Selecting the Optimum Bolt Assembly Stress: Influence of Flange Type on Flange Load Limit

Author(s):  
Warren Brown

In previous papers, practical limits on the maximum applied load for standard ASME B16.5 and B16.47 carbon steel, weld neck pipe flanges were examined. A new code equation for the tangential (hoop) stress at the small end of the hub for a weld neck flange was developed to facilitate calculation of the limits using elastic analysis. The results were verified against elastic-plastic Finite Element Analysis (FEA). In this paper, the work is extended to include other flange configurations, including loose ring flanges, slip-on flanges and flat plate flanges. This paper is a continuation of the papers presented during PVP 2006 and PVP 2007 (Brown [1, 2]) and it extends the scope of the proposed methodology for determining flange stress limits in determining the maximum allowable bolt load for any given flange size and configuration.

Author(s):  
Warren Brown

In previous papers, practical limits on the maximum applied load for standard ASME B16.5 and B16.47 carbon steel, weld neck and slip-on pipe flanges were examined. A new code equation for the tangential (hoop) stress at the small end of the hub for a weld neck flange and new flange factors for a slip-on flanges were developed to facilitate calculation of the limits using elastic analysis. The results were verified against elastic-plastic Finite Element Analysis (FEA). In this paper, the work is extended to include other flange materials and verification is once again performed against elastic-plastic FEA. This paper is a continuation of the papers presented during PVP 2006, PVP 2007 and PVP 2008 (Brown [1–3]) and it extends the scope of the proposed methodology for determining flange stress limits in to any given flange material, size and configuration.


Author(s):  
M. Fahed ◽  
I. Barsoum

Carbon steel pipelines are renowned for their long-term resistance to the hydrostatic pressure of the transported fluid. Nevertheless, failure of carbon steel pipes can be catastrophic if not predicted or mitigated properly. One of the most common failure causes in carbon steel pipelines is corrosion of the pipeline inner and outer surfaces. The corrosion on pipeline walls will eventually lead to severe loss of material to a point which will cause complete loss of pipeline integrity. The study will assess the burst pressure of predefined internal corrosion-defected carbon steel pipelines through finite element analysis. The mechanical response of the host carbon steel pipeline is empirically estimated. A set of corrosion defect geometrical sizes, such as depth width and length to be considered is carefully developed. Accordingly, a parametric study considering the developed set of defect geometrical parameters, as well as the mechanical response of the pipe material, is conducted. The parametric study is performed through finite element analysis to investigate the influence of the highlighted parameters to the overall burst pressure of the pipe. Based on the results from parametric study of corrosion-defected carbon steel pipelines, the Buckingham π-theorem modelling approach is used to derive an analytical closed-form expression to predict the burst pressure of defected pipes containing internal corrosion defects of an arbitrary size.


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