Design Standards and Specifications
The design of pressure vessels must adhere to international and national standards to ensure safety and reliability. Widely adopted international standards include the ASME Boiler and Pressure Vessel Code: ASME Section VIII-1 applies to stationary vessels with design pressures up to 20 MPa; ASME Section VIII-2 applies to stationary vessels where specific pressure limits are not prescribed (though generally up to 70 MPa); and ASME Section VIII-3 applies to stationary metallic vessels typically operating above 70 MPa. In China, the GB/T 150 series of national standards is primarily followed.
Evolution of Design Principles and Methods
The theory of pressure vessel strength design is a discipline driven by failure analysis. In the early 19th century, design was merely a process of selecting wall thickness based on successful precedents. In 1915, the American Society of Mechanical Engineers (ASME) issued the world's first pressure vessel design standard, the *Boiler Construction Code* (ASME Section I). This introduced the concept of design based on elastic strength theory and established the "design-by-rule" method, which focused on static peak-strength failure modes. During the 1940s and 1950s, the recognition that different stress types-such as membrane stress and edge stress-contribute differently to failure led to the development of the "design-by-analysis" method based on stress classification. The advent of computers, finite element technology, and the nuclear power industry facilitated the establishment of modern analytical design techniques-exemplified by ASME Sections III and VIII-2-marking the shift toward analytical design approaches that account for multiple damage modes, including elastoplasticity and fatigue.
Manufacturing Technology and Quality Control
The design, manufacture, and inspection of pressure vessels involve the shared responsibilities of the user, the manufacturer, and the Authorized Inspector (AI). Manufacturing technology integrates expertise from various fields, including metallurgy, machining, welding, heat treatment, and non-destructive testing (NDT). Key technological advancements are evident in materials science (e.g., high-purity materials, media compatibility, and the use of higher-strength materials) and the widespread application of computer technologies (e.g., CAE, CAM, computer-controlled welding, and defect detection techniques such as Time-of-Flight Diffraction/TOFD ultrasonic scanning).