Design of B16 Standard and Non-Standard Ring Type Joint Flange and Gasket

Abstract

Bolted flange joints using ring type joint (RTJ) gasket has been widely used in oil & gas industry especially for high pressure service less than and equals to 2500 psi or high temperature services. Recently performance of other types of gaskets, such as grooved metal and spiral wound gasket are increased and being reviewed, but RTJ is still a first option for many operators and designers. The flange and gasket design details are provided in ASME B16.5 and B16.47 and the details of the gasket and ring facing are provided in B16.20, however, field problem often occurs in construction site, especially the damage of the ring joint facing due to the overloading. Similar troubles have been reported in non-standard flange and when designing flange connection, additional attention should be paid in addition to the standard design procedure shown in ASME Sec.VIII div.1 Mandatory Appendix 2. To provide a guideline to design the flange joint and determine appropriate bolt load, detailed review and study was conducted. First, past troubles related to ring type joint are introduced, such as gasket coining into flange groove, and groove deformation of spacer component. Second, to clarify the root cause of such troubles, design of B16 flange, especially ring joint gasket size and facing geometry is reviewed and show gasket sizing and stress states varies with flange size and rating. A series of finite element analysis was performed, and analysis results are reviewed in terms of gasket stress, gasket contact pressure, groove stress and deformation. Finally, several recommendations on the determination of gasket size, flange groove dimension and initial tightening load are explained.