I am looking after maintenance of SRUs in our refinery. We had similar issues earlier in the SRUs. We were able to identify all the root cause and rectify all of them. Currently we are having no issues with sulfur rundown lines. Following are very important when it comes to avoiding solidification of sulfur:
1. Design and fabrication of sulfur jacketing lines.
2. Slope of all Sulfur rundown lines from condensers.
3. proper monitoring of steam traps.
4. Avoid refractory carry over to sulfur rundown lines.
5. Avoid water stagnation at the bottom of sulfur seal legs
6. proper insulation and proper sealing of insulation joints
7. Monitoring of steam inlet temperature
Apart from these, there were several other minute details which were corrected to avoid sulfur solidification. Rodding during initial start-up period is being done with chain pulley block arrangements which are comparatively much safer for workers.