Every fixed equipment, mechanical and/or reliability engineer, corrosion specialist, inspector, etc. at refinery, chemical and petrochemical plants is aware of the extreme financial penalties and, more importantly, the potential dangers associated with heat exchanger tube failures.
These failures and related emergency shutdowns presently cost the industry millions of dollars per day and billions of dollars per year on a worldwide basis.
In 1985, CTI Industries in Orange, Conn., developed a technology that extends the service life of new or eroded/corroded heat exchanger tubes — the Full Length Tube Liner™.
CTI Full Length Tube Liners are thin-walled tubes that are hydraulically expanded into the existing heat exchanger tubes. They are constructed from a number of different erosion/corrosion resistant alloys. This allows the metallurgist to select a material that will resolve the specific problem of the exchanger tubes in question.
The installation process begins by installing liners into the parent tubes with their ends protruding from the header box. An expansion chuck — which is connected to CTI’s custom air powered hydraulic liner pump — is attached at one end, while a bleed chuck is affixed to the opposite end. The liner is filled with water and the air is released. The pump pressurizes the water until the liner is expanded full length to a contact fit with the tube IDs. When the expansion process is completed, liner ends are cut and trimmed flush to the tube ends, then roller expanded at each tubesheet.
Although this technology is more commonly applied to existing, damaged tubes, in 2006 the BP Carson Refinery was the first plant in the United States to install CTI Full Length Tube Liners into new carbon steel tubes in-situ into two bundles.
The major factors that prompted BP’s metallurgist and team of reliability engineers to utilize this technology were the historical problems experienced with these units in previous years, including the following:
• Excessive corrosion rate of the parent tubes in a very short time period.
• In-service tube failures leading to unscheduled shutdowns.
• Undersized water wash and unequal water wash distribution.
• Non-desaltable (phantom) chlorides.
• Chemical inhibition program could not manage the corrosion issues.
Rather than wait for these failures and related production losses to occur, the decision was made by BP to contract CTI Industries to install 389 liners, manufactured from Hastelloy C276 material, into each of the two bundles.
The installation was achieved through existing header box plug holes and the CTI field crew completed the project ahead of schedule, enabling the refinery to return the coolers to service one day ahead of schedule.
Since that time, oil companies such as ExxonMobil, ConocoPhillips/Phillips 66, Shell, SK Energy and Total, to name a few, have utilized this technology at numerous refineries across the United States, Canada, Europe and Asia.
CTI has worked closely with several plants located along the Gulf Coast to keep its heat exchangers operating without any unexpected tube issues or failures. Working in tandem with the design engineering and inspection groups can result in a proactive preventative maintenance program. It starts by closely monitoring the tubes during scheduled turnarounds on a regular basis, measuring and documenting the condition of tube IDs and may include temporary preventive tube plugging.
Depending on the type of exchanger and the application, customers can select alloys such as 316 Stainless Steel, Alloy 825, C-276 and others.
Since 2000, CTI has installed thousands of Full Length Tube Liners at locations from Pascagoula, Miss., to Corpus Christi, Texas, and restored heat exchangers with operating pressures ranging from 35 pounds per square inch (psig) to more than 1,000 psig. In each case, CTI has returned damaged units back to full operation and extended the service life of the exchangers.
For more information, visit www.cti-ind.com or call (800) 446-0060.