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Re-tube Existing Chiller Due to the massive size of the chiller unit and the access constraints the most cost effective solution to repair the refrigeration system is to re-tube the existing chiller vessel. Access for the re-tubing process is provided through an existing window on the south wall of the mechanical room. No major building modifications should be necessary to complete fl�is process except for possibly removing the window frame to provide additional clearance to remove and reinstall tl�e tubes. The re-tubing process will include: • Cut openings in the shell to assist in installing the tubes; * Cut out old tubes • Pull tube stubs from each head • Prep tube holes and inspect baffles or tube siippo�•ts • Check gaskets between pass section of chiller, replace if necessary • Clean chiller ai�d prepare shell access openings. This includes cleaning inside of belt ends and tube sheets to "like n��' condition". Once cleaned, a protective coating will be placed over t��e metal per the manufacturer's recommendation. • Install new tubes • Roll new tubes in each head • Re-weld access openings • Spot X-ray of welds on access openings • Pressure test • Reinstall window (if required) • Reinstall foam insulation in repair area. Evaluate a less permanent insulation covering for the bell ends during design for easier access. • Charge system with brine and ammonia • Recertify the vessel (R-stamp) — the existing vessel can be re-tubed with the same tube material and not require recertification. ��owe�ver, one contractor stated that they would need to cut into the vessel to aid in the installation of the tubes and therefore recertification is required. Other related improvements that would be included in the re-tubing project include the following. These items can be bid as alternate bids if desired. • Installing a perma��ent support systetr� on each end of the chiller to assist in removing the end be3fs when maintenance or inspection is required. • Painting the high pressure receiver. • Installing site glasses on the chiller vessel. Replace the Existing Chiller A second option is to replace tlie ecisting shell and tube chiller and surge drun� with a new chiller and surge drum. This option was included for comparison purposes and in case the shell of the existing elaiiler vessel was found to be in poor shape which is not the case. Replacing the existing chiller vessel is expensive mainly due to the limited access to the n2�chanical room for this large vesseL The most feasible way of installing a new shell and tube type chiller is to remove and replace sections of the existing roof which increases the cost of this option substantially. The cost estimate for r�,�� option is included in the table below and includes the same related improvements as discussed in the previous section.