As the name suggests, the ASME Boiler and Pressure Vessel Code (BPVC) sets standards for the design and fabrication of boilers and pressure vessels. Many industries require conformance with this code without exception and it also serves as the de facto standard for designs where no codes exist or none have been specified.
The BPVC contains several sections and section XIII deals specifically with pressure vessels. Section XIII has three divisions, two of which are more common. Divisions 1 and 2 provide mandatory requirements and non-mandatory guidance for design, fabrication and testing of pressure vessels exceeding 15 psi operational pressure. While both divisions cover similar tanks, Division 2 contains a set of alternative rules to the design-by-formula approach of Division 1 including provisions for the use of Finite Element Analysis (FEA) to determine the expected stresses that may develop during operation. Division 3 contains rules for pressure vessels exceeding 10,000 psi.
In contrast to Division 1, Division 2 provides for a design-by-analysis approach. Stress analysis can be performed using FEA which – when used properly by technically knowledgeable analysts who understand not just the underlying physical models but both the power and limitations of an FEA simulation as well – allows a much more in-depth understanding of how stresses develop in the vessel structure.
For example, some vessels may experience repeated thermal stress cycles due to the way they are operated which can eventually cause fatigue failure. Using the rules of Division 2 combined with a thermal simulation followed by an FEA stress analysis, which predicts the thermally induced stresses, a safe operating number of cycles can be established. Other parts of the Division 2 rules permits this powerful FEA approach as well. There are many considerations that must be accounted for when tackling an FEA analysis and we understand the inputs and setup required to generate meaningful results. Please see our Finite Element Analysis section for more detail (link).