30 TONNE EXPANSION JOINT
FOR FLUID CATALYTIC CRACKING
This customized expansion joint was designed, manufactured and tested for a fluid catalytic unit located in an oil refinery complex. It is installed in the pipe bend above the reactor and at an approximate height of 100 meters. This FCC expansion joint weighs in at 30 tonnes due to the conditions requiring a large expansion joint, both in terms of length and dimension.
Customized FCC expansion joint
Traditionally, most FCC expansion joint designs are made strictly according to standards and client specified design codes. For this 30 tonne expansion joint the client specially requested that the inside should be easy to access. For that reason, a man hole on the FCC expansion joint was made in order to facilitate easy access and inspection of the unit during maintenance. This man hole was custom-made with a removable cover to save space and simplify transportation. As the man hole cover is very heavy, due mainly to the refractory lining, a smart opening and closing mechanism on the man hole was made – making the task of lifting and opening convenient and simple. A customized approach in regards to the bellows inner soft insulation was required due to the high risk of damage to the bellows “packing” by aggressive and abrasive media. Typically, FCC expansion joints are equipped with one metallic rope acting as an extra sealing for the inner ceramic wool insulation. This prevents small particles from entering and settling in the bellow. The customer was concerned that the large lateral movements would shift the rope from its original position and thereby generate a gap through which the media could penetrate and damage the bellow. In order to solve this a double rope solution was chosen. In this way the second cable is placed slightly lower on the inner sleeve opening, thereby sealing any potential gap which might occur during the lateral displacement of the unit.
AXENS & ASME
The expansion joint is calculated according to Axens standards and furthermore ASME. Belman has vast experience in the design of expansion joints according to different standards and design codes. Due to this substantial experience Belman can easily customize the design and production to any required design code and/or standard.
2-ply testable bellows & leak detection
Leak monitoring was also specified amongst the requirements. For that reason, pressure gauge devices are installed at the expansion joint to indicate any issues with the bellows during operation. Further, the expansion joints are specified with “packed” bellows designed as 2 ply testable bellows with redundant construction. With this construction the single layer would be able to carry the full load in the event of operating alone. In other words, if one of the layers fails, the other ply would be able to secure operational safety of the expansion joint until a scheduled shutdown.
Design parameters of the FCC expansion joint
The FCC expansion joint have the following design parameters:
Quantity: 1 pcs • Dimension: DN 1250 • Length: 10000 mm • Medium: Flue gas • Lining: Resco • Design temperature: 350°C • Design pressure: 4,6 barG • AX: +0/-70 mm • LA: +/-150 mm • AN: +/-0,5° • Bellows: 2.4856 (Inconel 625 (LCF)) • Welding ends, middle pipe: SA-516 gr. 70