Flexible Tank Outer Cover Layout for 40-Foot Rupture Resistance
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Solution Overview
Problem
Conventional flexible tanks for larger shipping containers without bulkheads, such as 40 foot containers, are prone to rupture due to increased dynamic forces, and existing solutions like compartmentalization or reinforcement increase complexity, cost, and weight.
Innovation Solution
A freestanding flexitank design with a unique outer cover configuration, featuring a single lateral seam and two longitudinal seams, eliminating end seams and using a reinforced PVC material with a woven scrim, to withstand dynamic forces without additional weight or cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If conventional flexible tanks are used in 40 foot containers without bulkheads, then the tank can be placed in larger containers for increased cargo capacity, but the tank is prone to rupture due to increased dynamic forces from liquid movement during transport
Solution Approach 1:
The outer cover is divided into multiple panels (front panel, rear panel, first side panel, second side panel) connected by seams, with the rear panel featuring a curved configuration. This segmentation allows the structure to flex and distribute dynamic forces across multiple zones rather than concentrating stress at single points, reducing rupture risk while maintaining large volume capacity
Solution Approach 2:
The rear panel is specifically designed with a curved configuration to provide enhanced structural support at the location most susceptible to dynamic forces from liquid movement. This localized reinforcement addresses the specific stress pattern in 40 foot containers without bulkheads, improving reliability in the critical rear region while maintaining overall tank capacity
2Volume of moving object
If the outer cover is made larger to fit 40 foot containers, then the tank capacity increases, but the material requirements and manufacturing complexity increase
Solution Approach 1:
The outer cover is segmented into standard-sized panels that can be manufactured using conventional processes and then assembled into the large 40 foot container configuration. This allows the tank to achieve large capacity while maintaining manageable manufacturing complexity through modular panel construction rather than requiring a single large custom-molded piece
Solution Approach 2:
The rear panel incorporates a curved configuration that adds dimensional complexity to distribute stresses effectively, while the overall panel assembly approach maintains manufacturing simplicity through standardized cutting and joining processes for each panel
3Strength
If reinforcement is added to withstand dynamic forces, then the tank strength increases, but the weight and cost increase
Solution Approach 1:
The curved rear panel provides targeted reinforcement at the location most exposed to dynamic forces from liquid movement during transport. This localized geometric reinforcement increases strength where needed without adding material throughout the entire tank structure, thereby minimizing weight increase while achieving the required strength
Solution Approach 2:
The outer cover utilizes woven polypropylene material that provides high strength-to-weight ratio, and the curved rear panel configuration works in conjunction with this material properties to achieve enhanced strength without proportionally increasing weight
Data Source
AI summary
An exterior cover of a generally rectangular flexible tank for a 40 foot shipping container has longitudinal seams along the long sides of the flexible tank rather than at the ends. The exterior cover is air-tight and contains holes near the ends of the flexible tank. The exterior cover is made of a flexible vinyl material that is optimized for the flexitank. The flexible vinyl material consists of an inner scrim core of woven fibers coated with melted PVC which goes through the holes between the woven fibers.