What is the difference between ASME B16.47 Series A and Series B flanges

ASME B16.47 is a standard for large diameter steel pipe flanges sized from NPS 26 through NPS 60.The ASME B16.47 flanges can divided into ASME B16.47 series A flange and ASME B16.47 series B flange for blind flange and weld neck flange.Series A flange was known as MSS SP 44,Series B flange was also formerly known as API 605 flange.

ASME B16.47 ASTM A105 blind flanges

ASME B16.47 ASTM A105 blind flanges

What is the difference between ASME B16.47 Series A(MSS SP-44) and Series B (API 605) flange?

Generally speaking,ASME B16 47 Series A flanges are much thicker,heavier and stronger than Series B flanges in the same size and pressure rating thus can withstand more external loading than Series B type. ASME B16.47 Series B flanges need more but smaller fasteners (bolts & nuts) than Series A flanges and have a smaller bolt circle diameter than that of Series A flanges. The smaller bolt circle diameter results in less flange movement after installation. Both Series A and Series B standards define weld neck flanges and blind flanges in raised face type (RF) but only Series A defines ring type joint (RTJ) flanges from Class 300 through Class 900 within this standard. From a commercial point of view, ASME B16.47 Series A flanges are more expensive than ASME B16 47 Series B flanges.

Most piping users or designers may choose Series A flanges for the new pipeline or equipment.But if you are doing some refurbishment, replacement job or non-critical piping design,Series B flanges are more popular.

Pressure specification for ASME B16.47 Series A and Series B flanges:

ASME B16.47 Series A Weld Neck Flange RF (MSS SP-44)
150LBS 300LBS 400LBS 600LBS 900LBS 
ASME B16.47 Series A Weld Neck Flange RTJ (MSS SP-44)
  300LBS  400LBS  600LBS 900LBS 
ASME B16.47 Series A Blind Flange RF (MSS SP-44)
150LBS 300LBS 400LBS 600LBS 900LBS 
  ASME B16.47 Series A Blind Flange RTJ (MSS SP-44)
300LBS 400LBS 600LBS 900LBS
ASME B16.47 Series B Weld Neck Flange RF (API 605)
75LBS 150LBS 300LBS 400LBS 600LBS 900LBS
ASME B16.47 Series B Blind Flange RF (API 605)
 75LBS  150LBS  300LBS  400LBS  600LBS  900LBS

Haihao Group can supply ASME B16.47 Series A and Series B weld neck flanges and blind flanges,we also can supply other types forged flanges such as slip on flange,flat flange,socket weld flange,lap joint flange,threaded flange,long weld neck flange,orifice flange,spectacle blind flange,etc.We produce the forged flanges in different standards such as ANSI/ASME B16.5,ASME/ANSI B16.36,ASME/ANSI B16.48,AWWA C207,API 6A&6B&6BX,DIN 2527,DIN 2573,DIN 2576,DIN 2631,DIN 2632,DIN 2633,DIN 2634,DIN 2635,DIN 2566,DIN 2642,EN 1092,BS 4504,JIS B2220,GOST 12820,GOST 12821,SABS 1123,AS 1219 etc.If you want to know more about forged flanges,please email us:sales@haihaogroup.com


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