ENHANCED TUBES

"Enhanced Tubes" are the replacement for the old standard "Smooth Bore Tubes" used on the Condenser and Evaporator bundles of Chillers. The enhancements vary from mild to radical but all of them alter the flow characteristics of the water as it flows through the tube.

As energy becomes a more important area of concentration, Chiller manufacturers have opted to use more energy efficient Condenser Tubes. These tubes alter the flow of water as it moves through the Condenser bundle, have increased surface area, and appear to be thinner at the weakest point on the tube.

The Water Treatment Industry has failed to be proactive in its response to the new Enhanced Tubes.

Enhanced Tubes, under certain conditions, have a much higher potential for deposition than Smooth Bore Tubes. If deposited, the Enhanced Tubes will have dramatic useful life reductions.

We have any number of cases in house where Enhanced Tubes have pitted inside of the first year of operation or where they have prematurely failed.

· Flow seems to be a major contributor to the deposition in Enhanced tubes.

Many customers periodically lay-up Condensers with high solids Tower Water. This may be due to reduced capacity needs; Plate/Plate Free Cooling availability; or Seasonal Lay-up. Lack of flow increases the deposition potential.

· Once deposited, the Enhanced Tubes may become subjected to Biologically Induced Under-deposit Corrosion conditions.

Most customers punch the Condenser Tubes on an annual basis. They may or may not use the correct brushes to be effective in cleaning of the Enhanced Tubes. They generally "clean blind" and have no way of determining the effectiveness of the cleaning.

· The Water Treatment Industry has, in general, made no allowances for the deposition potential of the Enhanced Tubes.

The Industry uses precipitation, in various forms, as a corrosion inhibitor for mild steel. One of the more common treatments involves Ortho Phosphate, or products, which revert to Ortho Phosphate, as the mild steel corrosion inhibitor. With Enhanced Tube Condensers, this may be the formula for disaster.

· No allowances are being made to insure a good corrosion barrier exists on the Enhanced Tubes.

The only product used to protect copper in a system is the azole usually in the form of Tolytriazole. The Treatment Suppliers are depending on stoichiometric balancing of the treatment program where the mild steel corrosion inhibitor, or tracer, is balanced against the Tolytriazole component of the Chemical Drum. Invariably, this does not work as the Tolytriazole is decomposed or consumed at higher rates often times leaving the system unprotected from copper corrosion.

As a check, the Treatment Supplier may utilize Copper Corrosion Coupons but these are "after the fact" and do not account for the heat load of the Condenser Tube. Chemical reactions generally occur faster as heat is added and the Condenser Tube may be as much as 50 Degrees F higher temperature than the Corrosion Coupon.

1. The customer should utilize independent analysis of the Treatment Program to investigate problem areas, which may damage equipment. Remember, the Water Treatment Rep. works for the Drum and the customer generally does not have a clue as to what is happening chemically in any system, and as a result, has no one representing their interests.

2. Enhanced Tube Condensers must be cleaned properly using the correct brushes.

3. Enhanced Tube Condensers must be borescoped before and after each cleaning to insure removal of all deposits.

4. Enhanced Tube Condensers must have sufficient flow, to reduce deposition potential; allow for reformation of the corrosion barrier film; and to allow for bacterial control.

5. Enhanced Tube Condensers must have sufficient Copper Corrosion Inhibitor (Tolytriazole) present at all times to reduce the chances of pitting.

6. Enhanced Tube Condensers must use Water Treatment Technology, which reduces the chances of deposition based on Raw water characteristics and system conditions.

7. Enhanced Tube Condensers must have a very good alternating biocide program designed for both bulk water sterilization and penetration without increasing copper corrosion potential.

8. Enhanced Tube Condensers must be laid-up properly.