# Structure Analysis of the Fractionator Overhead Vapor Line of a Delayed Coker Unit
## 4 Conclusions
### Main Findings  
From the analysis results, the following 12 points may be drawn:  
1. The static stress is larger when the pipelines are connected.
2. The first four modes of the pipeline vibration are primarily affected by the vibration of the 30\({}^{\prime\prime}\) main pipe while the fifth, and the sixth modes are primarily affected by the vibration of the smaller pipes.
3. For the cases of a magnitude 1 earthquake (parallel mode) and a magnitude 2 wind, the maximum harmonic response stresses occur at the same locations.
4. The maximum harmonic response stresses for various vibration modes occur at the support positions of 30\({}^{\prime\prime}\) main pipe, the intersection positions of the 24\({}^{\prime\prime}\) pipes, and the 30\({}^{\prime\prime}\)-to-24\({}^{\prime\prime}\) reducers, or the intersection positions of the 24\({}^{\prime\prime}\) pipes and the 20\({}^{\prime\prime}\) pipes.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline  & \multicolumn{3}{c}{**Resistance to Fatigue**} \\ \hline - & **Pipelines Connected** & **Pipelines Unconnected** & **Better Case** \\
**Wind** & up to magnitude 13 & up to magnitude 13 & equal \\
**Earthquake** & up to magnitude 5(+) & up to magnitude 6(\(-\)) & unconnected \\ \hline \multicolumn{3}{c}{**Resistance to yielding (permanent deformation)**} \\ \hline - & **Pipelines connected** & **Pipelines unconnected** & **Better case** \\
**Wind** & up to magnitude 17 & up to magnitude 17 & equal \\
**Earthquake** & up to magnitude 6(+) & up to magnitude 7 & unconnected \\ \hline \hline \multicolumn{3}{c}{**Resistance to fracture**} \\ \hline - & **Pipelines connected** & **Pipelines unconnected** & **Better case** \\
**Wind** & up to magnitude 17 & up to magnitude 17 & equal \\
**Earthquake** & up to magnitude 7 & up to magnitude 7 & unconnected \\  & (1718 gal (17.18 m/s\({}^{2}\))) & (2236 gal (22.36 m/s\({}^{2}\))) & unconnected \\ \hline \hline \end{tabular}
\end{table}
Table 7: Summary of the analysis results.  
5. Two of the positions for the maximum harmonic response stresses are shifted from the 30\({}^{\prime\prime}\) main pipe to the 24\({}^{\prime\prime}\) pipes after the pipelines are connected.
6. In terms of the wind effect, the pipelines connected or unconnected can both withstand a moderate typhoon of magnitude 13 without fatigue damage.
7. In terms of the seismic effect, the pipelines connected can withstand a strong earthquake of magnitude 5(+) without fatigue damage, while the pipelines unconnected can withstand a very strong earthquake of magnitude 6(\(-\)) without fatigue damage, which is better than the pipelines connected.
8. Under the action of a magnitude 17 severe typhoon, the stresses for pipelines connected or unconnected are both lower than the yield strength and the UTS. There is no danger of immediate damage in terms of the wind effect.
9. The pipelines connected or unconnected can both withstand magnitude 7 earthquakes up to accelerations of 1718 gal (17.18 m/s\({}^{2}\)) and 2236 gal (22.36 m/s\({}^{2}\)), respectively, without exceeding the UTS.
10. The pipelines unconnected are slightly better than the pipelines connected in terms of earthquake resistance.
11. From the previous study [26] and the present study, the primary cause of the pipeline abnormality is the asymmetry of the flow development, which is not closely connected with the pipeline structure.
12. The methods for analyzing the wind effect and the seismic effect used in this study can be applied to other equipment to evaluate its operation safety under the action of wind or earthquake.