ASME B16.47 Series A Class 900 Blind Flange is essentially a solid steel disc without a center bore. Its sole function is to terminate a piping run, isolate a section of a pressure vessel, or block flow to allow down-stream maintenance. HT PIPE supply all different types and scales of flanges. Please feel free to contact us for further product information and pricing.
ASME B16.47: This standard governs large-diameter steel pipe flanges from NPS 26 through NPS 60.
Series A: Inherited from the old MSS SP-44 standard, Series A flanges are thicker, heavier, and utilize larger bolts compared to Series B (which derived from API 605). Series A is the go-to choice for high structural integrity and external piping loads.
Class 900: This is a high-pressure rating class. At ambient temperatures, a Class 900 carbon steel flange can withstand working pressures well above 2000 psi (approx. 150bar), depending on the exact material chemistry used.
Why Series A is Preferred Over Series B for Class 900 Blinds
When sourcing large-diameter blind flanges in North America, designers often weigh Series A against Series B. For a Class 900 rating, Series A holds a clear structural advantage:
Mass and Thickness: Series A flanges feature a significantly thicker cross-section. This thickness resists the severe bending moments exerted on a blind plate when under thousands of pounds of pressure per square inch.
Bolting Profile: Series A utilizes fewer, but much larger, bolts. Series B uses a high number of smaller bolts. In high-pressure Class 900 applications, handling and tensioning larger bolts provides a more robust, long-term gasket crush, reducing the risk of catastrophic joint relaxation.
ASME B16.47 Series A Class 900 Blind Flange Dimensions
