The distillation process, which is the most widely used process in petrochemical complexes and chemical products manufacturing, has a wide variety of separation systems, equipment structures, and operating methods, resulting in many troubles. While many companies have accumulated know-how on these problems, it is often not sufficiently transferred to the next generation. In this symposium, we will introduce troubles in the distillation processes and their solutions. In addition, gas absorption processes will be covered. We will discuss on troubleshooting, including preventive approaches.