Answer: The structure of the pressure vessel is closely related to the safe use of the pressure vessel. An unreasonable structure often makes it difficult to ensure the welding quality or brings about excessive stress concentration and bending stress, which becomes an important cause of pressure vessel damage. In the past, the connection structure between the cylinder and the head did not meet the standards and specifications. Instead of butt joint, lap joint and fillet joint were used. The weld structure type was improperly selected or a prohibited structure was selected. Instead of double-sided welding, single-sided welding was used. The weld arrangement was unreasonable or the weld distance was less than the specified value. The head type was improperly selected, and an unreasonable head type was used. Instead of a convex head, a flat cover head was used. The manhole, hand hole, inspection hole, and pipe opening were improperly opened, and the size did not meet the requirements. The reinforcement was not reinforced or was insufficient. The support (column) or support type was improperly selected, resulting in local stress concentration, cracks, and endangering safety. The flange structure type did not meet the use requirements. Instead of a long-neck flange, a flange of other types was used. The sewage outlet was not opened, or the opening position was improper, which failed to achieve the purpose of sewage discharge, causing sewage blockage and serious corrosion. In addition, the stress concentration parts of some quick-opening door structures were improperly designed, and the safety interlocking device was not set or not used, resulting in explosion accidents. For this reason, these main structural parts should be inspected to ensure safety.
