Archive for July, 2013

  • Jul
  • 29
  • 2013

Leakage Rubber Bellow

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Leakage Rubber Bellow

Leakage Rubber Bellow

Leakage
It is most important to determine where the leak originated prior to implementing any corrective action. If leakage or weeping is occurring from any surface of the expansion joint, except where flanges meet, replace the joint immediately. If leakage occurs between the mating flange and the expansion joint flange, tighten all bolts. If this is not successful, turn off the system pressure, loosen all flange bolts and then re-tighten bolts in stages by alternating around the flange. Make sure there are washers under the bolt heads, particularly at the split in the retaining rings. There should be no gap at the retaining ring split. Remove the expansion joint and inspect both rubber flanges and pipe mating flanges for damage and surface condition. Repair or replace as required. Also, make sure the expansion joint is not over elongated as this can tend to pull the joint flange away from the mating flange resulting in leakage. If leakage persists, consult SilverFox
Root causes include: Under torqued bolts, irregular sealing surface (optimal mating surface is full face flat flanges); over extension and chemical attack by the media.
Corrective action; tighten the bolts to the manufacturers torque recommendations. Change to proper design and chemically compatible material. Measure the face to face dimension prior to replacement.

  • Jul
  • 11
  • 2013

Rubber Bellow Fatigue

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Blisters

Blisters

Blisters / Deformation / Ply Separation
Some blisters and deformation when on the external portions of an expansion joint may not adversely affect the performance of the expansion joint. These blisters or deformations are cosmetic in nature and do not require repair. If major blisters, deformations and/or ply separations or delaminations exist in the tube, the expansion joint should be replaced as soon as possible. The root cause of delamination is either over-torque bolts, chemical attack by the media, aged rubber or some other form of break in the inner tube layer. Corrective actions include replacing the aged rubber expansion joint and ensuring the correct material selection for the application.

  • Jul
  • 01
  • 2013

Rubber Bellow Fatigue

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troubleshootexpansionjointfailuesfigure1

Rubber Bellow Cracking

 

Familar Signs of Rubber Bellow Fatigue.
Cracking:
Exterior surface cracking is most commonly the result of aging and or elevated temperature. As rubber ages, it becomes hard and brittle and loses inherent flexibility & resilence. Cracking or crazing may not be serious if only the outer cover is involved & the fabric is not exposed. If necessary, repair onsite with rubber cement where cracks are minor. Carefully inspect cracks to determine if underlying fabric reinforcing plies are compromised. Cracking where the fabric is exposed & torn, indicates the expansion joint should be replaced. Such cracking is usually the result of excess extension, angular or lateral movements. Such cracking is identified by (1) a flattening of the arch, (2) cracks at the base of the arch &/or (3) cracks at the base of the flange. Cracking at the base of the flange/arch is more to do with movement & misalignment. Corrective action, measure the face to afce and lateral alignment prior to ordering a replacement and install control units to maintain acceptable movement limits of the expasnion joint during operation