CONDENSER & HEAT EXCHANGER REPAIR

 

CTI offers two basic types of sleeving for the repair of condensers and heat exchangers.  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.

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!

 

Unfortunately, some exchangers suffer from full-length problems. In this case, CTI Full Length Tube Liners™ can be a very attractive alternative to a partial or full retube.

 

CTI SHIELD/SEAL™ — U.S. PATENT #4,941,512

 

In 1976, CTI developed an advanced 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 Shields, also known as ferrules, are expanded – either mechanically, hydraulically or a hybrid of the two – into existing damaged 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.)
• And 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, for example, 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 alone has installed over a half-million CTI Shields into condensers and heat exchangers spread across 60 ships.

 This repair technique is not a "band-aid" repair but a true restoration that, in some instances, has extended the life of the exchanger by more than twenty years...

  

FULL LENGTH TUBE LINERS™ — U.S. PATENT

The patented CTI 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 Aramco, BP, Chevron, Exxon Mobil and Methanex.

FEEDWATER HEATERS

CTI's sleeving of high pressure feedwater heaters is performed via "Hybrid" expansion - hydraulic expansion for the full length of the Shields followed by mechanical  expansion at each end. 

This process will allow the feed water heater to operate efficiently for years. The Shields will not only protect damaged tubes from future failure, but will also recover plugged tubes to active circulation.

Company	Existing Tubes	CTI Shields
Plant	Problems	Quantity / Material
Date		Length
Colorado Springs	70/30 CuNi tubes suffering	464 Shields
*Martin Drake	SCC at inside face of 4½”	70/30 CuNi
Jul-97	Tubesheet	8” long
Florida Power & Light	Monel tubes suffering SCC at	2,566 Shields
*Port Everglades	inside face of 13” tubesheet	70/30 CuNi
Mar-98	SCC	18” long
Baltimore Gas & Electric	304ss tubes suffering SCC up to the	718 Shields
C.P. Crane	77” depth from the outlet tube ends	316Lss
Mar-98	SS304	87” long
Tampa Electric	Fretting of 304s tubes at baffles in the	238 Shields
*Big Bend	desuper heating zone due to vibration	316ss
Apr-98		43” / 74” lengths
Florida Power & Light	Monel tubes suffering SCC near	500 Shields
*Sanford	drains cooler end plate	70/30 CuNi
Nov-98		48” long
Pfizer, Inc	90/10 CuNi tubes damaged from	322 Shields
Groton, CT	vibration at 1st support sheet, 31” from	70/30 CuNi
Mar-99	tubesheet face	36” long
Tennessee Valley Authority	Monel tubes suffering SCC at	1,590 Shields
*Allen	inside face of 13” tubesheet	304ss
Sep-99		15” long
Southern Energy – California	304ss suffering failures in the	927 Shields
Contra Costa	desuperheating section, 96”	316Lss
Oct-99	from tubesheet face	110” long
Keyspan Corp.	Admiralty Brass tubes suffering	242 Shields
Northport	wall loss in sub-cooling zone,	70/30 CuNi
May-01	13½ Feet from tubesheet face	14 feet long
Electrabel (Belgium)	Carbon steel suffering pitting	3,944 Shields
Doel Nuclear	and corrosion up to 8” depth	316ss
Jun-01	from tubesheet face	12” long
*+South Texas Project Nuclear	304ss suffering intergranular	1,950 Shields
Wadsworth, TX	attack  and SCC up to 20”	316ss
Oct-01	depth from tubesheet face	22” /  13” lengths
Pacific Gas & Electric	Admiralty Brass tubes suffering from	72 Shields
Humboldt Bay	condensate corrosion	304ss
Apr-02		56” long
Reliant Energy	304ss suffering SCC up to	396 Shields
Portland	5 feet from tubesheet face	316ss
Apr-02		72” long
Enel (Italy)	Preventative maintenance.	370 Shields
Bastardo	To be installed in conjunction	316ss
Jul-02	with OEM in Milan, Italy	6” long
Pennsylvania P+L	304ss suffering SCC up to	1253 Shields
Martins Creek	5 feet from tubesheet face	316ss
Oct-02		56” / 60” lengths
Con Edison	Monel tubes suffering from SCC in	500 Shields
Waterside	tubesheet area	90/10 CuNi
Nov-02		9” long
Reliant Energy/Texas Genco	304ss suffering SCC at	1,333 Shields
Webster	Inside face of 11¾” tubesheet	AL-6XNss
Jan-03		16” long
Enel (Italy)	Preventative Maintenance	4,680 Shields
N/A	To be installed in conjunction with	321ss
Jul-03	OEM in Milan, Italy	6” long
Mirant	304ss suffering from	927 Shields
Contra Costa	Chloride-induced SCC	316ss
Dec-04	from tubesheet face	144” long
Eskom (So. Africa)	439ss suffering	1,088 Shields
Camden	from pitting corrosion	316ss
Sep-05		14” long
Mirant	304ss suffering from	700 Shields
Pittsburg	Chloride Pitting	316Lss
Dec-05		8 feet long
Detroit Edison	Cracking of 304 SS tubes	894 Shields
St. Clair	throughout the 12 ft.	Alloy 800
Sep-06	desuperheating zone (LP)	13 feet long
Xcel Energy	Two (2) units with	1595 Shields
*Black Dog	304SS tubes suffering from	317 SS
Mar-07	Stress Corrosion Cracking	67 inches long

A partial list of feedwater heater repairs to date:

(*) Denotes additional HP feedwater heaters were "Shielded” at a later date based on the success of the initial installation.

(+) Denotes portion of these Shields installed “downstream."

 FIN-FAN AIR COOLERS

Fin-fan air coolers have become an integral part of CTI’s restoration systems, enabling our customers to forestall costly retubings and/or bundle replacement. The sleeving of Carbon Steel finned tubes using stainless steel or Nickel alloys is now being implemented on new air coolers as well.

 

 

ADDITIONAL SERVICES

 

INSPECTIONS：

CTI technicians perform inspections on condensers and heat exchangers which include three-ball micrometer measurements, rigid borescope, and full length fiber-optic video probe inspection. Other services available upon request. 

 

The 3-ball micrometer inspection typically consists of tube I.D. readings taken at the various depths into the tubes. This will determine not only the extent and depth of erosion, but the necessary dimensions required for the CTI Shield. Extensions are also available.

 

CLEANING

CTI offers a wide variety of tube cleaning methods, from removing mud and obstructions (CTI Jet-brush) to light scale (rotary cutter/buffer or metal bladed cleaners) to heavy duty deposits (water tube drill).

 

ADDITIONAL PRODUCTS

 

TUBE CLEANERS      

      • CTI Nylon Jet-Brush

      • Wire Brush

      • Metal Bladed Cleaners

      • HP Water Drill

TUBE PLUGS 

      • Fiber   

      • Brass 

      • Rubber

      • Steel

      • High Pressure

 

TUBE CLEANING KITS

Kits include the following gear:

      • Air/Water Guns

      • Manifolds   

      • Hoses 

      • Fittings

      • Catch Nets

      • Talmac Rods

 

INSPECTION EQUIPMENT     

      • 3-Ball Micrometers

      • Rigid Video Boroscope

      • Fiberoptic Video Boroscope