What diameter does a super-large pressure vessel need to have to be considered such?

Generally speaking, ultra-large pressure vessels refer to those with a diameter or length that is too great to be transported in their entirety by road or rail, depending primarily on the transportation regulations of various ** and regions. The specific dimensions will vary depending on the region and mode of transportation. For example, in some **regions, if the size of a pressure vessel exceeds the limits set for road or rail transportation (for instance, in some places a special transportation permit is required if the width exceeds 3.5 meters), it may be considered an oversized pressure vessel. As for the shape issue you raised, if a pressure vessel cannot be transported as a whole due to its special shape (such as T-shaped), it can generally also be considered an ultra-large pressure vessel. As for the on-site welding of ultra-large pressure vessels, special welding qualifications and relevant safety operation permits are generally required. The specific document requirements vary by region and **. When carrying out on-site welding operations, it is essential to strictly adhere to the relevant welding procedures and safety regulations in order to ensure the safety and quality of the work. In China, on-site assembly welding generally requires certain qualifications as a welding engineer or welder, and it is also necessary to comply with the safety regulations for pressure vessels in order to ensure the safety of welding operations. In general, manufacturing and installing ultra-large pressure vessels is a very stringent process that requires appropriate qualifications and experience. .