LITTLE P.ENG. FOR ENGINEERING CONSULTANCY SERVICES

Most flanges in ASME B31.3 piping systems are in accordance with the following listed standards: ANSI B16.1, Cast Iron Pipe Flanges and Flanged Fittings ASME B16.5, Pipe Flanges and Flanged Fittings ASME B16.24, Cast Copper Alloy Pipe Flanges and Flanged Fittings: Classes 150, 300, 600, 900, 1500, and 2500 ASME B 16.36, Orifice Flanges, Classes 300, 600, 900, 1500, and 2500 ASME B 16.42, Ductile Iron Pipe Flanges and Flanged Fittings, Classes 150 and 300 ASME B 16.47, Large D

Most blind flanges are in accordance with listed standards, such as ASME B16.5. When designing a blind flange, the rules of ASME BPVC Section VIII, Division 1, para. UG-34 apply. The procedure in ASME BPVC Section VIII includes consideration of the moment due to the flange bolts, so the required bolt load for boltup and operation must be determined per the flange design rules of Appendix 2 of ASME BPVC Section VIII, Division 1. #Little_PEng. Engineering Consultant Services #A

Most flanges arc in accordance with listed standards, such as ASME B 16.5, and for larger flanges, ASME B 16.47. Appendix L is provided in ASME B31.3 to cover aluminum Flanges because they are not included in ASME B16.5. When a custom flange is required, design by analysis is permitted by para. 304.5.1. ASME B31.3 refers to the rules for flange design contained in ASME BPVC Section VITI, Division 1, Appendix 2, but using the allowable stresses and temperature limits of ASME B

The flange components consisting of flange, gaskets, and bolts may have been adequately designed but their performance to specifications will be affected by assembly conditions. Flange Surface Finish Flange surface finish is critical to achieve the design-sealing potential of the gasket. Again, gasket-leak tightness is dependent upon its operating gasket stress. Flanges that are warped, pitted, rotated, and have incorrect flange gasket-surface finish will impair the leak tigh

Joint Stiffness It is important to recognize that the individual components of flanges, gaskets, nuts, and bolts operate together as a system. Gasket companies are continually fielding questions from concerned users about their ‘‘gasket’’ leakage. Gasket leakage is symptomatic of a broader problem. To focus exclusively on the gasket as the cause of the leakage fails to recognize that the flange joint operates as a system, and a systems approach should be used to design flange