Skid-Mounted Cold Box Bolt Assembly to Eliminate On-Site Welding
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Solution Overview
Problem
The existing skid-mounted cold box assembly methods require extensive on-site welding and nondestructive testing, leading to increased operational costs, time, and potential quality issues due to overhead work and crane usage, which affects the efficiency and airtightness of the cold box.
Innovation Solution
The method involves prefabricating structures with I-shaped and L-shaped frame sections and using friction-type high-strength bolts to connect ring beams between adjacent prefabricated structures, eliminating the need for on-site welding and nondestructive testing, and ensuring airtightness with neoprene washers and bolted connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If full penetration welding is adopted for joining nodes of prefabricated structures on site, then connection strength is improved, but operational cost and time increase significantly
Solution Approach 1:
The patent applies preliminary action by pre-assembling and pre-welding the steel structural framework, panels, and internal components into complete prefabricated structures in the factory before transportation. All welding operations are completed in advance under controlled conditions, eliminating the need for time-consuming on-site welding and nondestructive testing, thus resolving the contradiction between connection strength and assembly time.
Solution Approach 2:
The patent segments the cold box into multiple complete prefabricated structures (upper structure, lower structure, and intermediate structures) that are independently assembled in the factory. Each segment includes the steel framework, panels, insulation, and all internal equipment, allowing parallel fabrication and eliminating sequential on-site construction, thereby reducing total assembly time while maintaining structural integrity.
2Strength
If full penetration welding is adopted for joining nodes of prefabricated structures on site, then connection strength is improved, but operational cost increases
Solution Approach 1:
The patent applies preliminary action by pre-assembling and pre-welding the steel structural framework, panels, and internal components in the factory where conditions are controlled. This eliminates the need for expensive on-site welding operations and nondestructive testing, reducing operational costs while maintaining connection strength through factory-quality welding.
Solution Approach 2:
The patent enables self-service by designing the prefabricated structures with self-aligning features and pre-drilled connection holes that allow for quick mechanical assembly on site without requiring expensive welding equipment and specialized welding teams, thereby reducing manufacturing and operational costs.
3Ease of operation
If crane is mobilized for lifting upper prefabricated structure on site, then assembly is enabled, but efficiency of crane circulation decreases
Solution Approach 1:
The patent segments the cold box into multiple smaller prefabricated structures that can be lifted and assembled in sequence. This reduces the lifting weight and complexity for each crane operation, enabling faster assembly cycles and improving crane circulation efficiency compared to lifting one large structure.
Solution Approach 2:
The patent applies preliminary action by pre-assembling all components into complete prefabricated structures in the factory, so that on-site assembly requires only simple lifting and positioning operations. This minimizes the duration and complexity of crane operations, improving crane circulation efficiency while maintaining assembly capability.
4Reliability
If on-site welding is performed for joining panels, then airtightness is achieved, but assembly time and cost increase
Solution Approach 1:
The patent applies preliminary action by pre-assembling the steel framework and attaching all panels with proper sealing in the factory under controlled conditions. This ensures airtightness is achieved through factory-quality workmanship while eliminating time-consuming on-site welding and sealing operations.
Solution Approach 2:
The patent changes the working conditions parameter by moving the welding and sealing operations from on-site environmental conditions to controlled factory conditions. This parameter change improves both the quality of airtightness seals and the efficiency of the assembly process by eliminating weather-related delays and overhead work challenges.
Data Source
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AI summary
The present invention relates to a skid-mounted cold box and its prefabricated structure and assembly method. Each prefabricated structure includes a framework and a first panel that is used to enclose sides of the framework. Ring beams of two adjacent prefabricated structures are connected through bolts on site. A second panel connected through bolts encloses the gap between ring beams of the two adjacent prefabricated structures from sides. The present invention cancels all field welding seams and omits the field welding and nondestructive testing operations. The crane can be dismissed after the upper prefabricated structure of the cold box is lifted into place and bolts corresponding to columns on ring beams are connected. The present invention guarantees the connection strength of steel structures relying on bolt-based connection between ring beams and the second panel connected through bolts guarantees the airtightness of the cold box. This effectively reduces field assembly work and saves time and cost.