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How To Inspect a Rubber Expansion Joint in Service?

2016/12/23 9:29:26      Clickú║

If an expansion joint is in a critical service condition and is 5 or more years old, consideration should be given to maintaining a spare or replacing the unit at a scheduled outage. If the service is not of a critical nature, observe the expansion joint on a regular basis and plan to replace after 10 years service. Applications vary and life can be as long as 30 years in some cases. Following is the procedures to inspect a rubber expansion joint in service:

a. Cracking. (Sun Checking) Cracking may not be serious if only the outer cover is involved and the fabric is not exposed. If necessary, repair on site with rubber cement where cracks are minor. Cracking where the fabric is exposed and torn, indicates the expansion joint should be replaced. Such cracking is usually the result of excess extension, angular or lateral movements.

b. Blisters-Deformation-Ply Separation. Some blisters or deformations, when on the external portions of an expansion joint, may not affect the proper performance of the expansion joint. These blisters or deformations are cosmetic in nature and do not require repair. If major blisters, deformations or ply separations exist in the tube, the expansion joint should be replaced as soon as possible.

c. Metal Reinforcement. If the metal reinforcement of an expansion joint is visible through the cover, the expansion joint should be replaced as soon as possible.

d. Dimensions. Any inspections should verify that the installation is correct; that there is no excessive misalignment between the flanges; and that the installed face-to-face dimension is correct. Check for over-elongation, over-compression, lateral or angular misalignment. If incorrect installation has caused the expansion joint to fall, adjust the piping and order a new expansion joint to fit the existing installation.

e. Rubber Deterioration. If the joint feels soft or gummy, plan to replace the expansion joint as soon as possible.

f. Leakage. If leaking 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 expansion joint, tighten all bolts. If this is not successful, turn off the system pressure, loosen all flange bolts and then retighten bolts in stages by alternating around the flange.