Multistage Restriction Orifice Assemblies
Globe United designs Multistage Restriction Orifice assemblies for fixed pressure reduction duties where distributing the total pressure drop across several engineered stages can reduce hydraulic, acoustic and mechanical risk. The assembly has no moving parts and is configured around the specified process fluid, flow cases, pressure profile, temperature, piping interface and project requirements.
How a Multistage Restriction Orifice Works
Several restriction stages are arranged in series within an engineered spool assembly. Each stage creates part of the required pressure drop, followed by a recovery section before the next stage. For liquid service, stage sizing is reviewed against local vapour pressure and cavitation risk. For gas and steam service, the review considers choked flow, velocity, noise and vibration at each stage.
Available Configurations
- Flanged spool assemblies for the specified pressure class, facing and gasket arrangement
- Butt-weld spool assemblies for the approved piping material and welding procedure
- Multiple engineered restriction stages within one assembly
- Materials selected for pressure, temperature, corrosion, erosion and sour-service requirements
- Project-specific stage arrangement, bore sizes, spacing and pressure-boundary interfaces
- Calculation summary, general arrangement drawing and quality documentation as required
Applications
Multistage Restriction Orifices are considered for high differential pressure duties in oil and gas production, pipelines and terminals, refining and petrochemical facilities, chemical injection systems, boiler feedwater and condensate service, pump minimum-flow lines, industrial water systems and process letdown applications.
Engineering Information Required
A complete technical review requires minimum, normal and maximum flow cases, upstream and downstream pressure, operating and design temperature, fluid composition and phase, density, viscosity and vapour pressure for liquids, or molecular weight and compressibility information for gases. Pipe size, schedule, internal diameter, flange or weld-end details, materials, corrosion allowance, installation length, piping code, noise limits and project documentation requirements are also needed.
Installation and Commissioning
Install the assembly in the flow direction shown on the nameplate and approved drawing. Adjacent piping must be aligned and independently supported so the assembly is not used to correct pipe misalignment. During commissioning, pressurise the line gradually and check for leakage, abnormal differential pressure, noise and vibration. Use the project-specific drawings and the Globe United installation, operation and maintenance manual for the supplied unit.
Why Use Multiple Restriction Stages?
A single restriction can create an unacceptable local pressure drop, velocity, noise, vibration, cavitation or erosion risk. A correctly engineered multistage arrangement distributes the pressure reduction and provides a fixed restriction path matched to the stated operating cases.
Frequently Asked Questions
Is a Multistage Restriction Orifice a flowmeter?
No. Its primary purpose is engineered fixed pressure reduction. Flow measurement requirements must be reviewed separately.
How many stages are required?
The number of stages is determined from the required pressure reduction, fluid properties, flow cases, hydraulic limits, noise criteria and available installation envelope.
Can the assembly be used for liquids, gases and steam?
Yes, subject to a complete engineering review for the specific fluid, operating conditions and applicable project standards.
Contact Globe United with the process data and piping requirements for a Multistage Restriction Orifice quotation.
