They also have a smaller bolt circle diameter than Series A flanges. Smaller bolt circle diameter results in less flange movement after installation. Both the A-series and B-series standards define raised face (RF) butt-weld and blind flanges, but only the A-series defines ring joint (RTJ) flanges from classes 300 to 900 in this standard. In terms of price, ASME B16.47 series A flanges are more expensive than ASME B16 47 series B flanges.