R Style Oval Rings can be used only in Bottom Grooved Flanges. R Style Oval & Octagonal Rings are interchangeable with Flat Bottom Grooved Flanges. RX and R Style rings of Similar Nos are interchangeable . BX and RX Style rings are not interchangeable standard API 6A and ASME B 16.20. We are looking for queries from India especially from North India & South India.