# Dynamic Response of Drill Floor Considering Propagation of Blast Pressure Subsequent to Blowout
## 6 Conclusions  
The objective of the present study is to describe the blowout scenario and explosion cases, and then develop an improved application of blast pressure to the drill floor according to the propagation of blast pressure in an offshore drilling unit. The improved pressure application is compared with  
\begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Load Case**} & \multicolumn{3}{c}{**Material**} \\ \cline{2-4}  & **S235** & **S355** & **S460** \\ \hline Overall Peak & 4.38\% & 2.57\% & 1.93\% \\ Case-1 & & & \\ \hline Overall Average & 1.34\% & 0.36\% & 0.15\% \\ Case-2 & & & \\ \hline Group Peak & 1.90\% & 0.79\% & 0.49\% \\ Case-3 & & & \\ \hline Proposed & 0.81\% & 0.17\% & 0.00\% \\ Case-4 & & & \\ \hline \hline \end{tabular}
\end{table}
Table 11: Maximum strain for each load case and material.  
Figure 19: Strain profile of (**a**) frame S235 for each load case and (**b**) frame for load case-1 according to the material.  
maximum single, total average, and group pressure application. The inferences from the present study are summarized below.
* The characteristics of blast pressure propagation after ignition in gas dispersion due to blowout are described. The blast pressure value increases as the explosion propagates the gas volume within the drill floor.
* This study proposed an improved grouped blast pressure reflecting propagation, which captures the phenomenon of explosion in a more realistic manner. The maximum single method is a very conservative approach and could result in a heavy structure. The total average method is non-conservative and could therefore fail to catch higher pressure than the average. A group method is developed to make up for the above two methods, but it does not fully reflect the nature of explosion. The method proposed in this study captures the nature of the explosion and estimates the blast pressure accurately, therefore contributes to a safer and lighter blast resistant design for offshore facility structures, which are very sensitive to weight due to buoyancy and payload.
* Different grades of steels generally used in offshore structures are introduced and compared in terms of exposure to blast pressure. As the material for blast resistance, a low tensile material is considered favorable since it has sufficient ductility than high tensile ones. However, this study shows that high tensile material, which is widely used in offshore facilities from the viewpoint of strength, has advantage in strain as well.  
Conceptualization and project administration, J.-M.L.; analysis and writing, T.-K.K.; review and editing, S.-K.K. All authors have read and agreed to the published version of the manuscript.  
This work was supported by the R&D Platform Establishment of Eco-Friendly Hydrogen Propulsion Ship Program (No. 20006644, 20006632) funded by the Ministry of Trade, Industry & Energy (MOTIE, Korea). This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT) through GCRC-SOP (No. 2011-0030013).  
The authors declare no conflict of interest.