I have used refurbished vessels in the past. Prior to using them the maximum pressure that they could tolerate would be calculated by others. In addition, they would be inspected for corrosion by others. However, I have been involved in 2 kind of designs of pressure vessels as follows: Development of a “duty specification”. In this case I have given the design company the residence time that is required to complete the reaction along with the operating temperature and pressure. The residence time would be determined by laboratory or pilot plant studies. In this case, the design company would be responsible for +sizing the vessel, +studying potential side reactions, +sizing the safety valve for a case of a temperature runaway, +sizing the cooling system +as well as several other areas that are basically chemical engineering related. Confirming the mechanical integrity of the vessel as well as inspecting for corrosion. For this design work the owner should provide the engineering contractor with a Design Basis Memorandum that describes the reaction and how the safety valve system should work. The design company would then be responsible for all phases – chemical and mechanical and foundation of the design. Development of a complete process design package – In this case the operating company would be responsible for the items shown in red above. The design company would then be responsible for only the mechanical design. In either case, the design company would be responsible for the mechanical inspection of the vessel to be refurbished. This process design package should consist of vessel drawings including all nozzles and piping sizes. It should also include a discussion of potential runaway reactions and the cooling system. The selection of either of the approaches (“duty specification” or “process design package”) is a function of the desires of the operating company. It must be clearly delineated for the design company.
This case takes place in Pennsylvania and involves a massive explosion at a facility that specialized in the design and manufacturing of specialty chemicals primarily used for the production of advanced materials for high-end engineering applications. The explosion originated from a large chemical reactor during the production of a notoriously dangerous and volatile compound. The reactor system lacked a number of essential safeguards designed to contain the heat and pressure generated from the reaction, which led to runaway heating of the reactor’s structure. The configuration of the reactor was allegedly in violation of multiple safety codes and regulations at the time of the accident, and the resultant explosion killed several workers and caused millions of dollars in damage. Expert witnesses with specializations in forensic chemistry and explosives were retained for this case.
