Water-Degradable Purge Dam Plates for Pressure-Stable Pipe Welding
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Solution Overview
Problem
Conventional water-degradable purge dams are not suitable for high air flow environments, such as underwater pipelines, as they cannot withstand bidirectional air pressure fluctuations and are difficult to remove after welding due to incomplete degradation.
Innovation Solution
A water-degradable welding purge dam apparatus with interconnected blocking plate assemblies formed from materials like water-degradable paper or polymers, which are designed to provide low air permeability, structural strength, and easy degradation using aqueous fluids, featuring fluid flow apertures for rapid dissolution and self-retention mechanisms to prevent gas displacement during welding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional water degradable purge dams are used, then they can be easily removed after welding by dissolving with water, but they cannot withstand bidirectional air pressure fluctuations in high air flow environments
Solution Approach 1:
The purge dam is divided into multiple blocking plates stacked together, with each plate contributing to the overall structural strength to withstand air pressure fluctuations while maintaining water degradability for easy removal
Solution Approach 2:
The blocking plates are made from composite or laminated water degradable materials that provide both the necessary mechanical strength to resist bidirectional air pressure surges and the chemical property of dissolving in water for easy removal after welding
2Reliability
If blocking members made from foam material are used to prevent air flow, then they can block air pressure fluctuations, but they are difficult to remove after welding and may dislodge if air pressure fluctuations are large
Solution Approach 1:
The purge dam uses water degradable blocking plates that are designed to be temporary and easily disposed of after serving their purpose, dissolving in water during hydrostatic testing or flushing to enable simple removal without dislodging or leaving residue
Solution Approach 2:
The material properties of the blocking plates change in response to environmental conditions - they maintain structural integrity and low air permeability during welding, then undergo degradation when exposed to water, transforming from a strong blocking structure to a dissolvable form for easy removal
3Productivity
If conventional purge dams are used, then they can be placed in close proximity to the weld zone, but they cannot prevent purge gas displacement in high air flow environments
Solution Approach 1:
The purge dam consists of multiple stacked blocking plates that create a more effective barrier against bidirectional air flow, allowing the dam to be positioned closer to the weld zone without risking purge gas displacement
Solution Approach 2:
The blocking plates are designed with controlled porosity or surface characteristics that provide low air permeability to prevent purge gas displacement while maintaining structural strength against air pressure fluctuations
4Ease of operation
If water degradable paper purge dams are used, then they can degrade completely for easy removal, but they lack the structural strength to withstand air pressure fluctuations
Solution Approach 1:
The blocking plates are constructed from composite or laminated water degradable materials that combine the strength properties needed to withstand bidirectional air pressure surges with the degradability properties that allow complete dissolution in water for easy removal
Solution Approach 2:
The purge dam is segmented into multiple blocking plates, where the stacked configuration provides cumulative structural strength to resist air pressure fluctuations while each individual plate remains thin enough to degrade completely when exposed to water
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 apparatus effectively maintains a purge gas shield in high air flow environments and facilitates rapid and complete removal after welding by withstanding air pressure fluctuations and degrading efficiently under hydrostatic pressure testing or flushing.
Implementation Method 1
designed to provide low air permeability, structural strength, and easy degradation using aqueous fluids
Implementation Method 2
facilitates rapid and complete removal after welding by withstanding air pressure fluctuations and degrading efficiently under hydrostatic pressure testing or flushing
Data Source
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AI summary
A water-degradable welding purge dam apparatus for purging a weld zone of a pipe assembly having first and second pipes having respective first and second pipe ends to be welded together at a root gap. The purge dam apparatus includes a blocking plate assembly having an outer blocking plate, an inner blocking plate, and zero or more interior blocking plates. The blocking plate assembly may be formed from one or more water degradable materials to facilitate removal of the purge dam apparatus from the pipe assembly using an aqueous fluid following welding. At least one of the blocking plates may include a plurality of fluid flow apertures to aid distribution of the aqueous fluid through the blocking plate assembly. If desired, first and second ones of the blocking plate assembly may be ganged together by an interconnection assembly to form a ganged set of blocking plate assemblies.