Clam Shell Bellows Repair on Heat Exchanger

Saves the Cost of New Tubes for BASF

Many fixed tube heat exchangers have a bellows element in the shell to allow the tubes to expand at a different rate than the shell. A leak in this bellows cannot be tolerated and the repair is generally considered to be very expensive because it is believed that the tubes must be removed to replace the bellows. Senior Flexonics Pathway has developed a bellows replacement procedure called a clam shell technique that eliminates the need to retube the exchanger, thereby saving time and money. Following is an example of a typical clam shell repair that was done at Senior Flexonics Pathway’s shop. The same procedure can be done at a job site anywhere in the world by Senior Flexonics Pathway OnSite Services personnel. Total turnaround time can be a matter of days in an emergency.

Repair procedure for BASF:

• The heat exchanger was received at Senior Flexonics Pathwayand visually inspected.
• The existing bellows covers and shipping bars were removed.
• The failed bellows was removed by grinding and the attachment surface was inspected to check for any cracks in the base metal.
• The bellows attachment surface was measured to accurately determine the as-built diameter of the shell.
• A new bellows was built to ASME Section VI I I requirements and cut in half for installation by the clam shell technique.
• The new bellows was fit to the existing shell and tacked in place followed by fillet welding of the bellows to the shell and full penetration welding of the bellows longitudinal seam.
• All bellows welds were dye penetrant . examined and visually inspected.
• The shipping bars were reinstalled to protect the bellows in transit.
• New covers were installed.
• The completed assembly was prepared for shipment and returned.

With the new clam shell bellows installed, the heat exchanger is good for many years of additional service.

To find out more about expansion joints for ClamShell bellows repairs, contact Senior Flexonics Pathway.