Type 4 HDPE Pressure Vessels for Refrigerated Gas Transport
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Solution Overview
Problem
Current pressure vessel systems for transporting gaseous fluids face challenges such as weight, corrosion, ductility issues, and inefficiencies in refrigeration, leading to potential failures and reduced capacity, especially for Type 4 pressure vessels made from extruded HDPE and injection-molded domes, which are prone to stress concentrations and corrosion, and have limitations in stability and operating pressure due to thin-walled designs.
Innovation Solution
A lightweight intermodal container system with low-temperature resistant Type 4 pressure vessels featuring blow-molded HDPE liners with thicker domed ends and butt-fusion-welded cylindrical sections, along with a polar port boss design using metallic components and crimp fittings to enhance sealing and stability, and a conical neck for impact resistance, integrated with a filament winding process using an integral winding shaft for improved structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If type 4 pressure vessels are made from extruded HDPE pipe and injection-molded domes, then weight is reduced, but stress concentration occurs at weld lines under refrigeration
Solution Approach 1:
The patent applies local quality by making the domed end portions have a greater wall thickness than the body portion. This localized thickening at the dome areas directly addresses the stress concentration problem at weld lines during refrigeration, while maintaining the overall lightweight characteristic of HDPE construction.
Solution Approach 2:
The patent uses composite materials by combining HDPE liner with filament winding (fiberglass or carbon fiber) to create a type 4 pressure vessel. This composite structure provides both the lightweight benefit of polymers and the structural strength needed to withstand refrigeration stresses without failure at weld lines.
2Weight of moving object
If type 3 pressure vessels use aluminum liners, then weight and ductility problems are overcome, but corrosion resistance deteriorates
Solution Approach 1:
The patent employs composite materials by using HDPE as the liner material instead of aluminum. This HDPE liner provides both the lightweight advantage and superior corrosion resistance needed for refrigerated natural gas storage, eliminating the corrosion problem inherent in aluminum-based type 3 vessels.
3Ease of manufacture
If type 3 pressure vessels are made with limited diameter seamless construction, then manufacturing cost is reduced, but the number of connections increases
Solution Approach 1:
The patent applies parameter changes by increasing the diameter of the pressure vessels. This allows for fewer vessels to be used in the same storage capacity, thereby reducing the total number of connections required. The seamless construction method is maintained for these larger diameter vessels, balancing manufacturing cost with reliability.
4Ease of manufacture
If injection-molded domes are used with thin walls, then manufacturing cost is reduced, but operating pressure capability is limited
Solution Approach 1:
The patent uses composite materials by combining the injection-molded HDPE dome with an external filament winding structure. This composite approach allows the thin-walled economical dome to achieve high operating pressure capability through the added strength of the fiberglass or carbon fiber winding, maintaining both low manufacturing cost and high pressure capability.
Solution Approach 2:
The patent employs spheroidality by using domed end portions with optimized curvature. This geometric design distributes stress more effectively across the dome structure, allowing thinner walls to withstand higher operating pressures while maintaining manufacturing economy.
5Quantity of substance
If refrigeration is applied to horizontal type 4 pressure vessels, then capacity efficiency is improved, but overturning risk increases
Solution Approach 1:
The patent applies spheroidality by using domed end portions instead of flat ends on horizontal pressure vessels. This curved geometry improves structural stability and resistance to overturning forces during refrigerated transport, while maintaining the capacity efficiency benefits of refrigeration.
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 system provides enhanced safety, capacity, and cost-effectiveness by reducing stress concentrations, corrosion risks, and operating pressure limitations, while maintaining structural integrity and allowing for efficient refrigeration and handling of gaseous fluids, even under refrigerated conditions.
Implementation Method 1
two or more liner parts designed to provide for a relatively-greater wall thickness at the domed end portions
Implementation Method 2
blow-molded HDPE liners with thicker domed ends and butt-fusion-welded cylindrical sections
Implementation Method 3
integrated with a filament winding process using an integral winding shaft for improved structural integrity
Implementation Method 4
polar port boss design using metallic components and crimp fittings to enhance sealing and stability
Data Source
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AI summary
A lightweight intermodal or road trailer based system for transporting refrigerated gaseous fluids is provided. The system includes an enclosed and insulated transportation housing, and a plurality of low-temperature resistant type 4 pressure vessels. The pressure vessels are at least three feet in diameter secured within the transportation housing for containing the gaseous fluids.