Double Block and Breathe Orifice Fitting Sealing
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Solution Overview
Problem
In pipeline operations, existing orifice flowmeters face challenges in maintaining fluid containment during orifice plate replacement or removal, as high pressures can lead to unintentional fluid release, necessitating systems that provide reliable fluid tight barriers during both normal flow and maintenance operations.
Innovation Solution
The implementation of a double block and bleed system within the orifice fitting, which includes a multi-chamber configuration with sealing assemblies and vent valves to create multiple fluid tight barriers, allowing for controlled pressure regulation and fluid containment during orifice plate installation, removal, and normal operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single sealing system is used in the orifice fitting, then the device complexity is reduced, but the reliability of fluid containment during orifice plate replacement is insufficient under high pressure conditions
Solution Approach 1:
The sealing system is divided into multiple independent sealing assemblies (first sealing assembly with first sealing element, second sealing assembly with second sealing element) positioned at different locations within the orifice fitting. Each sealing assembly creates a separate fluid tight barrier, so that if one sealing fails, the other continues to contain the fluid. This segmentation of the sealing function directly addresses the contradiction by improving reliability through redundancy while maintaining manageable complexity through modular design.
Solution Approach 2:
The multiple sealing assemblies are positioned to create progressive fluid tight barriers before fluid can escape during orifice plate removal. The first sealing assembly provides initial containment, and the second sealing assembly provides backup containment, cushioning against the harmful effect of potential sealing failure under high pressure conditions.
2Reliability
If multiple valves and sealing assemblies are added to create fluid tight barriers, then the reliability of fluid containment improves, but the ease of operation during orifice plate removal deteriorates
Solution Approach 1:
The multiple sealing assemblies and valves are pre-configured in specific positions within the orifice fitting before maintenance operations begin. The first sealing assembly is positioned between the orifice plate and the process fluid, while the second sealing assembly is positioned to provide backup containment. This preliminary arrangement ensures that fluid tight barriers are already in place and properly positioned, eliminating the need for complex setup procedures during orifice plate removal and maintaining ease of operation.
Solution Approach 2:
The sealing assemblies act as intermediaries between the process fluid and the external environment, creating fluid tight barriers that allow maintenance personnel to safely remove or replace orifice plates without direct exposure to high pressure fluid. The intermediaries (sealing elements) enable the maintenance operation to proceed safely while maintaining system integrity.
3Object-affected harmful factors
If a double block and bleed system with multiple sealing assemblies is implemented, then the harmful effect of fluid leakage is reduced, but the device complexity increases
Solution Approach 1:
The fluid containment function is segmented into multiple independent sealing assemblies positioned at different locations within the orifice fitting. Each sealing assembly creates a separate fluid tight barrier, preventing fluid leakage through redundant containment. The first sealing assembly provides primary containment, while the second sealing assembly provides secondary containment, effectively reducing the harmful effect of fluid leakage to near zero while maintaining manageable structural complexity through modular design.
Solution Approach 2:
The sealing assemblies are nested within the orifice fitting structure, with each sealing assembly contained within the same general housing or body. This nesting arrangement allows multiple sealing systems to coexist within a compact space, reducing the overall device complexity while still providing multiple fluid tight barriers to prevent fluid leakage.
Data Source
AI summary
An orifice fitting includes a body, an orifice plate mounted in the body, and an orifice plate transfer passage within the body. The orifice plate transfer passage includes a shoulder, and the orifice plate is movable through the passage. In addition, the orifice fitting includes a sealing assembly disposed in the orifice plate transfer passage. The sealing assembly includes a sealing insert including a first section and a second section. In addition, the sealing assembly includes a first sealing member configured to create a first fluid tight barrier between the second section and the orifice plate transfer passage. Further, the sealing assembly includes a second sealing member configured to create a second fluid tight barrier between the shoulder and the first section. Still further, the sealing assembly includes a subchamber within the orifice plate transfer passage between the first fluid tight barrier and the second fluid tight barrier.