1. Expansion joints(compensators)
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.
| Main Item | Classification | Description |
Metal Expansion Joint | Elbow Expansion Joint | Bend the pipe into a U-shaped or other shape, also known as tension
bends,are a type of expansion joint that utilizes the elastic
deformation ability of the form to compensate. Its advantages are
good strength, long service life, and on-site production.The
disadvantages are space-consuming, high steel consumption, and high
friction resistance. This type of expansion joint is widely used in
various steam piping and long pipes. |
Bellows Expansion Joint
| A bellows expansion joint, crafted from metal bellows, enables
axial expansion and contraction along the pipeline and permits
slight bending. To prevent overextension, protective rods or rings
are installed at each end, with guide supports on connected
pipelines. Angular and lateral joints address rotational and
lateral pipeline deformations. While offering space and material
savings, standardization, and mass production benefits, they have a
shorter lifespan. Primarily used in short, low-temperature, and
pressure pipelines, advancements in production technology are
broadening their applications, now supporting pressures up to 6.0
MPa. |
Slip-Type Expansion Joint | The slip-type expansion joint features inner and outer sleeves that
move axially. Sealed with a stuffing box, it maintains pipe
alignment while compensating for axial expansion and rotation. With
small dimensions and high compensation capacity, it suits hot
water, steam, and grease applications. Thermal expansion is
addressed by sliding the inner sleeve against the outer one.
Equipped with a high-performance self-sealing dynamic seal, it
accommodates pipeline movement while meeting sealing requirements.
A specialized synthetic seal withstands high temperatures,
corrosion, and aging, functioning in temperatures from -40 to 150
degrees Celsius, and up to 350 degrees Celsius in special cases.
This design ensures axial movement while preventing medium leakage. |
Non-metallic Expansion Joint | Rubber Expansion Joint | Composed of rubber and rubber-fiber composite materials, steel
flanges, sleeves, and insulation materials, it is mainly used for
flexible connections between various fans and ducts. Its functions
include shock absorption, noise reduction, sealing, medium
resistance, easy displacement and installation. It is an ideal
accessory for shock absorption, noise reduction, smoke and dust
removal in the field of environmental protection. |
Fabric Expansion Joint | The fabric expansion joint is mainly made of fiber fabric, rubber,
and other high temperature resistant materials. It can compensate
for the vibration and deformation of fans and ducts.Fabric
expansion joints can compensate for axial, lateral, and angular
products, with features such as no thrust, simplified support
design, corrosion resistance, high temperature resistance, noise
reduction, vibration reduction,and others.It is particularly
suitable for hot blast pipes and smoke and dust pipeline of power
plant.The non-metallic compensator's fiber fabric and insulation
cotton itself have the functions of sound absorption and vibration
isolation, therefore they can effectively reducing the noise and
vibration of boiler, fan, and other systems. Simple structure,
light weight, and easy maintenance. |
Super Austenitic Stainless Steel:254SMO,904L,AL6XN
Duplex Stainless Steel :2205
Dual phase steel (S31803)
Nickel Based Alloy
Steel:INCOLOY800/800H/800HT/840/825,INCONEL600/601/690/625/X-750
Hastelloy Alloy C-276/C-22/X,MONEL400/K500
Pure Nickel:N4,N6(Ni200,Ni201)
Titanium Plate For Stamping:GR1,GR2,TA1,TA2
Austenitic Stainless
Steel:SUS304,SUS304L,SUS316,SUS316L,SUS310S,SUS321,SUS316Ti
2. Non-metallic Expansion joints
Types and Applications of Non-Metallic Compensators:
Non-metallic compensators, crucial components in various industrial
settings, can be broadly categorized into four types: straight
cylindrical, compound, angular, and square non-metallic expansion
joints.
Straight Cylindrical Non-Metallic Expansion Joints offer a simple
yet effective solution for absorbing thermal displacement and
reducing stress in piping systems.
Compound Non-Metallic Expansion Joints are designed to handle more
complex displacement patterns, often found in curved or irregularly
shaped pipelines.
Angular Non-Metallic Expansion Joints are specifically engineered
to accommodate angular movements, making them ideal for
applications where piping systems experience changes in direction.
Square Non-Metallic Expansion Joints are suitable for square-shaped
ducts and piping, providing efficient thermal displacement
compensation.
Among these types, Rectangular Non-Metallic Compensators play a
vital role in power plant flue ducts. Their primary function is to
absorb thermal displacement and/or shock absorption, ensuring
smooth and efficient operation of the flue system. Rectangular
compensators come in various connection types, including flange
connections and nozzle connections, allowing for flexibility in
installation and integration into existing systems.
- 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):
Compensating segment length(h/m)
| 100 | 200 | 250 | 300 | 350 | 400 | 450 | 500 | 550 | 600 | 650 | 700 | 800 | 900 |
Compensation volume(nm)
| Axial displacement (x/m) | -30 | -50 | -75 | -85 | -105 | -125 | -130 | -140 | -165 | -175 | -195 | -205 | -225 | -240 |
| +15 | +20 | +30 | +36 | +45 | +45 | +50 | +55 | +58 | +62 | +66 | +70 | +74 | +80 |
Lateral displacement (y/m) | ±10 | ±15 | ±25 | ±30 | ±45 | ±50 | ±60 | ±68 | ±7o | ±73 | ±75 | ±80 | ±85 | ±90 |
Working Temperature (t°C) | a=100-200,b=200-300,c=300-450,d=450-500,e=500-600,f=600-700,g=700-1000 |
Working pressure P(Kpa) | ±10~±300,if the user requires, the pressure beyond the range, can
be designed separately. |
Flow rate | a——b | v=8——15 |
| c——d | v=8——20 |
- 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. Fiber fabric compensators / expansion joints
Fabric compensators (fiber fabric compensators)/expansion joints
have the following features:
Purpose: They can compensate for axial and angular displacement,
with characteristics such as no thrust, simplified support design,
corrosion resistance, high temperature resistance, noise reduction,
and vibration isolation, making them particularly suitable for hot
air ducts and flue ducts.
Parameters table for circular non-metallic compensators/expansion
joints:
Circular product specifications | Dw | D1 | D2 | D3 | b | d | Number of bolt holes(n) |
mm |
| Φ108 | 108 | 200 | 164 | 110 | 10 | 14 | 4 |
| Φ159 | 159 | 251 | 215 | 161 | 8 |
| Φ219 | 219 | 311 | 275 | 221 |
| Φ273 | 273 | 365 | 330 | 275 | 12 |
| Φ325 | 325 | 427 | 385 | 327 |
| Φ377 | 377 | 479 | 435 | 379 |
| Φ426 | 426 | 528 | 490 | 428 |
| Φ480 | 480 | 595 | 540 | 483 | 12 | 18 |
| Φ530 | 530 | 645 | 600 | 533 |
| Φ630 | 630 | 745 | 700 | 633 |
| Φ720 | 720 | 843 | 800 | 723 | 16 |
| Φ820 | 820 | 943 | 900 | 823 | 20 |
| Φ920 | 920 | 1043 | 1000 | 923 |
| Φ1020 | 1020 | 1153 | 1100 | 1023 | 14 | 22 |
| Φ1120 | 1120 | 1253 | 1200 | t123 |
| Φ1220 | 1220 | 1353 | 1300 | 1223 |
| Φ1320 | 1320 | 1453 | 1400 | 1323 | 24 |
| Φ1420 | 1420 | 1553 | 1500 | 1423 | 16 | 28 |
| Φ1820 | 1820 | 1963 | 1910 | 1823 | 26 |
| Φ2020 | 2020 | 2163 | 2110 | 2023 | 32 |
| Φ2220 | 2220 | 2363 | 2310 | 2223 | 18 | 36 |
| Φ2420 | 2420 | 2563 | 2510 | 2423 | 40 |
| Φ2820 | 2820 | 2983 | 2915 | 2823 | 20 | 32 | 44 |
| Φ3220 | 3220 | 3383 | 3315 | 3223 | 22 | 52 |
| Φ3620 | 3620 | 3783 | 3715 | 3623 | 56 |
