# Experimental and Numerical Predictions of Cryogenic Leakages in Welded Steel Plates
## 5 Conclusions  
In the present study, we conducted an experimental and numerical investigation of the cryogenic leakage on a plate structure of AH36-grade steel that contained welded joints. To achieve this, a welded plate was exposed to liquid nitrogen to simulate a cryogenic leakage condition. In addition, a three-dimensional finite element model was developed to simulate the FCAW process and the cryogenic leakage process. Based on the results obtained from this work, the following conclusions were drawn.  
* When the plate inside of the trough was submerged in LN\({}_{2}\), it cooled rapidly to the same temperature as the LN\({}_{2}\) and experienced significant thermal contraction due to the remarkable temperature reduction.
* After approximately 650 s, the thermocouples located outside of the trough measured approximately \(-75\)\({}^{\circ}\)C and \(-25\)\({}^{\circ}\)C, depending on their location.
* Due to the sudden thermal shock, the strain in both directions varied in a similar way and fluctuated considerably during the first 300 s of cryogenic liquid application.
* The residual stress of the weldments as measured in relation to the distance of the weld center line showed good agreement between the experimental and FEM approach.
* Although there was a relative difference in the results, the experiment and numerical simulation results for temperature and stress distribution obtained showed a similar trend.  
Ship structures, which are made up of thousands of types of equipment, require a welding process for their fabrication and assembly. Therefore, it can be said that the welding process is a very important production technology in the shipbuilding industry. Eco-friendly ships that use cryogenic liquefied gases, such as LNG and liquid hydrogen (LH2), have received considerable attention in shipbuilding. In the present study, the effect on welds of leakage of the cryogenic liquid gas was analyzed. The results could be used in the ship design stage adopting welded structures as a basic database.  
Conceptualization, D.H.K. and L.T.D.; methodology, K.-B.P. and Y.-H.C.; investigation, J.-H.K. and S.-K.K.; writing--original draft preparation, D.H.K., L.T.D. and K.-B.P.; resources, J.-H.K. and J.-M.L.; writing--review and editing, Y.-H.C. and S.-K.K. All authors have read and agreed to the published version of the manuscript.  
Figure 16: Validation between FEA and experiment.  
**Funding:** This work was supported by the Korea Institute of Energy Technology Evaluation and Planning (KETEP) and the Ministry of Trade, Industry & Energy (MOTIE) of the Republic of Korea (2022400000090). This research was supported by the Development and Demonstration of On-Board Marine Debris Disposal Modules Program of the Korea Institute of Marine Science & Technology Promotion (KIMST) funded by the Ministry of Oceans and Fisheries (KIMST-20220494). This work was supported by the R&D Platform Establishment of Eco-Friendly Hydrogen Propulsion Ship Program (No. 20006644) funded by the Ministry of Trade, Industry & Energy (MOTIE, Korea).  
**Institutional Review Board Statement:** Not applicable.  
**Informed Consent Statement:** Not applicable.  
**Data Availability Statement:** The data presented in this study are available on request from the corresponding author.  
**Conflicts of Interest:** The authors declare no conflict of interest.