Study on Skirt Base Ring Reinforcement for Tailing of Vertical Vessels

EPC contractors / manufacturers design and use the lugs attached on the skirt for tailing of vertical vessels. To avoid the overstressing and deformation of the skirt base ring due to tailing load, the reinforcing beams attached inside the base ring may be considered. Since the design rules for tailing devices are not described in ASME BPVC Section VIII, the soundness of the tailing design could be left to the judgement of individual parties. In past projects, the deformation of the skirt base ring during lifting work at construction site occurred and gave huge impact on construction schedule and cost. As per the theoretical calculation for the design of the skirt base ring reinforcements, the beams are generally considered as “rigid” structure. Based on the results in this paper, it can be said that the base ring may be overstressed and largely deformed if the axial stiffness of the reinforcing beams is not properly taken into the consideration of tailing design, especially for large diameter vessels. This paper provides the basic concept and practical design consideration of the skirt base ring subject to tailing load by investigating the tendency of bending moment and residual plastic deformation of the skirt base ring with several types of reinforcing beam arrangement.