Thief Hatch Assembly Blind Threaded Mounting Seal
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Solution Overview
Problem
Conventional thief hatches on storage tanks experience gas leaks around the bolts and through the mounting holes, which are not effectively addressed by existing rubber gaskets and seals, leading to environmental concerns and compliance issues.
Innovation Solution
A thief hatch assembly utilizing a flange adapter with blind threaded mounting holes that prevent gas escape, featuring a housing with a cover that opens at a predetermined pressure and includes seal rings to seal the mounting surfaces, allowing for attachment to existing tanks without full-through holes, thereby preventing gas leaks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional through holes with rubber gaskets are used to attach thief hatches to storage tanks, then the attachment is simple and secure, but gas leaks occur around the bolts and through the mounting holes
Solution Approach 1:
The mounting hole is divided into two separate openings: one for the bolt to pass through and another for the gasket to seal against. This segmentation prevents gas from traveling through the mounting hole while maintaining secure attachment, directly resolving the gas leakage problem associated with conventional through-holes.
Solution Approach 2:
A gasket is introduced as an intermediary element between the thief hatch flange and the storage tank flange. The gasket creates a sealing surface that blocks gas leakage paths, while the bolt provides mechanical fastening through a separate opening, thus eliminating the direct gas leakage route through the mounting hole.
2Object-generated harmful factors
If blind threaded holes are used in the thief hatch flange, then gas leaks are prevented, but the attachment requires more complex threading operations
Solution Approach 1:
The mounting structure is segmented into separate functional elements: blind threaded holes for gas-tight fastening and separate gasket sealing surfaces. This segmentation achieves gas leakage prevention while the gasket compensates for any manufacturing tolerances, simplifying the overall assembly process despite the threaded holes.
Solution Approach 2:
The blind threaded holes in the thief hatch flange create a gas-tight connection that serves its own sealing function, eliminating the need for additional sealing components in some configurations. The structure itself provides the sealing mechanism through the threaded interface.
3Object-affected harmful factors
If existing thief hatches are retrofitted with blind threaded holes, then environmental compliance is improved, but the modification requires significant structural changes
Solution Approach 1:
Instead of modifying the existing thief hatch to use blind threaded holes (complex retrofit), the solution inverts the approach by providing a separate flange adapter assembly that interfaces with the existing through-holes. This adapter contains the blind threaded holes and sealing surfaces, achieving environmental compliance without altering the original thief hatch structure.
Solution Approach 2:
A flange adapter serves as an intermediary component between the existing thief hatch and the storage tank. This adapter incorporates blind threaded holes and gasket sealing surfaces, allowing existing thief hatches to achieve gas-tight connections without requiring complex structural modifications to the original device.
4Reliability
If multiple seals are provided between mounting surfaces, then gas leakage is reduced, but the assembly becomes more complex and harder to install
Solution Approach 1:
Multiple sealing functions are merged into a single gasket component that interfaces with both the thief hatch flange and the storage tank flange. This single gasket provides comprehensive sealing across all mounting surfaces, maintaining high seal effectiveness while simplifying installation by eliminating the need to install multiple separate seals.
Solution Approach 2:
A single gasket acts as an intermediary sealing element between the thief hatch assembly and the storage tank. This gasket consolidates multiple sealing functions into one component that can be installed in a single operation, achieving reliable gas leakage prevention without increasing installation complexity.
Data Source
AI summary
A thief hatch assembly for a storage tank includes a housing and a cover that rests on an upper surface of the housing to seal and maintain a pressure within the storage tank. The thief hatch cover is configured to open at a predetermined set pressure to relieve excess pressure from the storage tank. The thief hatch assembly is attached to the storage tank using blind threaded mounting holes to prevent escape of gases from the storage tank through the mounting holes. In one embodiment, the blind threaded holes are provided in a flange adapter that mounts between the thief hatch housing and the storage tank. In another embodiment, the blind threaded holes are provided in a flange adapter that is welded to the storage tank. In another embodiment, the blind threaded holes are provided in the base of the thief hatch housing. Seals are provided between the mounting surfaces.