Choke Assemblies
A choke assembly is a precision flow restriction device designed to create a controlled pressure drop in a gas or liquid stream. Unlike a simple orifice, a choke assembly typically combines the restriction element with a body, connections, and often an adjustment mechanism — allowing the pressure drop and flow rate to be set and, in some configurations, adjusted in service.
BelGAS choke assemblies are known in the industry as standard choke assemblies — products with a design heritage and engineering experience that has set the benchmark for decades.
What Choke Assemblies Do
In upstream oil and gas service, choke assemblies perform two main functions:
1. Wellhead pressure reduction — reducing flowing wellhead pressure to the operating pressure of the production system (separator inlet or flowline pressure). This is the same function as a choke valve, but in a precision engineered assembly format suited to instrumentation-grade service.
2. Process gas pressure control — controlling the pressure and flow rate of gas streams within processing facilities, metering stations, and SCADA-monitored systems.
The BelGAS choke assembly is particularly suited to applications where the choke must be precisely sized, reliably maintained, and integrated with other instrumentation components.
BelGAS Choke Assemblies
BelGAS is described by Marsh Bellofram as “known for industry-standard choke assemblies, with a reputation built on engineering and hands-on design experience that has set the standard for decades.”
BelGAS choke assemblies are available for:
- Fixed bean (orifice) configurations — sized for a specific pressure drop at design flow rate
- Adjustable configurations — allowing field adjustment of the pressure drop without disassembly
- A range of body materials — carbon steel, stainless steel, and CRA options for sour service
- Multiple end connection styles — threaded and flanged
Contact Proxima for BelGAS choke assembly selection based on your upstream pressure, downstream pressure, flow rate, and fluid composition.
Applications
- Wellhead gas pressure reduction to separator inlet pressure
- Gas meter run inlet pressure regulation
- SCADA station gas pressure control
- Fuel gas pressure reduction to engine and burner supply pressure
- Test separator pressure control
- Gas sampling system pressure reduction
Key Specifications
| Parameter | Details |
|---|---|
| — | — |
| Configuration | Fixed bean or adjustable |
| Body materials | Carbon steel, stainless steel, CRA options |
| End connections | Threaded, flanged |
| Sour service | NACE MR0175-compliant options |
| Flow media | Gas, liquid |
| Sizing | Based on upstream/downstream pressure and flow rate |
Suppliers
| Supplier | Product | Notes |
|---|---|---|
| — | — | — |
| BelGAS (Marsh Bellofram Group) | Choke assemblies | Industry-standard design, USA-manufactured |
*Note: WNS Lowery Series 20 Choke Valve (page 2.4.1) covers lower-pressure wellhead choke applications. BelGAS choke assemblies cover precision process and higher-pressure applications.*
Why Source Through Proxima
Proxima supplies BelGAS choke assemblies with full sizing support. Provide your upstream pressure, downstream pressure, gas flow rate, and fluid composition — we will specify the correct bean size and assembly configuration.
Frequently Asked Questions
Q: What data do I need to size a choke assembly?
Upstream pressure, downstream pressure, gas flow rate (MMSCFD or Nm³/day), gas composition (specific gravity or molecular weight), and flowing temperature. Proxima engineers calculate the required bean size from this data.
Q: What is the difference between a fixed bean and an adjustable choke?
A fixed bean is a precision orifice of a specific size — it cannot be changed without disassembly. An adjustable choke allows the flow area to be changed from outside the assembly during operation. Fixed beans are more precise and lower cost; adjustable chokes allow flow management without shutting in the well or isolating the system.
Q: Are BelGAS choke assemblies available for sour service?
Yes. NACE MR0175-compliant wetted materials are available for H₂S service. Specify H₂S concentration and partial pressure when requesting a quote.
Q: How does a choke assembly differ from a pressure regulator?
A pressure regulator is a self-operated control device that maintains constant downstream pressure regardless of flow variation — it adjusts automatically. A choke assembly is a fixed or manually adjusted restriction — it does not automatically compensate for changes in flow or upstream pressure. Chokes are used where a fixed pressure drop is acceptable; regulators where constant pressure is required.
