In the summer of 2018 Flextech Industries was awarded a contract to build an expansion joint for a Fluid Catalytic Cracking Unit (FCCU) destined for a large refinery in the midwest USA. Expansion joints for these units, known as ‘cat crackers’ are integral for refinery production, being used in the conversion of heavy distillates into lighter more valuable products, such as gasoline, kerosene, and diesel.
These ‘cat crackers’ are operated at high temperatures, often under very high pressures, resulting in large axial movements, and the media can be both very erosive and corrosive – making these FCCU one of the more complex and involved expansion joints to engineer and manufacture. Flextech Industries built this expansion joint in accordance with the Expansion Joint Manufactures Association, Inc (EJMA) standards, as well as ASME B31.3 Appendix X – fulfilling all necessary design, testing, and 3rd party NDT requirements.
The completed unit internal refractory lining with stainless steel anchors to limit the shell temperature remains within design limits – classifying this build as a ‘Cold Wall’ design. The exterior / frame of the unit also incorporated a large pantographic linkage system, ensuring axial movements are taken up equally by each bellows (in case of vertical installation where the weight of the unit may prevent even movement), as well as rolled exterior channel to assist with transportation and rolling of unit during refractory lining. The bellows were built in a twin-ply manner, but in such a way so each ply was designed for full operating conditions – this is referred to as ‘multi-ply redundancy.’ A passive pressure monitoring system was also incorporated into the bellows design. This passive pressure monitoring system was designed to give the maintenance team a visual indication if there was a failure. Fabrication of the unit was completed in under 12 weeks total, including all 3rd party NDT requirements, testing of the expansion joint, and refractory lining.
To-date this is one of the most integrated and complex joints Flextech Industries has completed, adding valuable experience to both our engineering and design, and production teams.