Why Standard Flanges not designed against Piping Load
Posted: 24 Apr 2010, 19:53
When a standard flange is rated for a certain pressure (usually the pressure we regard as INTERNAL DESIGN PRESSURE), it normally poses sufficient strength to resist the rated pressure load (INTERNAL DESIGN PRESSURE) plus substantial reserve strength to resist the PIPING LOAD. This reserve strength varies from flange to flange and is not known unless a Stress Analysis (Appendix II Calculation is one of the probable modes of Aanlytical Stress Analyses) is carried out. It is also highly dependent on the thickness of the connecting pipe when a bore of the flange is specified to be the same as that of the pipe.
In designing a Special Flange/Non-Standard Flange (normally Appendix II Flange), however, it is essential that some allowance be provided for PIPE LOAD. The allowance might be based either on the acual expected PIPE LOAD or on the LOAD that would give birth to a BENDING STRESS, equivalent to one half of the BASIC ALLOWABLE STRESS, at the connecting pipe. In any case care should be exercised in the final PIPING SYSTEM DESIGN to keep the PIPE LOAD from exceeding the allowance assumed.
Please visit the research papers as follows for better understanding of above topic. (Why Standard Flanges not designed against piping loads)
“Evaluation of Flanged Connections due to Piping Loads”
by D.L. Mckethan, Division Manager, Piping Mechanical Division
& L.C Pang, Principal Staff Engineer, M.W. Kellog Company, Houston, USA
In designing a Special Flange/Non-Standard Flange (normally Appendix II Flange), however, it is essential that some allowance be provided for PIPE LOAD. The allowance might be based either on the acual expected PIPE LOAD or on the LOAD that would give birth to a BENDING STRESS, equivalent to one half of the BASIC ALLOWABLE STRESS, at the connecting pipe. In any case care should be exercised in the final PIPING SYSTEM DESIGN to keep the PIPE LOAD from exceeding the allowance assumed.
Please visit the research papers as follows for better understanding of above topic. (Why Standard Flanges not designed against piping loads)
“Evaluation of Flanged Connections due to Piping Loads”
by D.L. Mckethan, Division Manager, Piping Mechanical Division
& L.C Pang, Principal Staff Engineer, M.W. Kellog Company, Houston, USA