複雑なパイプライン システムの場合, 特に油の中では & ガス, 石油化学, 水処理, そして発電所, engineers often face the challenge of connecting pipes of different diameters. そのような場合には, standard flanges cannot provide the necessary transition without creating turbulence, 位置ずれ, or flow obstruction. そこです eccentric flanges come into play. These specially designed flanges offer a streamlined and practical solution for joining mismatched pipe sizes while maintaining flow efficiency and structural integrity.

This article explains what eccentric flanges are, 彼らはどのように働くのか, where they are used, and the benefits they offer. If you’re in the business of process piping or industrial systems, understanding the role of eccentric flanges is essential for maintaining performance and safety.

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1. What Is an Eccentric Flange?

アン eccentric flange is a type of pipe flange that features an offset bore—meaning the center of the bore is not aligned with the center of the flange face. This design allows the flange to connect two pipes of unequal sizes while keeping one side of the pipe system flat or aligned.

Eccentric flanges are often used with eccentric reducers, allowing smooth transitions between pipe diameters without interrupting flow or creating pockets where debris can collect.

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2. How Eccentric Flanges Work

In a piping system, when a smaller pipe needs to connect to a larger one, simply using a standard reducer and flange may result in a step or gap at the bottom or top of the pipe run. This can lead to:

• Flow turbulence

• Air pockets or cavitation

• Accumulation of sediment or chemicals

• Drainage issues

Eccentric flanges solve this by keeping the bottom (or top) level of the two pipes aligned, depending on the flow requirement. The result is a sloped transition, which promotes uninterrupted fluid movement—critical in horizontal lines and slurry or chemical systems.

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3. Key Features of Eccentric Flanges

• Offset centerline for bore alignment

• Custom-made to match specific pipe sizes and pressure classes

• Can be supplied in ウェルドネック, スリッポン, または 盲目 configurations

• Compatible with both standard and non-standard reducers

• Available in a wide range of materials and finishes

ササフランジ provides eccentric flanges in carbon steel, ステンレス鋼, 合金鋼, and exotic materials, tailored to your system’s requirements.

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4. Common Materials for Eccentric Flanges

Material selection depends on fluid type, 温度, そしてプレッシャー. 一般的な材料としては、:

• 炭素鋼 (A105, A350 LF2): Cost-effective for water, ガス, and non-corrosive liquids

• ステンレス鋼 (304, 316l): Excellent for corrosive environments and food-grade systems

• 合金鋼 (F11, F22): High strength and temperature resistance

• ニッケル合金 (モネル, インコネル, ハステロイ): For aggressive chemicals and seawater

• Duplex/Super Duplex Stainless Steel: High strength and chloride resistance for offshore applications

ササフランジ offers full documentation including EN 10204 3.1/3.2 certificates and NACE MR0175 compliance for oil & gas applications.

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5. Applications of Eccentric Flanges

Eccentric flanges are used in a wide range of industries where fluid flow, pressure maintenance, and system compatibility are critical. 代表的なアプリケーションには次のものがあります。:

ある) 油 & Gas Industry

• Pipeline connections with size transitions

• Crude oil and gas transportation lines

• Process plant pump inlets and outlets

b) 水処理施設

• Wastewater and stormwater pipelines

• Drainage systems requiring bottom-level flow

• Chemical dosing lines

c) 化学および石油化学

• Acidic and alkali pipelines with precise flow control

• Reactor outlet connections

• Slurry and solids-laden fluid systems

d) HVAC and Building Systems

• Chilled water or heating systems with varying pipe sizes

• Floor-level drainage where flat-bottom alignment is essential

e) Power Plants and Boilers

• Steam, 凝縮水, and feedwater systems

• Turbine and pump connections

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6. Advantages of Using Eccentric Flanges

ある) Smooth Flow Transition

By aligning the pipe bottoms (or tops), eccentric flanges eliminate turbulence, improving fluid efficiency and reducing wear.

b) Prevents Air Lock and Cavitation

In pump suction lines, eccentric flanges help avoid air pockets by keeping the liquid level consistent, preventing vibration and cavitation.

c) Facilitates Better Drainage

Eccentric flanges support complete draining of horizontal lines, especially useful in systems that need frequent cleaning or product changeover.

d) Reduced Sediment Build-up

In slurries and contaminated liquids, eccentric transitions avoid dead zones, reducing maintenance and pipe blockage risk.

e) Easy Installation with Custom Fit

ササフランジ manufactures eccentric flanges to match exact specifications, eliminating the need for excessive onsite adjustments.

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7. Design Considerations

When selecting eccentric flanges, エンジニアは考慮する必要があります:

• Nominal Pipe Sizes of both ends

• 顔のタイプ: 盛り上がった顔 (RF), 平面 (FF), or Ring-Type Joint (RTJ)

• 圧力定格: ANSIクラス 150, 300, 600, 等.

• Facing Alignment: Top-flat vs. bottom-flat based on flow direction

• 材質の適合性: Matching adjacent pipe and fluid characteristics

• Installation Position: Horizontal or vertical piping

Our engineering team at ササフランジ オファー custom flange design assistance to ensure flawless integration into your pipeline layout.

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8. 規格と認証

Eccentric flanges may not be as standardized as regular flanges, but they are often produced in accordance with:

• ASME B16.5 (for flanges and pressure ratings)

• ASME B16.47 (大径フランジ用)

• MSS SP-44

• NACE MR0175/ISO 15156 (for sour service)

• API 6A (for wellhead applications)

それぞれ ササフランジ product undergoes strict quality control, including dimensional inspection, PMIテスト, and hydrostatic testing where required.

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9. Customization Options

ササフランジ offers extensive customization services for eccentric flanges, 含む:

• Size transitions (例えば, 12″ × 8″, 10″ × 6″)

• Custom bore dimensions and tolerances

• Special coatings (FBE, PTFE, エポキシ, galvanization)

• ansi, DIN, JIS, and EN flange combinations

• CNC machining for tight dimensional control

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10. Summary Table: Eccentric vs. Concentric Connections