Multi-Double Block and Bleed Orifice Fitting Pressure Protection
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Solution Overview
Problem
In pipeline operations, orifice flowmeters face challenges in providing adequate protection against high pressure, and existing systems lack effective mechanisms for safe installation and removal of orifice plates while maintaining pressure regulation and preventing fluid escape.
Innovation Solution
A multi-double block and bleed system with four blocking valves and three vent valves is implemented, allowing for controlled fluid transfer and pressure management during orifice plate installation and removal, ensuring double block and bleed protection throughout the process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single blocking valve is used in the orifice plate transfer passage, then the device complexity is reduced, but the pressure protection and fluid containment reliability are insufficient
Solution Approach 1:
The single blocking valve is segmented into multiple blocking valves (first blocking valve, second blocking valve, third blocking valve, fourth blocking valve) arranged in series along the orifice plate transfer passage. Each valve provides an independent blocking function, creating multiple barriers that enhance pressure protection and fluid containment reliability while maintaining manageable system complexity through modular arrangement.
2Reliability
If multiple blocking valves are added to enhance pressure protection, then the reliability improves, but the device complexity increases
Solution Approach 1:
Vent valves are introduced as intermediary components between the blocking valves. These vent valves provide pressure equalization and fluid drainage functions, mediating the pressure differences that would otherwise require even more blocking valves to manage safely. The vent valves simplify the overall system by handling pressure management separately from the blocking function.
3Reliability
If blocking valves are closed to prevent fluid escape, then the pressure protection improves, but the ability to perform maintenance operations deteriorates
Solution Approach 1:
The vent valves are opened before closing the blocking valves to perform preliminary pressure equalization. This preliminary action removes pressure differentials that would make subsequent maintenance operations difficult or dangerous, allowing blocking valves to be closed safely while maintaining ease of orifice plate removal and installation.
4Ease of operation
If vent valves are opened to equalize pressure, then the ease of operation improves, but the risk of fluid escape increases
Solution Approach 1:
Blocking valves are positioned and closed before opening vent valves to perform preliminary containment. This preliminary anti-action establishes pressure barriers that prevent fluid escape during the subsequent venting operation, allowing safe pressure equalization without exposing the system to harmful fluid release.
Data Source
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AI summary
A system and method for providing a multi-double block and bleed configuration in an orifice fitting to provide an additional barrier of protection between the pressurized flow stream and the environment outside the flowmeter. The multi-double block and bleed system includes a first pair of blocking valves located below a second pair of blocking valves. The multi-double block and bleed system further includes a first vent valve positioned between blocking valves of the first pair blocking valves, a second vent valve positioned between blocking valves of the second pair of blocking valves, and a third vent valve positioned between the first and second pairs of blocking valves. The pairs of blocking valves and the vent valves are arranged to provide double block and bleed during all phases of orifice plate installation and removal.