In general Section I of the ASME Boiler Code was originally developed for industrial boilers through to sub-critical boilers operating at relatively low temperatures and pressures under steady state conditions. Current and future boilers do and will operate at higher temperatures and pressures under cyclic loading requiring a more detailed assessment and examination to ensure safe and reliable operation.

Design by Analysis (DBA) methods will be fundamental to the assessment process for key boiler components. It is intended that the Code will incorporate several DBA methods, ranging in complexity, to allow the user some flexibility to select the method appropriate to the design conditions.

The methods currently being considered include an elastic approach based on Section VIII Division 2, a simplified inelastic approach, an inelastic approach based on the Omega method from API 579, the Section VIII Division 2 Code Case 2843 based on the Section III Part NH rules utilizing the strain deformation method and a new Section III Code Case based on the EN 13445 approach.

This paper will look at the key aspects of the methods and highlight the limitations of each.

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