Skid Assembly Load Distribution for Tank Car Valves
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Solution Overview
Problem
Railroad tank cars with protruding valves or fittings are prone to damage and leakage during derailment events due to inadequate protection from existing skid assemblies, which fail to effectively distribute loads and resist deformation.
Innovation Solution
A skid assembly with an external skid shell and internal reinforcement, featuring a bridge or truss design that spans clear of the tank, mounted independently of the tank structure, to distribute loads and resist deformation, thereby protecting protruding fittings like the Bottom Outlet Valve (BOV).
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If existing skid assemblies are used to protect protruding fittings, then some protection is provided, but they fail to effectively distribute loads and resist deformation during derailment
Solution Approach 1:
The skid assembly is divided into distinct functional components: an external skid shell for protection, internal reinforcement members for structural strength, and load spreading apparatus for load distribution. This segmentation allows each component to specialize in its function, with the load spreading apparatus specifically designed to distribute forces across multiple reinforcement bars, preventing concentrated loads that could cause failure
Solution Approach 2:
The load spreading apparatus and internal reinforcement are pre-installed on the tank car before derailment occurs. The footprint of the skid shell is designed to mate with reinforcement bars that extend axially along the tank, creating a pre-configured load path that activates automatically during impact, distributing forces before they can concentrate on single points
2Stability of the object's composition
If a skid assembly with internal reinforcement is mounted independently of the tank, then deformation resistance is improved, but the complexity of assembly increases
Solution Approach 1:
The internal reinforcement members serve multiple functions simultaneously: they provide structural strength to resist deformation, create a stable footprint for the skid shell, and distribute loads during impact. The footprint design that mates with reinforcement bars serves both as a mounting interface and as a load distribution mechanism, reducing the need for separate attachment hardware
Solution Approach 2:
The internal reinforcement members are positioned within the skid shell, with the reinforcement nested inside the protective outer shell. This nested arrangement allows the reinforcement to provide structural support while being protected by the shell, and the footprint of the shell accommodates the reinforcement bars, creating a compact integrated assembly
3Object-affected harmful factors
If the skid shell spans clear of the tank with reinforcement bars, then tank integrity is maintained, but the structural support requirements increase
Solution Approach 1:
The skid assembly acts as an intermediary structure between the external environment and the tank. The load spreading apparatus and internal reinforcement create a protective platform that intercepts and distributes impact forces across multiple reinforcement bars, preventing concentrated forces from directly contacting and puncturing the tank shell
Solution Approach 2:
The structural support function is segmented from the tank itself and transferred to the skid assembly components. The footprint mates with reinforcement bars that extend from the tank, creating discrete load transfer points that distribute forces across multiple locations, reducing the structural burden on any single point of the tank
Data Source
AI summary
A railroad tank car may have external fittings, such as a bottom opening valve, that protrude from the bottom of the tank car tank. In a derailment the tank car tank may meet the ground. A tank skid plate assembly has an accommodation in which to shelter such fittings. The skid plate assembly has a shell with tapered ramps at either end. It mounts to tank reinforcement structure, such as reinforcing bars. Reinforcements may be mounted in the lee of the shell. Those reinforcements may be mounted to the shell only, without welding connection to the tank car tank. The reinforcements may be, or combine with the shell to define either a bridge or a truss that spans the space between the reinforcement bars. The assembly may have an access passageway, such as for admitting a heating pipe. The assembly may include lateral and longitudinal internal webs for providing crush resistance.