1. Expansion joints(compensators)

• Introduction

Expansion joints are commonly referred to as compensators. They consist of one or more bellows (an elastic component) as the main working body, as well as connectors at both ends, supports, flanges, conduits, and other accessories. Expansion joints are a flexible structures installed on vessel shells or pipelines to compensate for additional stresses caused by temperature differences and mechanical vibrations. By utilizing the effective expansion and contraction of the bellows, they compensate dimensional changes in pipelines, conduits, vessels and so on, which are caused by thermal expansion and contraction, or compensate for axial, lateral, and angular displacements of pipelines, conduits, vessels, etc. They can also be used for noise and vibration reduction and heating supply systems. In order to prevent deformation or damage to heating pipelines caused by thermal expansion or temperature stress when the heating pipelines are heated, compensators need to be installed on the pipelines to compensate for thermal expansion of the pipelines, thereby reducing the stress on the pipeline walls and the forces exerting on valves or support structures.

As expansion joints are elastic compensating components capable of free expansion and contraction, they have the advantages of reliable operation, good performance, and compact structure,and others.Hence they are widely used in departments such as chemical engineering, metallurgy,nuclear energy,and the like. There are various forms of expansion joints used on vessels, with the U-shaped expansion joint being the most widely used in terms of the shape of bellows, followed by Ω-shaped and C-shaped joints. As for expansion joints used on pipelines, they are classified according to structural compensation into universal expansion joint, pressure balanced expansion joint, hinged expansion joint, and gimbal expansion joint.

• Classification

• Special materials

Super Austenitic Stainless Steel: 254SMO, 904L, AL6XN
- These alloys exhibit high resistance to corrosion, particularly in harsh environments containing chloride ions. They are often used in applications requiring excellent corrosion resistance and high strength.

Duplex Stainless Steel: 2205 Dual Phase Steel (S31803)
- Duplex stainless steels offer a combination of high strength and excellent corrosion resistance. They are commonly used in applications requiring resistance to stress corrosion cracking and pitting corrosion.

Nickel-Based Alloy Steel: INCOLOY800/800H/800HT/840/825, INCONEL600/601/690/625/X-750
- Nickel-based alloy steels offer exceptional high-temperature strength and corrosion resistance. They are commonly used in applications such as heat exchangers, chemical processing equipment, and gas turbines.

Hastelloy Alloy: C-276/C-22/X, MONEL400/K500
- Hastelloy alloys exhibit outstanding resistance to a wide range of corrosive environments, including oxidizing and reducing acids, and high-temperature gaseous environments. MONEL alloys offer excellent resistance to corrosion and erosion in marine and chemical environments.

Pure Nickel: N4, N6 (Ni200, Ni201)
- Pure nickel exhibits high resistance to corrosion and oxidation at elevated temperatures. It is commonly used in chemical processing, electronics, and aerospace industries.

Titanium Plate for Stamping: GR1, GR2, TA1, TA2
- Titanium plates are known for their high strength-to-weight ratio, excellent corrosion resistance, and biocompatibility. They are widely used in aerospace, marine, chemical processing, and medical applications.

Austenitic Stainless Steel: SUS304, SUS304L, SUS316, SUS316L, SUS310S, SUS321, SUS316Ti
- Austenitic stainless steels are non-magnetic and offer excellent corrosion resistance, good formability, and weldability. They are commonly used in various industries, including food processing, chemical processing, and medical devices.

2. Non-metallic Expansion joints

• Non-metallic compensators/expansion joint types

Non-metallic compensators can be divided into the following types: straight cylindrical non-metallic expansion joints, compound non-metallic expansion joints, angular non-metallic expansion joints, and square non-metallic expansion joints.

Rectangular non-metallic compensators are mainly used in flue ducts of power plants to absorb thermal displacement and/or shock absorption. The connection types for rectangular non-metallic compensators include flange connection and nozzle connection.

• Common structural types of non-metallic compensators (non-metallic expansion joints) include the following six:

• Technical parameters of non-metallic compensators (non-metallic expansion joints):

• Applied range of non-metallic compensators (non-metallic expansion joints):

Gas turbine exhaust duct

Desulfurization system

Flue ducts and exhaust systems of various industries

Coal-fired boilers, circulating sulfurized bed boilers

Flue ducts of waste heat boilers

3. Round Non-metallic Compensator/Expansion Joint

Circular Non-metallic Compensators/Expansion Joints offer several key advantages:

1. Thermal Expansion Compensation: They can compensate in multiple directions, providing superior flexibility compared to metal compensators, which typically offer single-axis compensation.

2. Alignment Error Compensation: Fiber compensators effectively eliminate misalignment issues resulting from system errors during pipeline connections.

3. Noise Reduction and Vibration Isolation: Inherent sound absorption and vibration isolation properties of fiber fabric and insulation cotton reduce noise and vibration in systems such as boilers and fans.

4. No Reverse Thrust: With fiber fabric as the main material, there is no transmission of force, simplifying design and avoiding the need for large supports, saving on materials and labor.

5. High-Temperature and Corrosion Resistance: Selected fluoroplastics and silicone materials offer excellent resistance to high temperatures and corrosion.

6. Reliable Sealing Performance: Fiber compensators ensure leak-free operation with a complete production and assembly system.

7. Lightweight, Simple Structure, Easy Installation and Maintenance: Their lightweight and simple structure make them convenient to install and maintain.

8. Cost-Effectiveness: They are priced at 1/2 to 1/5 of imported metal compensators, offering good damping effects and long service life. Large flanges without gaskets reduce costs and allow for direct installation.