In 1987 - 1988 LNG Industry had been introduced with a new methodology called HAZOP to assess a new design or an existing design for any potential of hazard. HAZOP stands for Hazard and Operability. The study starts with selecting study nodes using P&ID (Process & Instrument Diagram). For each nodes the team should ask questions from a combination of process parameter and deviation. List of parameters among others are temperature, pressure, level, flow, composition, contamination. While list of deviation, e.g: high, low, reverse, abnormality. By combining these the team for example would ask questions like "what are things that could cause this node (line or vessel) to experience high temperature". The team would then use their knowledge and experience, after checking the P&ID and other documents, to determine if there is any significant risk. They will then check if existing design can mitigate the risk. If not available, the team would record it in the list as things to be followed-up later.
I was assigned by Badak LNG Plant managment at that time to chair the HAZOP study for area Process, Utilities and Storage & Loading. You can imagine how long will it take to accomplish the task. I recall we took 6 months to complete the job. The core team consisted of 1 process engineer, 1 operation supervisor, 1 instrument engineer, 1 instrument maintenance. The others are assigned as needed basis, they are mechanical and rotating engineers, electrical engineer, civil engineer, and mechanical maintenance supervisor.