Single axial expansion joint

Product Introduction

I. Structural composition

The single axial expansion joint is mainly composed of the following components:

1. Bellows: Core component, absorbs pipeline displacement through flexible deformation, the material is mostly austenitic stainless steel (such as 0Cr18Ni9, 0Cr17Ni12Mo2) or corrosion-resistant alloy, adapted to the temperature range-200~550℃.

2. End tube/flange: Connect pipes or equipment, the material is usually consistent with the material of the pipe, supporting welding or flanged connections.

3. Guide tube (liner tube): Installed inside the bellows to reduce the scouring of the bellows by the medium and guide the fluid to flow smoothly.

4. Limit rod/pull rod: Fixed bellows length during transportation, some models are equipped with anti-instability guide limit rod (used in multi-node design).

2. Working principle

Through the axial compression or tensile deformation of the bellows, it absorbs the temperature change and mechanical vibration caused by the pipeAxial displacementWhile a small amount of lateral or angular displacement can be compensated. Its external pressure design (the bellows is externally pressurized and the interior is ventilated with atmosphere) can prevent impurity accumulation and condensate freezing problems.

III. Main Features

1. Outstanding axial compensation capability: Specially designed for straight pipe sections, the compensation amount can reach tens to hundreds of millimeters, and the compensation amount is greater when multiple nodes are connected in series.

2. Anti-instability optimization: The external pressure structure avoids columnar instability, and some models add external bending sleeves to enhance bending ability.

3. Economy and Lightweight: Simple structure, low manufacturing cost, suitable for small and medium diameter pipeline.

4. Easy maintenance: The condensed water can be removed by the drain valve when it is out of operation to avoid corrosion.

Applicable scenarios

1. Thermal pipeline: Such as cement plant waste heat power generation, power plant steam pipeline, compensate for thermal expansion caused by temperature.

2. Chemical Engineering and Metallurgy: To handle corrosive media or high-pressure gas, it should be used in combination with the guide tube.

3. Equipment connectionSuch as motor shaft elongation compensation and connection of tertiary air duct with calciner to prevent structural stress damage.

V. Precautions for selection and installation

1. Parameter Provision: It is necessary to specify the medium pressure, temperature, compensation amount and pipe diameter to the manufacturer, and professional design will guarantee the life.

2. Fixed bracket: The main fixing bracket must be set to bear the pressure thrust (formula: Fp =100× P × A) to avoid overload of the bellows.

3. Pre-deformation treatment: Adjust the length by adjusting the pull rod before installation to adapt to the difference between cold state and working state.

4. Transportation protection: After installation, remove the transport limit lever to ensure that the compensation function is activated normally.

VI. DERIVATION TYPE

• bending type: Add external bending sleeve to improve lateral stability.

• External pressure type: The bellows is subjected to external pressure, which is suitable for large compensation scene.

• Fully buried: Suitable for underground pipeline, optimized anti-corrosion performance.

        Reference standard: GB/T 12777 (General technical specifications for expansion joints of metal bellows). In practical application, materials and structures should be selected according to working conditions, and the wear of the guide tube and the fatigue of the bellows should be checked regularly.