Hot Shell FCC Expansion Joint for Conoco

Includes the Latest Senior Flexonics Pathway Design Features

Reactor standpipe expansion joints are critical FCC components. When the Conoco South Humberside Refi nery ordered a new reactor standpipe expansion joint, they incorporated the latest design features to insure maximum reliability and safety. Many of these features were developed by Senior Flexonics Pathway.

The pantograph is designed to support the heavy center spool during all movement conditions while equalizing the movement of the bellows. The center gimbal ring allows the expansion joint to move laterally in the direction that is normal to the plane of the pantograph without causing binding of the pantographic linkage.

Slotted hinges are included to add mechanical stability to the expansion joint while limiting the movement of the bellows. Limit rods also limit bellows movement and provide pressure restraint in the event of an upset.

A stainless steel pointer and scribe lines on the slotted hinges indicate the bellows movement. This feature allows the end user to check to see if the expansion joint is moving properly while it is operating.

The bellows is oversized. This allows the liner inside the bellows to be the same size as the line pipe to minimize turbulence and catalyst erosion.

The pipe diameter transition was created by an expanding process that eliminates the need for circumferential welds. The alternative to expanded pipe is a welded conic. The local stress at the knuckle portion of the Senior Flexonics Pathway expanded transition is less than half the local stress that results from a welded conic design.

The covers are removable but also sealable in the event of a bellows failure. A purge connector is also included on the cover to facilitate seal welding in the event of bellows leakage.

The bellows are packed with a refractory blanket reinforced with knitted wire to eliminate intrusion of catalyst into the bellows liner cavity. The liner opening is sealed with a Senior Flexonics Pathway designed wire mesh seal system. However, purge connections are mounted on the shell of the expansion joint as a backup in the event that the packing is lost during operation.

To avoid cooling of the bellows below the condensation temperature of the media, insulation is installed between the bellows and the cover. Severe corrosion can result if standpipe bellows operate below dew point. To maximize the corrosion resistance of the bellows material, the bellows were annealed after forming.

The bellows are ply testable such that each ply is capable of handling the full design pressure and temperature. This feature provides a 100% bellows safety factor. A Senior Flexonics Pathway patented “red top” leak detector system is also included in the design although it is not visible in the photo. The red top indicator lets the operator know if there is a crack of any size in the inner ply, the outer ply or in the attachment weld of the bellows. If the red top indicates a crack has developed in any of these areas, the expansion joint can still operate with complete safety until the operator decides it is time to make repairs.

For more information about Senior Flexonics Pathway custom designs for FCC expansion joints, contact Senior Flexonics Pathway. Visit our web site at www. myej.com.