Tube repair techniques used by CTI are based on offering cost-effective solutions for equipment life extension, beginning with a tube sleeve for heat exchanger repair.

Besides condensers, these patented tube repair techniques have successfully been applied to a wide variety of exchangers - fin-fan air coolers, process shell-and-tube exchangers, hydrogen coolers, HP feedwater heaters and many more.

The tube sleeve consists of two basic types:

For those units suffering from inlet-end erosion, Stress Corrosion Cracking, crevice corrosion or any problems related to the tube-ends, CTI offers its most cost-effective tube repair, the CTI Shield/Seal™, also known as a tube insert or ferrule. Although Shields are typically only 6" - 12" long, some applications have required Shield lengths up to 14 feet!

Some exchangers, however, suffer from full-length problems. In this case CTI Full Length Tube Liners™ can be an attractive alternative to that of a partial or full retube.

CTI has been of service to the electric utility, refinery, chemical, petro-chemical, commercial marine, U.S. Navy, paper mill, fertilizer, desal, and other industries, in over 35 countries worldwide.

In 1976, CTI developed a repair technique that today is recognized as the most widely used cost-effective system in the world. The CTI Shield/Seal™, is a thin-walled metallic tube insert made of highly durable alloys.

The Shield, also known as a ferrule, or tube ferrule, is expanded – either mechanically, hydraulically or a hybrid of the two – into existing tube ends, adding years of service to the equipment. Shields may be used for exchanger tubes suffering from:

• Tube end erosion/corrosion
• Stress Corrosion Cracking
• Crevice corrosion
• Localized pitting
• Ammonia grooving
• Improper tube expansion
• Weakened tube-to-tubesheet joints

Choosing the proper alloy of the Shield is critical. Selection is based on existing tube materials, the service of the HX, and the cause of the tube failures. Typically, the Shield alloy selected is superior, but galvanically compatible, to that of the existing tubes.

Materials available range from:

• Copper Alloys (Brass, 90/10, & 70/30 CuNi)
• Stainless Steel (austinetic, ferritic, duplex)
• Nickel based (C-276, Alloy 400 & 600, Ni 200, etc.)
• High Temperature (310S, 316H, etc.)
• Plus many more

An extensive inventory is maintained to accelerate response time for customer requirements.

The installation of Shields into new exchangers is becoming more and more popular. OEM's have called on CTI for Shields that will allow years of additional service life to the exchanger at a relatively low cost. Haldor Topsoe has recently included the use of CTI Shields into their design of new Waste Heat Boilers.

Since 1976, CTI has installed over 6 million Shields in over 35 countries for electric utilities, refineries, chemical plants, and commercial marine. The United States Navy has installed over a half million CTI Shields into condensers and heat exchangers spread across 60 ships.

Why replace the entire tube when only the first few inches need repair?

From steam condensers to HP Feedwater heaters, CTI has the answer that will SAVE YOU MONEY.

The patented CTI Full Length Tube Liner™ was developed for those units that suffer from full-length erosion/corrosion, pitting, general wall thinning and/or an overage of plugged tubes.

Tube I.D.'s are cleaned and the "Liners" (thin-walled tubes) installed. They are then hydraulically expanded their full length to intimate contact with the existing tubes. Finally, the Liners are cut, trimmed and roller expanded at the tubesheet areas, resulting in fully restored tubes.

Additional benefits include 1) the reduction of circulating water velocity by restoring plugged, leaking tubes to service and 2) the restoration of tube-end erosion/corrosion. Other benefits can include the installation without the removal of the waterbox or at low load.

Recently completed Liner installations include those for ExxonMobil, British Nuclear, Shell, Tonen and Trigen.

Next to steam condenser repair, the most common heat exchanger repaired by CTI is that for fin fan coolers. These are vital exchangers for oil refining plants.

One reason for CTI’s success with these units is their high retubing/replacement costs. This is due to 1) higher than normal tube costs, as they are finned tubes and 2) the location of the units, which are typically about 10-15 meters high.