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 is a metal joint that expands/contracts
axially, allowing slight bending. Protective rods/rings and guide
supports prevent over-compensation. Angular and lateral joints
compensate for rotational/lateral deformations. Advantages:
space-saving, material-efficient, easy standardization, mass
production. Disadvantage: shorter lifespan. Commonly used in short,
low-temp, low-pressure pipes. With technological advancements, they
now handle up to 6.0 MPa in pipe systems. |
Slip-Type Expansion Joint | The slip-type expansion joint has inner and outer sleeves that can
move axially relative to each other. The gap is sealed with
stuffing box. Ensure pipes' ends move axially aligned. It comprises
sleeves, shells, sealing materials, etc. It compensates for axial
expansion and rotation of pipelines. Ideal for hot water, steam,
and grease. By sliding the inner sleeve, it adjusts for thermal
expansion. Connected to the pipeline, the inner sleeve freely
slides inside the shell. Uses a new synthetic seal between shell
and inner sleeve, resistant to heat, corrosion, and aging. Ensures
axial sliding while preventing media leakage. Temperature range:
-40 to 150°C, up to 350°C under special conditions. |
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 | Fabric expansion joints are made of fiber fabric, rubber, and other
heat-resistant materials. They compensate for fan and duct
vibration and deformation, addressing axial, lateral, and angular
issues. They offer simplified support design, corrosion resistance,
and noise and vibration reduction. Ideal for hot blast pipes and
power plant smoke and dust pipelines, they absorb sound and isolate
vibrations, reducing noise and vibration from boilers and fans.
They are simple, lightweight, and easy to maintain. |
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
- 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):
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, or fiber fabric compensators, possess several
key features:
- Compensation: They effectively compensate for axial and angular
displacement.
- Characteristics: These compensators offer no thrust, simplified
support design, corrosion resistance, high temperature resistance,
noise reduction, and vibration isolation.
- Ideal Application: Fabric compensators are particularly suitable
for use in 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 |
