Mechanical Repair

HYDRAULIC INSTALLATION OF FULL LENGTH LINERS AND SLEEVES

Hydraulic expansion is performed by introducing water at a high internal pressure within a sleeve, between 2 seals, to expand the sleeve to a point of contact between the sleeve and the parent tube.

FULL LENGTH LINERS:  Full length liners are installed as an alternative to full re-tubes of straight tube heat exchangers.  The liners are installed into leaking tubes to recover them and bring the unit back close to original design parameters.  They are also installed into tubes that have been found by NDE to be close to failure, hence, eliminating the need for an emergency shutdown required to plug the tubes.  The liners are hydraulically expanded the full length of the tube to make contact with the tube and adding wall thickness.

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BENEFITS OF FULL LENGTH LINERS VS RE-TUBE:

TIME.  For a full re-tube, the time required to perform the work includes time for removing the existing tubes.  The removal and cleaning of the support plates for tube installation accounts for up to 75% of the time required for a re-tube.  Full length liners are installed without removing the existing (parent) tubes.  Instead of 4 to 6 weeks required for a re-tube, full length liners can be installed within 1 to 2 weeks making the unit available for service quicker.

COST.  A full re-tube requires the purchase of replacement tubes for the whole unit.  The installation of full length liners only requires the purchase of material that is needed to repair the leaking and damaged tubes.  This is a considerable difference.

RELIABILITY.  Full length liners are every bit as reliable as a new tube.

SLEEVES:  Sleeves are short (6” to 18” long) tubes hydraulically installed on the inlet end of parent tubes.  They are installed to act like a wear plate to decrease the damage done to the parent tube due to inlet erosion.  The sleeves can be replaced after they have outlived their usefulness.  Sleeves can also be used to make repairs to tubes where the defect is directly behind the tubesheet.  This can keep tubes that normally would have to be plugged, open and performing as intended.

BENEFITS:

Increase the life expectancy of tubes

Can be used in straight and U-tubes

return old, defective or plugged tubes back into service

Why use hydraulic expansion over mechanical expansion?

  • No step-expanding.  Any length can be done in one quick operation
  • Minimal work hardening of the tube material during expansion means that even difficult tube materials such as titanium or superduplex stainless can be expanded successfully.
  • Less wall reduction and less stress concentration from the expanded to the unexpanded portion of the tube results in longer tube life.
  • Improved quality – each tube expansion is controlled by the system parameters and not influenced by the operator.

If either of these options may help you with your exchanger, please request a quote.  We will be happy to help you with anything we can.