The design of bolted joints in pressure vessels is frequently accomplished using design by rule procedures governing flange thickness, hub transitions, structural reinforcements, etc.  In some situations it may be preferable to undertake design by analysis.  Such cases may include non-uniform loading of the joint, interaction with adjacent components, or when the joint geometry does not correlate well to standardized designs.  The work presented here springs from efforts to improve standards governing design by analysis for bolted pressure retaining joints.  When a group of experienced analysts undertook simulation of such joints it was discovered that each brought assumptions and practices that led to much wider than expected variations between models.  Prior published work was also found to incorporate assumptions that are demonstrated to have non-negligible influence on the outcomes.  Results will be presented for a range of sizes and pressure classes, demonstrating the sensitivity of the results to certain modeling decisions.  Topics will include dimensions and blends that are not controlled in codes and standards, methods of representing bolt loads, and approaches and limitations of representing gaskets.  Results will be presented from 2D and 3D linear elastic models, and will also compare the predicted onset of gross plastic deformation for elastic plastic and elastic perfectly plastic material models.  An initial assessment of scalability of results and trends across sizes and pressure classes will also be discussed, illustrating that caution should be taken applying conclusions drawn from one size to another size or rating.  The goal of the work is not to present a ‘best practice’ for analysis, but rather to increase awareness of the issues and encourage analysts to verify their assumptions before proceeding with design by analysis work.


Impact of Modeling Decisions on Simulations of Bolted Joints

Division / Sponsors: 
Pressure Vessels & Piping (PVP)


Paper Proceedings: https://asmedigitalcollection.asme.org/PVP/PVP2020/volume/83815

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