This project is a bit special to us at Saba Metallurgical. A new client had a situation where the internal refractory was lost and a hemispherical shell section became overheated, bulged, cracked and then locally ruptured. No other engineering firms they contacted were willing to take on this difficult fitness-for-service. However, having a strong background in hydrogen damage, materials and fitness-for-service evaluation design tools, we were able to return the vessel back to service under FFS-1. We worked with another firm to produce a 3D laser scan of the damaged area for use in an FEA model. A cut out was made of the hydrogen cracking region and a flush patch installed in the field (and in the FEA model). Still outside this patch was shell distortion. FFS-1 FEA design methods and rules were followed to show the vessel was fit-for-service for an initial short duration to allow for monitoring of refractory stability. Now, the fitness-for-service certificate is renewed on an annual basis, with equipment inspection and document review performed during each renewal. This equipment, the center of this plant’s operation, has been operating successfully 6-years since this writing. Along the way, Saba Metallurgical has helped out with the redesign of their internal refractory, especially regarding localized refractory supports. Recommendations for external cooling and live/recorded infrared monitoring have been completed and maintained.
