing in inaccessible locations while simplifying the installation process through modular assembly.
Solution Approach 2:
The seal plate is inserted through an opening in the tubular object from the inside, while the strongback is attached to the outside surface. The bolts pass through both components, creating a nested configuration where the seal plate is positioned within the tubular object and the strongback is positioned outside, with both components working together to create the seal.
2Reliability
If a seal is made 100% leak-proof, then sealing performance is maximized, but system flexibility and adaptability are reduced
Solution Approach 1:
The sealing system is designed to be adjustable rather than fixed. The number of bolts, their positioning, and the configuration of the seal plate can be dynamically modified based on the specific sealing requirements. This allows the system to adapt to different opening sizes, shapes, and locations while achieving the required level of seal integrity, whether 100% leak-proof or less stringent requirements.
Solution Approach 2:
The sealing device is designed as a universal solution that can be applied to various tubular objects with different dimensions, materials, and opening configurations. The seal plate and strongback can be customized in size and shape, and the bolt pattern can be adjusted to accommodate different sealing requirements, making the system versatile for multiple applications in nuclear power plants.
3Manufacturing precision
If manual installation methods are used, then installation precision can be achieved, but radiation exposure and installation time increase
Solution Approach 1:
The seal plate is pre-machined with precise dimensions and surface finishes to ensure proper sealing contact. The bolts are pre-assembled with the seal plate, and the entire assembly can be pre-positioned before final installation. This preliminary preparation ensures high installation precision while reducing the time required for on-site assembly in the nuclear power plant environment.
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 mechanical seal assembly effectively seals openings in nuclear power plant tubular objects, allowing for foreign material removal and providing a reliable, customizable seal that can be installed and maintained remotely, ensuring minimal radiation exposure and maintaining system integrity.
Implementation Method 1
using EDM to cut an elliptical opening for foreign material removal
Data Source
Figure 1
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AI summary
A method for sealing an opening extending radially from an outer circumferential surface to an inner circumferential surface of a tubular object in a nuclear power plant includes inserting a stopper from outside of the outer circumferential surface through the opening into the tubular object; and actuating a fastener from the outside of the circumferential surface to force the stopper radially outward to seal the opening. A mechanical seal assembly for plugging an opening in a tubular object by contacting an inner circumferential surface of the tubular object includes a stopper configured for insertion into an interior of the tubular object for plugging the opening. The stopper includes a surface configured for matching the inner circumferential surface of the tubular object. The mechanical seal assembly also includes a fastener passing through a hole in the stopper such that the fastener is actuatable from outside of the tubular object to force the surface of the stopper against the inner circumferential surface of the tubular object.