ASME B16.36 Orifice Flanges

Super Industries
“Global Manufacturer of Heavy & Custom Engineered Fasteners for Oil & Gas, Power & EPC Contractors.”

1. Industry Context & System Relevance

Role in Industrial Piping Systems

ASME B16.36 Orifice Flanges are specialized piping components designed to facilitate accurate flow measurement using the differential pressure (DP) principle. Unlike standard flanges, these are engineered specifically to integrate with orifice plate assemblies, forming a complete flow measurement flange system.

Their function is not merely mechanical joining — they act as measurement interfaces within pressurized pipelines.

Functional Purpose in Flow Measurement

In industrial process systems, particularly in hydrocarbons and utilities, flow measurement must be:

• Repeatable
• Calibratable
• Standardized
• Compatible with instrumentation

Orifice flanges provide this by enabling:

• Installation of an orifice plate inside the pipeline
• Measurement of pressure differential across the restriction
• Transmission of pressure signals to DP transmitters

System Integration Architecture

A typical orifice flange installation includes:

• Upstream flange with pressure tap
• Downstream flange with pressure tap
• Orifice plate sandwiched between flanges
• Gaskets ensuring pressure-tight sealing
• Impulse lines connected to pressure transmitters

This assembly forms a primary flow measurement element in accordance with flow measurement standards.

Applications Across Industries

Orifice flange systems are deployed in:

Oil & Gas Pipelines

• Custody transfer metering
• Gas flow measurement
• Crude oil transport monitoring

Refineries

• Process stream monitoring
• Fuel gas measurement
• Distillation unit flow control

Petrochemical Plants

• Chemical dosing control
• Reactor feed monitoring

Power Plants

• Steam flow measurement
• Boiler feedwater monitoring

LNG Terminals

• Cryogenic fluid measurement
• Vapor flow tracking

Offshore Platforms

• Compact metering solutions
• High-pressure flow systems

General Process Industries

• Water systems
• Utility distribution networks

Why Orifice Flanges Instead of Standard Flanges

Standard flanges lack the following essential features:

Requirement	Standard Flanges	Orifice Flanges
Pressure tapping	Not available	Integrated
Orifice plate support	Not designed	Designed specifically
Measurement capability	None	Full DP measurement
Maintenance access	Limited	Jack screws provided
Instrumentation integration	External modification required	Built-in

Thus, ASME B16.36 Orifice Flanges eliminate the need for external drilling, ensuring:

• Dimensional accuracy
• Repeatable measurement geometry
• Reduced installation errors

Importance in Measurement Accuracy

Flow accuracy depends heavily on:

• Precise positioning of pressure taps
• Smooth bore alignment
• Consistent restriction geometry

Orifice flanges ensure:

• Factory-controlled tap location
• Concentric alignment with pipe bore
• Compliance with flow measurement standards

This directly impacts:

• Measurement uncertainty
• Calibration reliability
• Regulatory compliance

Maintenance & Operational Advantages

Orifice flanges are equipped with jack screws, which serve a critical function:

• Facilitate separation of flanges
• Allow safe removal of the orifice plate
• Enable inspection and replacement without pipeline damage

This is essential in systems where:

• Periodic calibration is required
• Plate wear or erosion occurs
• Process conditions change

2. Technical Definition

Definition

ASME B16.36 Orifice Flanges are pressure-retaining flanges specifically designed to house orifice plates and enable differential pressure measurement, incorporating:

• Precisely machined pressure tap holes
• Integrated jack screws
• Controlled bore geometry
• Compatibility with standard flange dimensions

Core Design Characteristics

1. Pressure Tap Holes

Each flange includes:

• One or more radial pressure tapping points
• Threaded connections for impulse lines
• Accurate positioning relative to orifice plate

These taps are used to measure:

• Upstream pressure
• Downstream pressure

2. Tap Configurations

Common configurations include:

Flange Taps

• Located 1 inch from flange face (standard)
• Most widely used configuration

Corner Taps

• Located at plate faces
• Used in specific measurement standards

Custom Tap Configurations

• Based on ISO or project specifications

3. Jack Screws

Integrated threaded holes enable:

• Controlled flange separation
• Safe removal of orifice plate
• Prevention of flange damage

4. Bore Alignment

Critical requirement:

• Bore must align perfectly with pipe ID
• Concentricity tolerance must be tightly controlled

Misalignment leads to:

• Flow disturbances
• Measurement errors

5. Facing Types

Available as:

Raised Face (RF)

• General-purpose applications
• Suitable for most pressure classes

Ring Type Joint (RTJ)

• High-pressure systems
• Metal-to-metal sealing

6. Pressure Containment with Instrumentation Ports

Despite the presence of drilled taps:

• Structural integrity must be maintained
• Leak-proof sealing at tapping points is mandatory

Thread types typically include:

• NPT
• BSP (project-specific)

3. Engineering & Flow Measurement Principle

Fundamental Concept

Orifice flanges operate based on the differential pressure flow measurement principle, derived from fluid mechanics.

Working Mechanism

1. Fluid flows through a pipeline
2. Orifice plate introduces a restriction
3. Velocity increases at restriction
4. Static pressure decreases
5. Pressure difference (ΔP) is generated
6. ΔP is measured via flange taps
7. Flow rate is calculated

Governing Physics

Continuity Equation

Mass conservation:

   

Where:

• (Q) = flow rate
• (A) = cross-sectional area
• (V) = velocity

Bernoulli’s Principle

Energy conservation:

   

This explains:

• Pressure drop due to velocity increase
• Relationship between pressure and flow

Flow Rate Equation (Orifice Flow)

The volumetric flow rate is given by:

   

Where:

• (C_d) = discharge coefficient
• (A_o) = orifice area
• (\Delta P) = differential pressure
• (\rho) = fluid density
• (\beta) = ratio of orifice diameter to pipe diameter

Discharge Coefficient (Cd)

Accounts for:

• Non-ideal flow conditions
• Viscosity effects
• Edge sharpness

Typical range:

• 0.6 to 0.65 (depending on Reynolds number and geometry)

Flow vs Pressure Relationship

Key relationship:

   

Implication:

• Small measurement error in ΔP → amplified error in flow
• Requires precise tap positioning and calibration

Accuracy Considerations

Flow accuracy depends on:

• Proper installation
• Smooth upstream flow profile
• Correct plate geometry
• Accurate pressure measurement

Typical accuracy:

• ±0.5% to ±2% (depending on system design)

Limitations vs Other Flow Meters

Parameter	Orifice Flange System	Advanced Flow Meters
Accuracy	Moderate	High
Cost	Low	High
Maintenance	Moderate	Low
Pressure loss	High	Low
Simplicity	High	Moderate

Engineering Trade-Off

Orifice flange systems are preferred when:

• Standardization is required
• Cost control is critical
• Maintenance access is available
• High accuracy is not mission-critical

System Dependency on Flange Design

Measurement reliability is directly linked to:

• Tap hole precision
• Bore finish
• Plate centering
• Flange alignment

Thus, ASME B16.36 Orifice Flanges are not interchangeable with standard flanges in measurement applications.

4. Applicable Standards (ASME / ASTM / ISO / DIN)

Primary Governing Standard

ASME B16.36 — Orifice Flanges

This is the principal standard defining:

• Dimensional requirements for orifice flanges
• Pressure tap locations and configurations
• Pressure class ratings (Class 300 to 2500 typical coverage)
• Facing types (RF / RTJ)
• Bore alignment requirements

It ensures that ASME B16.36 Orifice Flanges are:

• Interchangeable across manufacturers
• Compatible with standard piping systems
• Suitable for differential pressure measurement

Related Dimensional Standard

ASME B16.5 — Pipe Flanges and Flanged Fittings

Provides:

• Bolt circle dimensions
• Flange outside diameter
• Thickness and pressure ratings
• Gasket seating details

Orifice flanges adopt these base dimensions while incorporating:

• Pressure taps
• Jack screw provisions

Flow Measurement Standards

ASME MFC-3M

Covers:

• Measurement of fluid flow in pipes using orifice plates
• Calculation methodologies
• Installation guidelines

ISO 5167

International standard governing:

• Orifice plate design
• Differential pressure measurement methods
• Flow calculation equations
• Accuracy requirements

This standard is critical for:

• Custody transfer systems
• International project compliance

Material Standards (ASTM)

Material selection for orifice flanges is governed by:

• ASTM A105 – Carbon steel forgings
• ASTM A350 LF2 – Low-temperature carbon steel
• ASTM A182 – Stainless and alloy steel forgings

These standards define:

• Chemical composition
• Mechanical properties
• Heat treatment conditions
• Testing requirements

Standards Mapping to Functional Requirements

Requirement	Governing Standard
Dimensional accuracy	ASME B16.36
Pressure rating	ASME B16.5
Flow calculation	ISO 5167 / ASME MFC-3M
Material integrity	ASTM standards
Inspection documentation	EN 10204

5. Material & Grade Options

Material selection directly affects:

• Corrosion resistance
• Pressure-temperature capability
• Mechanical strength
• Service life

Carbon Steel Grades

ASTM A105

• Most widely used forging material
• Suitable for ambient and moderate temperature service
• Good machinability
• Cost-effective for general applications

ASTM A350 LF2

• Designed for low-temperature applications
• Improved impact toughness
• Used in LNG and cryogenic systems

Stainless Steel Grades

ASTM A182 F304

• General corrosion resistance
• Suitable for water, steam, and mild chemicals

ASTM A182 F316

• Enhanced corrosion resistance due to molybdenum
• Suitable for chlorides and aggressive chemicals
• Preferred in offshore and marine environments

Alloy Steel Grades

ASTM A182 F11 / F22

• High-temperature service
• Improved creep resistance
• Used in power plants and refineries

Duplex & Super Duplex Stainless Steels

• High strength + corrosion resistance
• Resistant to stress corrosion cracking
• Used in offshore, subsea, and aggressive chemical environments

Material Comparison Table

Grade	Yield Strength (MPa)	Tensile Strength (MPa)	Temperature Range	Corrosion Resistance	Typical Application
A105	~250	485–620	-29°C to 425°C	Moderate	Oil & gas pipelines
A350 LF2	~250	485–620	-46°C and below	Moderate	LNG, low-temp service
F304	~205	515	Up to 870°C	Good	Water, chemicals
F316	~205	515	Up to 870°C	Excellent	Marine, chemical
F11	~275	415–585	Up to 540°C	Moderate	Power plants
F22	~415	585–760	Up to 600°C	Moderate	High-temp service
Duplex	~450	620–880	-50°C to 300°C	Very high	Offshore
Super Duplex	~550	750–950	-50°C to 300°C	ممتاز	Subsea, corrosive

6. Heat Treatment Information

Heat treatment is essential for:

• Mechanical property enhancement
• Residual stress relief
• Dimensional stability during machining

1. Normalizing

• Refines grain structure
• Improves uniformity
• Enhances strength

Used for:

• Carbon steel flanges

2. Quenching & Tempering

• Increases strength and hardness
• Improves toughness

Used for:

• Alloy steels (F11, F22)

3. Stress Relieving

• Reduces residual stresses after machining
• Prevents distortion during service

Critical for:

• Flanges with pressure taps (stress concentration zones)

4. Solution Annealing

• Dissolves carbides
• Restores corrosion resistance

Used for:

• Stainless steels
• Duplex grades

Impact of Heat Treatment

Property	Effect
Machinability	Improved
Dimensional stability	Enhanced
Crack resistance	Increased
Fatigue performance	Improved

7. Manufacturing Process

Manufacturing of ASME B16.36 Orifice Flanges requires high precision due to:

• Flow measurement sensitivity
• Tap alignment criticality

Step-by-Step Process

1. Raw Material Inspection

• Chemical analysis (spectrometry)
• Verification against ASTM standards
• Traceability marking

2. Forging

• Open-die or closed-die forging
• Grain flow aligned with stress direction
• Eliminates internal defects

3. Heat Treatment

• As per material grade
• Ensures required mechanical properties

4. Rough Machining

• OD turning
• Bore preparation
• Face leveling

5. CNC Machining

Critical stage involving:

• Precision bore machining
• Facing (RF / RTJ)
• Bolt hole drilling

Tolerance control is essential.

6. Bore Finishing

• Surface smoothness critical for flow
• Prevents turbulence and measurement error

7. Pressure Tap Hole Drilling (CRITICAL OPERATION)

This is the defining feature of orifice flanges:

• Radial drilling at exact specified distance
• Threading (NPT or BSP)
• Alignment verification

Tolerance errors can lead to:

• Incorrect ΔP measurement
• Flow inaccuracies

8. Jack Screw Threading

• Precision tapping for jack screws
• Ensures safe plate removal

9. Facing Machining

RF:

• Serrated finish for gasket seating

RTJ:

• Groove machining with tight tolerances

10. Final Inspection

• Dimensional checks
• Tap alignment verification
• Surface finish inspection

11. Marking & Traceability

Includes:

• Heat number
• Material grade
• Size and pressure class
• Manufacturer identification

8. Surface Finish Options

Surface finishing is selected based on:

• Corrosion environment
• Storage duration
• Project specifications

Common Surface Treatments

Anti-Rust Oil

• Temporary protection
• Used for short-term storage

Black Coating

• Oxide layer formation
• Moderate corrosion resistance

Zinc Plating

• Electroplated coating
• Improved corrosion resistance
• Suitable for mild environments

Hot-Dip Galvanizing

• Thick zinc coating
• Long-term outdoor protection

Passivation

• Removes free iron
• Enhances corrosion resistance of stainless steel

Surface Roughness & Gasket Compatibility

Facing Type	Surface Finish Requirement
RF	125–250 AARH serrated
RTJ	Smooth groove finish

Engineering Considerations

Surface finish affects:

• Gasket sealing performance
• Leak prevention
• Long-term reliability

A. Technical Dimension Tables (Representative — ASME B16.36 with B16.5 Integration)

Note: Dimensions are aligned with ASME B16.36 Orifice Flanges in conjunction with ASME B16.5 base flange geometry. Exact values may vary based on project specification, facing type, and tapping configuration.

Class 300 Orifice Flanges (Raised Face – RF)

NPS	OD (mm)	Thickness (mm)	Bore (mm)	Bolt Circle (mm)	Bolt Size	No. of Bolts	Tap Size	Jack Screws
2″	165	25	52.5	127	M16	8	1/2″ NPT	2
4″	254	32	102.3	190	M20	8	1/2″ NPT	2
6″	279	36	154.1	241	M22	12	1/2″ NPT	2
8″	343	41	202.7	298	M24	12	1/2″ NPT	2
10″	406	48	254.5	362	M27	16	1/2″ NPT	2
12″	483	51	303.2	432	M30	16	1/2″ NPT	2

Class 600 Orifice Flanges (Raised Face – RF)

NPS	OD (mm)	Thickness (mm)	Bore (mm)	Bolt Circle (mm)	Bolt Size	No. of Bolts	Tap Size	Jack Screws
2″	165	32	52.5	127	M16	8	1/2″ NPT	2
4″	273	38	102.3	190	M20	8	1/2″ NPT	2
6″	318	45	154.1	241	M22	12	1/2″ NPT	2
8″	381	51	202.7	298	M24	12	1/2″ NPT	2
10″	444	57	254.5	362	M30	16	1/2″ NPT	2
12″	521	64	303.2	432	M33	16	1/2″ NPT	2

Dimensional Engineering Considerations

• Bore tolerance: critical for flow profile stability
• Tap hole distance: typically 25.4 mm (1 inch) from flange face (flange taps)
• Concentricity: must align with pipe ID to prevent asymmetric flow

B. Pressure Rating Table (ASME B16.5 Reference)

Carbon Steel (A105) — Pressure vs Temperature

Class	38°C	100°C	200°C	300°C	400°C
150	19.6 bar	17.7	15.2	13.2	11.4
300	51.1 bar	46.6	40.0	34.7	30.2
600	102.1 bar	93.1	80.0	69.5	60.4
900	153.2 bar	139.7	120.0	104.2	90.6
1500	255.3 bar	232.8	200.0	173.7	151.0
2500	425.5 bar	388.0	333.0	289.4	251.5

Engineering Interpretation

• Pressure rating reduces with temperature increase
• Material grade affects allowable stress
• Orifice flanges must maintain integrity despite tap-induced stress concentration

C. Torque Chart

Based on carbon steel bolts, standard lubrication conditions.

Bolt Size	Torque (Nm) – Lubricated	Torque (Nm) – Dry
M16	120	160
M20	240	320
M22	320	420
M24	420	560
M27	620	820
M30	850	1100
M33	1150	1500

Torque Engineering Notes

• Lubrication reduces friction → lower torque required
• Over-tightening can distort orifice plate alignment
• Uniform tightening sequence is mandatory

D. Flow Calculation Guide

Orifice Flow Equation

   

Parameter Definitions

• (Q) = Volumetric flow rate
• (C_d) = Discharge coefficient
• (A_o) = Orifice area
• (\Delta P) = Differential pressure
• (\rho) = Fluid density
• (\beta) = Diameter ratio

Sample Calculation

Given:

• Pipe diameter = 100 mm
• Orifice diameter = 50 mm → β = 0.5
• ΔP = 10,000 Pa
• Density = 1000 kg/m³
• Cd = 0.62

Step 1: Orifice Area

   

Step 2: Flow Rate

   

   

   

Engineering Insight

• Flow rate increases with √ΔP
• Higher β ratio reduces pressure drop but affects accuracy
• Cd must be calibrated based on Reynolds number

E. Differential Pressure vs Flow Rate Table

ΔP (Pa)	Flow Rate (m³/s)
2,500	0.0028
5,000	0.0040
10,000	0.0056
20,000	0.0080
40,000	0.0113

Interpretation

• Non-linear relationship
• Doubling ΔP does not double flow
• Requires calibrated instrumentation

F. Mechanical Property Table

Material	Yield Strength (MPa)	Tensile Strength (MPa)	Hardness (HB)	Impact (J)
A105	250	485–620	120–180	27
LF2	250	485–620	120–180	40 (low temp)
F304	205	515	150–200	60
F316	205	515	150–200	60
F22	415	585–760	170–220	30
Duplex	450	620–880	250	80

G. Corrosion Resistance Table

Environment	Carbon Steel	SS 304	SS 316	Duplex	Super Duplex
Marine	Poor	Moderate	Good	Excellent	Superior
Acidic	Poor	Moderate	Good	Excellent	Superior
Hydrocarbon	Good	Excellent	Excellent	Excellent	Excellent
Humid	Moderate	Good	Excellent	Excellent	Superior

9. Inspection & Quality Control Methods

Material Verification

PMI (Positive Material Identification)

• Confirms chemical composition
• Ensures correct alloy grade

Non-Destructive Testing (NDT)

Ultrasonic Testing (UT)

• Detects internal defects
• Ensures forging integrity

Magnetic Particle Inspection (MPI)

• Surface crack detection (ferromagnetic materials)

Dye Penetrant Inspection (DPI)

• Detects surface discontinuities
• Used for stainless steel

Dimensional Inspection

Critical checks:

• Bore diameter
• Flange thickness
• Bolt hole alignment
• Facing geometry

Tap Alignment Verification (CRITICAL)

• Position tolerance must meet ASME B16.36
• Angular deviation must be minimal
• Ensures accurate ΔP measurement

Pressure Tap Testing

• Leak testing at tapping points
• Thread integrity verification
• Ensures no pressure loss

Hydrostatic / Pressure Testing (if specified)

• Confirms pressure containment capability

Documentation & Certification

EN 10204 Certification

• 3.1 – Manufacturer test certificate
• 3.2 – Third-party verified certificate

Third-Party Inspection

Typically performed by:

• Independent inspection agencies
• Client-appointed inspectors
• EPC project QA/QC teams

Inspection Traceability

Each flange is traceable via:

• Heat number
• Batch number
• Inspection records
• Material certificates

10. Industries Served

ASME B16.36 Orifice Flanges are deployed in systems where repeatable, standard-compliant differential pressure flow measurement is required under varying pressure, temperature, and fluid conditions.

Oil & Gas (Upstream, Midstream, Downstream)

Functional Roles:

• Custody transfer metering (gas and liquid hydrocarbons)
• Wellhead flow monitoring
• Pipeline transmission measurement

Engineering Considerations:

• High-pressure classes (600–2500)
• Sour service compatibility (material selection critical)
• Compliance with ISO 5167 and custody transfer standards

Refineries

Applications:

• Process stream flow control
• Fuel gas measurement
• Crude distillation unit monitoring

System Requirements:

• High-temperature capability
• Resistance to corrosive hydrocarbons
• Integration with distributed control systems (DCS)

Petrochemical Plants

Applications:

• Reactor feed measurement
• Chemical dosing systems
• Utility distribution

Key Requirements:

• Chemical compatibility (SS316 / Duplex)
• Measurement stability under varying loads

Power Generation (Thermal & Nuclear Auxiliaries)

Applications:

• Steam flow measurement
• Boiler feedwater monitoring
• Condensate systems

Engineering Requirements:

• High-temperature alloy steels (F11 / F22)
• Resistance to thermal cycling
• Long-term dimensional stability

LNG & Cryogenic Systems

Applications:

• LNG transfer lines
• Vapor flow measurement
• Cryogenic storage systems

Material Requirements:

• Low-temperature toughness (A350 LF2, stainless steel)
• Impact-tested materials

Offshore & Subsea Installations

Applications:

• Platform flow monitoring
• Subsea pipeline systems

Engineering Challenges:

• Corrosion resistance (duplex / super duplex)
• Compact installation constraints
• Maintenance accessibility

Water, Utilities & Process Industries

Applications:

• Water distribution systems
• Industrial utilities
• Effluent treatment plants

Requirements:

• Cost-effective material selection
• Moderate pressure classes
• Ease of maintenance

11. Export Capability & Global Supply

Super Industries operates as a manufacturer and global exporter of ASME B16.36 Orifice Flanges, aligned with EPC project supply requirements.

Global Supply Regions

Typical export destinations include:

• Middle East (UAE, Saudi Arabia, Qatar, Kuwait)
• Southeast Asia (Singapore, Indonesia, Malaysia)
• Europe (Germany, Italy, Netherlands)
• Africa (Nigeria, Egypt)
• North America (project-specific supply)

Export Packaging Standards

Packaging is designed to ensure:

• Mechanical protection
• Corrosion prevention
• Traceability retention

Methods include:

• Wooden boxes (ISPM 15 compliant)
• Palletized loads
• Individual flange wrapping with VCI material
• End protection for facing surfaces

Documentation Package

Each shipment can be supplied with:

• Commercial invoice
• Packing list
• Material Test Certificates (EN 10204 3.1 / 3.2)
• PMI reports
• NDT reports (UT, MPI, DPI)
• Dimensional inspection reports
• Heat treatment records
• Third-party inspection release notes

Logistics & Project Handling

• Batch-wise supply for large EPC projects
• Marking aligned with project tagging systems
• Coordination with freight forwarders
• Break-bulk and container shipments

Project Supply Capability

Supports:

• EPC contractors
• Process licensors
• Engineering consultants

Capabilities include:

• Bulk production for pipeline packages
• Custom engineering for project-specific requirements
• Integration with instrumentation vendors

12. Procurement & Installation Engineering View

1. Orifice Plate Installation

Correct installation sequence:

1. Verify flange orientation (tap alignment)
2. Insert gasket on upstream flange
3. Position orifice plate (correct flow direction marking)
4. Insert downstream gasket
5. Align flanges concentrically
6. Install bolts and hand-tighten

2. Alignment with Pressure Taps

• Taps must be located correctly (top/bottom or side depending on service)
• Misalignment results in incorrect ΔP measurement
• Horizontal vs vertical installation must be considered

3. Gasket Selection

Depends on:

• Pressure class
• Temperature
• Fluid type

Common types:

• Spiral wound gaskets (RF)
• Ring type joint (RTJ) gaskets

4. Bolt Tightening Sequence

• Cross-pattern tightening (star sequence)
• Incremental torque application
• Final torque as per torque chart (Part 3)

Engineering objective:

• Uniform gasket compression
• Avoid flange distortion

5. Instrument Connection

• Impulse lines connected to tap holes
• Isolation valves installed
• Condensate pots (for steam service)
• Proper slope for impulse lines

6. Commissioning & Calibration

• Zero calibration of DP transmitter
• Leak testing at tap connections
• Verification against known flow conditions

7. Maintenance Using Jack Screws

Procedure:

1. Depressurize system
2. Loosen flange bolts
3. Engage jack screws evenly
4. Separate flanges gradually
5. Remove orifice plate

Advantages:

• Prevents flange face damage
• Controlled separation
• Safe maintenance operation

8. Calibration & Accuracy Considerations

Accuracy depends on:

• Plate edge sharpness
• Tap cleanliness
• Instrument calibration
• Flow profile (upstream straight length)

13. Custom Engineering Capabilities

1. Non-Standard Tap Configurations

• Corner taps
• Radius taps
• Multi-tap configurations

2. High-Pressure Orifice Flanges

• Class 1500 / 2500
• Reinforced designs
• RTJ facing customization

3. Special Bore Tolerances

• Tight bore concentricity
• Custom β ratio compatibility

4. RTJ Customization

• Groove profiling
• Ring number compatibility

5. Instrument-Integrated Flange Systems

• Pre-mounted impulse connections
• Integrated manifolds (project-specific)

14. Engineering Summary & Technical Conclusion

ASME B16.36 Orifice Flanges function as precision-engineered measurement interfaces rather than conventional piping connectors.

Their performance directly influences:

• Flow measurement accuracy
• Process control stability
• Custody transfer reliability

Key Engineering Characteristics

• Integrated pressure tapping system
• Controlled bore geometry
• Compatibility with international flow standards
• Structural integrity under pressure and thermal loads

Design & Manufacturing Criticality

Reliable performance requires:

• Accurate tap positioning
• High-quality forging
• Controlled machining tolerances
• Verified inspection procedures

System-Level Importance

In a differential pressure flow system:

• Orifice plate = primary restriction element
• Orifice flange = measurement interface
• Instrumentation = data acquisition

Failure in flange design affects the entire system.

Procurement Evaluation Perspective

From an EPC and consultant standpoint, acceptable supply must demonstrate:

• Compliance with ASME B16.36 and related standards
• Documented material traceability
• Verified tap alignment and dimensional accuracy
• Complete inspection and certification records

Final Engineering Position

A properly designed and manufactured ASME B16.36 Orifice Flange system ensures:

• Repeatable and standard-compliant flow measurement
• Mechanical reliability under operating conditions
• Integration readiness with instrumentation systems