How to Match a Pipe Flange with the Right Flange Adaptor Size

Key Components of Pipe Flange and Flange Adaptor Connections

Flange Types and Their Functional Roles

In piping systems, flanges are critical for joining pipes, valves, and other equipment. The most common types include:

• Weld Neck: Ideal for high pressure applications due to its tapered hub and butt welded connection.
• Slip On: Easier to install, suitable for low pressure systems.
• Socket Weld: Common in small bore piping, providing good strength and leakage integrity.
• Threaded: Used without welding, typically in low pressure applications or where welding isn’t feasible.

Equally important is the flange face type. Raised Face (RF), Flat Face (FF), and Ring Type Joint (RTJ) designs all influence sealing performance. RTJ flanges are used in high pressure environments and require specific adaptors that match their grooved sealing surfaces. Compatibility between flange face and adaptor sealing surfaces must be confirmed before selection.

Essential Features of Flange Adaptors

Adaptateurs de bride serve a key function — they connect dissimilar piping materials or components, such as joining polyethylene (PE) pipes to metal valves or meters. The product is used to connect PE pipe with metal pipe or valve, flowmeter, pressure gauge and other auxiliary equipment.

Material selection is central to durability. Common materials include ductile iron, carbon steel, stainless steel, and epoxy coated versions for corrosion resistance. Adaptors for aggressive environments may also feature fusion bonded epoxy or hot dip galvanization.

Compatibility is not just about size — it also depends on the piping material. For example, adaptors for PVC pipes differ from those for ductile iron or steel pipes in terms of clamping mechanisms and sealing rings.

The sealing method adopts socket type, and the dovetail groove design of sealing rubber ring has very good sealing performance, which can meet the sealing pressure of 2.5MPa at most.

Measuring Pipe Flanges Accurately for Adaptor Matching

Tools Required for Precise Measurement

Precision begins with the right tools:

• Vernier calipers for measuring flange OD and bolt hole diameter.
• Steel tape measures for larger dimensions like bolt circle diameter (BCD).
• Thread pitch gauges when dealing with threaded flanges.

Tools should be calibrated regularly. A simple misalignment can lead to mismatched adaptors or gasket failures.

Measuring the Outside Diameter (OD) of the Flange

OD is fundamental when classifying flange size. It’s measured across the widest part of the flange face. ANSI flange dimensions standardize these values. For instance, a 4-inch Class 150 flange typically has an OD of 9 inches (229 mm).

Determining the Bolt Circle Diameter (BCD)

BCD is the distance between centers of opposite bolt holes. To measure it:

1. Identify two opposing bolt holes.
2. Measure from center to center using a caliper or tape.

Mismatched BCD results in improper bolt alignment — a frequent cause of leaks when adaptors are installed.

Counting Bolt Holes and Measuring Their Diameter

ANSI flanges follow standard bolt patterns — a 6-inch Class 150 flange has 8 bolt holes of 0.75-inch diameter. Ensure tolerance is within ±0.03 inches to avoid forced fitting or misalignment during installation.

Measuring the Inner Diameter (Bore) of the Flange

The bore must match the pipe’s outer diameter for a tight fit. This is especially critical when adaptors must slide over the pipe end before being bolted. For lined or coated pipes, consider additional thickness when selecting adaptor size.

Identifying the Flange Face Type and Thickness

Face type determines gasket selection and affects sealing. Raised Face flanges require compression gaskets; Flat Face uses full face gaskets. Thickness influences torque settings — thicker flanges often demand higher torque to achieve proper seal compression.

Interpreting ANSI Flange Dimensions for Adaptor Selection

Overview of ASME B16.5 Standards for Steel Pipe Flanges

ASME B16.5 covers flange sizes from ½ inch to 24 inches across pressure classes 150 to 2500. Each size pressure combination has specific OD, BCD, bolt hole count, and thickness — all critical when selecting a matching flange adaptor.

Metric vs. Imperial Measurement Considerations

Global projects often mix metric and imperial systems. A common mistake is rounding dimensions during conversion, leading to poor fits. In such cases, custom adaptors may be necessary unless standard ANSI compatible options are available.

Ensuring Proper Fit Between Flange and Adaptor Components

Alignment Tolerances and Gasket Compatibility

Perfect bolt pattern alignment is essential to prevent leaks. Even a slight offset can shear gasket material or prevent uniform compression. Gasket material should match both the adaptor surface and process fluid — EPDM for water, PTFE for chemicals.

Material Compatibility Between Pipe, Flange, and Adaptor

Mixing metals like stainless steel with carbon steel can cause galvanic corrosion over time. Best practice pairs similar materials or uses dielectric insulators when dissimilar metals must be connected.

In water systems, ductile iron flanges often pair with PE pipe adaptors using EPDM gaskets. In oil lines, carbon steel with nitrile rubber seals is typical.

Practical Tips for Technicians During Installation Planning

Common Pitfalls to Avoid When Sizing Adaptors

• Misidentifying BCD as OD.
• Ignoring flange face type.
• Using old flanges with corroded surfaces without resurfacing them.

Each of these missteps can lead to failed connections or costly rework.

Field Verification Techniques Before Final Assembly

Templates made from previous successful installations help validate dimensions quickly on site. Digital measurement tools offer added accuracy. Trial fitting before installing gaskets reduces risk of misalignment during final tightening.

The Role of Conflex in Industrial Piping Solutions

Application Scenarios Where Conflex Adaptors Are Utilized

Conflit offers versatile flange adaptor solutions across sectors:

• Water distribution networks often rely on Conflex adaptors for connecting PE mains to control valves.
• Oil pipeline maintenance teams use them to retrofit aging steel lines without requiring full system replacement.

The product is used to connect PE pipe with metal pipe or valve, flowmeter, pressure gauge and other auxiliary equipment.

These adaptors are integrated into preventive maintenance schedules where quick disassembly and resealing are required.

How Conflex Supports Accurate Sizing with Technical Resources

Conflex provides detailed sizing charts aligned with ANSI flange dimensions. These reference guides simplify selection during planning stages.

In complex installations, Conflex’s engineering support assists technicians with custom adaptor configurations based on field measurements and system conditions.

FAQ

Q1: What is BCD in a pipe flange?

A: Bolt Circle Diameter (BCD) refers to the distance between centers of two opposite bolt holes on a flange.

Q2: Can I use one adaptor across different flange face types?

A: No, flange adaptors must match the flange face type (e.g., RF, FF) to ensure proper sealing.

Q3: How do I measure flange thickness accurately?

A: Use a caliper from the rear side of the flange face to the back edge; don’t include raised face height unless specified.

Q4: What material works best for water pipelines?

A: Ductile iron with EPDM gaskets is commonly used in water supply systems due to corrosion resistance and flexibility.

Q5: Does Conflex offer adaptors for lined pipes?

A: Yes, Conflex adaptors can accommodate adjustments for pipe linings or coatings where required.