PTC6 Flow Nozzle

ASME PTC-6 Flow Nozzle


± 0.25% Always Calibrated
Highest Accuracy / Repeatability

  • Line Size: 4” to 28” 
  • Head Loss % of Differential: 60% to 85% beta dependent (18% to 25% with optional outlet diffuser cone)
  • Recommended Application, THROAT Reynolds Number: Greater than 500,000

ASME PTC-6 Flow Nozzle for Highest-Accuracy Steam Turbine Performance Testing

The ASME PTC-6 flow nozzle is a specialized differential pressure device designed to deliver the highest accuracy and repeatability required for steam turbine efficiency testing under the ASME PTC-6 Performance Test Code. Primary Flow Signal supplies PTC-6 nozzles as complete assemblies, including integrated upstream and downstream pipe spools, a flow conditioner, and an optional nozzle outlet diffuser cone to significantly reduce permanent pressure loss.

PFS PTC-6 flow nozzles are always calibrated and guaranteed to meet the stringent laboratory calibration criteria necessary for turbine performance testing. Because PTC-6 applications carry high risk if calibration requirements are not met, PFS calibrates each unit independently at a leading high Reynolds number facility and provides the documentation needed to support defensible test results. PFS also specializes in the refurbishment of nozzle runs for existing installations.

Key Benefits & Features:

PTC6 Flow Nozzle
  • Always Calibrated, High Accuracy: Typical uncertainty of plus or minus 0.25%, supporting demanding performance test requirements.
  • Best-in-Class Repeatability: Repeatability better than ±0.1% for stable, defensible measurement.
  • PTC-6 Compliance: Designed specifically to meet ASME PTC-6 requirements for turbine efficiency testing.
  • Complete, Jobsite-Ready Assembly: Supplied with integrated pipe spools and flow conditioner for consistent, standards-aligned performance.
  • Durable, Low Maintenance Design: No moving parts and lower susceptibility to erosion support long service life.
  • High Velocity Capability: Well-suited for high velocity applications and high pressure or high temperature services.
  • Refurbishment Expertise: PFS offers refurbishment services for nozzle runs to extend asset life and restore performance.

PTC-6 Flow Nozzles are primarily used for steam and water flow measurement in power generation environments, especially where turbine performance testing and high-accuracy efficiency verification are required.

ASME PTC-6 Flow Nozzle Specifications

Line Size
4” to 28” (not limited to)
Service Functional Limits
Clear liquids, gas and steam, typically hot water
Basic Accuracy (% of Total)
± 0.25% (always calibrated)
Repeatability
> ± 0.1%
Turndown Ratio
10:1, 20:1, 50:1
Greater can be achieved depending on the specific model and design of the meter as well as the type of secondary instrumentation system utilized
Recommended Application, THROAT Reynolds Number
Greater than 500,000
Required Straight Piping
20D Upstream / 10D Downstream
Beta Range
0.25 to 0.50
Head Loss % of Differential
60% to 85% beta dependent (18-25% with optional outlet diffuser cone)
Install Types
Mounts in any position
Useful Service Life
Medium to long

Construction Standards
• ASME Section I
• ASME B31.1 Power Piping
• ASME B31.3 Process Piping
Design Standards
• ASME PTC-6

ASME PTC-6 Flow Nozzle Model Types

Model Types


  • PTFFR – PTC-6, Flanged Nozzle, Flanged Ends, Run
  • PTFWR – PTC-6, Flanged Nozzle, Welded Ends, Run
  • PTWFR – PTC-6, Welded Nozzle, Flanged Ends, Run
  • PTWWR – PTC-6, Welded Nozzle, Welded Ends, Run

ASME PTC-6 Flow Nozzle Materials

Typical material selections for standard applications:


  • Carbon Steel 
  • 304/316 Stainless Steel 
  • Chrome Moly

Other options for material selection (not limited to):


  • Aluminum
  • Zirconium
  • Hastelloy
  • Monel
  • Duplex SS 
  • Titanium 
  • Tantalum 
  • 321 SS

ASME PTC-6 Flow Nozzle Certifications

PFS is a contributor to various international standards committees, fully supporting our staff’s memberships to these commissions.

Individual products follow relevant industry regulations, including requirements specific to the oil and gas, water/wastewater, and power generation industries.

PFS maintains the following certifications, standards & compliances:

  • ISO 9001
  • AGA
  • ASME S & U
  • API
  • ANSI
  • European Pressure Equipment Directive (PED)

Applications

Power Generation & Turbine Testing

ASME PTC-6 flow nozzles are primarily used in power plants for steam and water flow measurement tied to steam turbine performance testing. Their always-calibrated accuracy supports defensible efficiency verification and performance reporting.

Industrial Commissioning & Performance Validation

During new installs, retrofits, and major turbine upgrades, PTC-6 flow nozzles provide repeatable flow data used to validate performance and reduce uncertainty. Complete nozzle run assemblies support consistent installation in high-value test setups.

Industrial Efficiency Verification & Test Loops

PTC-6 flow nozzles are used when heat rate and efficiency data must be measured with high confidence, including benchmarking, audits, and third-party verification. They are also a strong fit for controlled steam and hot water test loops where precision and repeatability are required.

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