Abstract
This paper is an introduction to Allowable Stress Design (ASD-Stress), Allowable Strength Design (ASD) and Load and Resistance Factor Design (LRFD) and their application to pressure equipment. Many new and experienced mechanical engineers have little or no previous exposure to LRFD which results in misunderstandings between mechanical and structural engineers regarding the meaning and interpretation of loads (particularly wind and seismic). Some history regarding the Specification for Structural Steel Buildings (ANSI/AISC 360) will be provided noting how changes in the specification over the years have influenced the design codes for pressure vessels and piping. Additionally, some background will be presented regarding the load combinations and loads provided by different versions of ASCE 7 otherwise known as the Minimum Design Loads and Associated Criteria for Buildings and Other Structures. The design methodologies, loads, load combinations and associated factors will be discussed and demonstrated how they should be applied to the design of pressure vessels and piping. Lastly, design and serviceability examples will be provided.
