CB Clamshell
metal expansion joints

CB Clamshell
metal expansion joints

CB Clamshell<br/>
metal expansion joints
Typical CB clamshell expansion joint

Item Description
1 Clamshell bellows 1-ply
2 Weld end

CB Clamshell
metal expansion joints


  • Bellows or expansion joints split into longitudinal segments for installation without opening pipework.
  • Temporary repair solution for damaged expansion joints.
  • Can handle axial, lateral and angular movements.
  • The permissible combination and magnitude of movements depends on the application and the existing expansion joint that is to be repaired.


  • In non-critical failures, permits repairs to expansion joints without shutting the plant down.
  • Provides temporary expansion joint repair until a scheduled outage.
  • In critical failures, enables rapid restart after an emergency shutdown.
  • Can facilitate repair when access to the expansion joint is via confined spaces.

Operating range

Diameter: Up to 4,250 mm (170”)
Process temperature: Up to 900 °C (1,650 °F)
Pressure: Up to 80 bar (1,200 PSI)


  • Bellows material: SA240-304, SA240-304L, SA240-316, SA240-316L, SA240-321, Inconel® 625 LCF (low cycle fatigue) nickel alloy, Inconel® 800H, other materials on request.
  • Bellows basics: single ply, formed by punch mandrel, thin-wall. Cut into longitudinal segments once manufacture is complete. Ply thickness 0.7 mm (0.03”) ... 3.0 mm (0.12”).
  • Weld ends and/or rings: material selected to suit the application

Standards and approvals

  • B31.3 process piping
  • ASME Section VIII, Division 1, R (repair, unfired) pressure vessel certificate.
  • European Pressure Equipment Directive (PED) 97/23/CE
  • Expansion Joint Manufacturers Association (EJMA)
  • ISO 9001:2008

Functional description

CB Clamshell expansion joints are cut into (most commonly two) longitudinal segments once their manufacture is complete. Because they have been cut, they can be installed around existing pipe with no need for the pipe itself to be cut or opened. Once the pieces are in place, they are welded together by expert welders, to create the whole expansion joint.


Quality control and testing options:
  • Full x-ray of bellows longitudinal seam weld before formation of convolutions.
  • Full dye penetrant test of bellows longitudinal seam weld inside and outside before and after forming of convolutions.
  • 100 % dye penetrant test of bellows attachment welds (if applicable). This would be done prior to the expansion joint being split into segments.
  • Impact testing of weld ends
  • Hardness test
  • Positive Material Identification

  • Expert clamshell bellows welders available to perform these highly-specialized welds.
  • All field welds can be 100 % dye penetrant tested.
  • Welding teams able to work at height and in confined spaces, provided safety requirements are met.
  • Experienced supervision by our field service personnel available for overall expansion joint repair guidance.

Similar products

AN Type expansion joints

  • Tied custom metal expansion joints for general pressure applications.
  • Designed for, and cover the mid temperature and pressure range for general process equipment.
  • Mainly for angular movements.
  • Tied metal expansion joints retain pressure thrust developed by internal pressure, through the use of hardware.

AX Type expansion joints

  • Untied custom metal expansion joints for general pressure applications.
  • Designed to cover the mid temperature and pressure range for general process equipment.
  • Mainly intended for axial movements.
  • Multiply bellows with low spring rate and high cycle life.

DH1S Danmuff metal expansion joints

  • Untied metal expansion joints mainly for district heating applications.
  • External shroud with torsion protection, for district heating.
  • Can be installed in series.
  • Designed for large axial movements.

Inquire about individual solutions

We develop and produce customer-specific special and individual solutions for every application.

Inquire now Discover reference projects
Back to the overview