Bellows Bellows type expansion joints manufactured by OSK shall be introduced in following pages


  • Bellows

    OSK manufactures metal formed bellows. The welding is also provided with a minimum of 1 to 2 longitudinal welding at the pipe, It consists of a pipe of waveforms with no seams in the circumferential direction and is perform to absorb axial movement, lateral deflection and angular rotation.

    Bellows Bellows
  • Multi-ply bellows

    It is a bellows formed by overlapping two or more ply of thin pipes. Compared to single-ply bellows of the same shape, the following features are mentioned.

    Multi-ply bellows>
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    Larger displacement absorbed
    By moving each layer independently, a larger displacement amount can be obtained compared to a single-ply bellows.
    Longer service life
    The life of the bellows is related to the expansion and contraction amount and fatigue limit, and it has a longer life than a single-layer bellows.
    More flexible
    Since the spring force of a multi-ply bellows is proportional to cube of each ply and number of ply, a multi-ply bellows operates with a smaller force than a single-layer bellows.
    Applicable in a high pressure condition
    bellows have design limitations due to pressure, but multi-ply bellows can be used for ultra-high pressure due to the increase or decrease in the number of ply.
  • Thick bellows

    As a bellows, it is very thick (3 to 22 mm) and does not have a circumferential welding at the top of the bellows, and it is possible to design suitable for heat exchangers even under high pressure. In addition, since it is hydraulic formed, it can be finished with good dimensional accuracy.

    Thick bellows Thick bellows
  • Toroidal bellows

    Since the cross section of the bellows is toroidal (Ω-shaped), stress concentration due to internal pressure does not occur, which makes it suitable for products for high pressure. In addition, each bottom part of bellows convolutions is equipped with a ring preciously machined.

    Toroidal bellows

Major bellows material

  • Austenitic Stainless Steel(General material for bellows with superior processing and welding performance)
    SUS304 SUS304L SUS310S SUS316 SUS316L SUS321
    A240 TP.304 A240 TP.304L A240 TP.310S A240 TP.316
    A240 TP.316L A240 TP.321 SA240 TP.304 SA240 TP.304L
    SA240 TP.310S SA240 TP.316 SA240 TP.316L SA240 TP.321
    SUS316LTP-S SUS321TP-S   
  • Austenitic – Ferrite duplex stainless steel (High sea water proof)
    SUS329J1 SUS329J3L SUS329J4L UNS S32506 DP-3 NAS64
  • Nickel alloys① (high resistance to heat, corrosion, oxidation and excellent high temperature characteristics such as creep )
    NCF600 NCF601 NCF625 B168 N06600 B168 N06601
    B443 N06625 B443 N06626 SB168 N06600
    SB168 N06601 SB443 N06625 SB443 N06626
  • Nickel alloys② (high resistance to acid, carburization and excellent high temperature characteristics)
    NCF800 NCF800H NCF825
    B409 N08800 B409 N08810 B409 N08811 B424 N08825
    SB409 N08800 SB409 N08810 SB409 N08811 SB424 N08825
  • Nickel alloys③ (Excellent resistance to corrosion and heat under oxidation circumstance)
    HW6022 HW0276 B575 N10276 B575 N06022 SB575 N10276
    SB575 N06022 HASTELLOY C-276 HASTELLOY C-22
  • Nickel-Copper alloys (Excellent resistance to sea water)
    NW4400 MONEL400 B127 N04400 SB127 N04400 ALLOY400
  • Titan (Especially excellent resistance to sea water)
    TP270 TP340 B265 Gr.1 B265 Gr.2 SB265 Gr.1
    SB265 Gr.2
  • Nickel (Excellent resistance to sea water, pure water, a water solution of neutral and alkaline salt)
    NW2200 NW2201 B162 N02200 B162 N02201 SB162 N02200
    SB162 N02201 Nickel200 Nickel201
  • Aluminum Alloy (Excellent resistance to corrosion, weldability and forming)
    A5052P B209 A95052
  • Carbon steel (Mainly used for heat exchangers)
    SM400B SPV235 SB410 SB450 SB480 SGV410 SGV450
    SGV480 SLA235A SLA235B STPG370-S STPT370-S
    A515 Gr.60 A515 Gr.65 A515 Gr.70 A516 Gr.60
    A516 Gr.65 A516 Gr.70 A662 Gr.A A53 Gr.A A106 Gr.A
    SA515 Gr.60 SA515 Gr.65 SA515 Gr.70 SA516 Gr.60
    SA516 Gr.65 SA516 Gr.70 SA662 Gr.A SA53 Gr.A SA106 Gr.A
  • Others
    Tantalum Cupper etc.

※Inconel/Incoloy/Monel products are under the trademark registered by Special Metals Corporation
※Hastelloy products are under the trademark registered by Haynes International, Inc.

The above mentioned materials are popular for forming bellows.
Other materials mentioned in the above can be applicable for bellows forming and please contact us, if nay.