What is the difference between ASME B16.5 and B16.47 flanges

American national standards ASME B16.5 and B16.47 together cover flanges up to NPS 60.ASME B16.5 standard covers steel pipe flanges and flanged fittings from NPS 1/2 through NPS 24 Metric/Inch in pressure class 150 to class 2500.ASME B16.47 standard for pipe flanges in sizes NPS 26 through NPS 60 and in ratings Classes 75,150,300,400,600,and 900.ASME B16.47 covers two series of flanges,ASME B16.47 Series A which is equivalent to MSS SP-44 (the 1996 Edition of MSS SP-44 complies with B16.47 tolerances),and ANSI/ASME B16.47 Series B which is equivalent to API 605 (API 605 is now cancelled).

American national standard ASME B16.5 and B16.47 cover flanges up to NPS 60.ASME B16.5 standard includes steel flanges and flanged fittings for pressure class 150 to 2500 and size range from NPS 1/2 to NPS 24 metric/inch.ASME B16.47 standard for pipe flanges in sizes NPS26 to NPS60 and in ratings class 75,150,300,400,600 and 900.ASME B16.47 standard includes two flange series,ASME B16.47 series A standard is equivalent to MSS SP-44 (the 1996 Edition of MSS SP-44 complies with B16.47  tolerance),ASME B16.47 series B standard is equivalent to API 605 (API 605 has been cancelled).

ASME B16.5 ASTM A105N RTJ weld neck flanges

ASME B16.5 ASTM A105N RTJ weld neck flanges

What is the difference between ASME B16.5  flange and ASME B16.47 flange?

As can be seen from the figure below,ASME B16.5 standard contains more types of flanges than ASME B16.47 standard,and ASME B16.47 standard only includes weld neck flange and blind flange.

ASME B16.47 Series A flanges are thicker,heavier,stronger and more costly than ASME B16.47 Series B flanges of the same size and rated pressure,and therefore bear more external loads than the ASME B16.47 Series B flanges.ASME B16.47 Series B flanges require more but smaller fasteners (bolts and nuts) than Series A flanges,and the bolt circle diameter is also smaller than series A flanges.The smaller bolt circle diameter results in less flange movement after installation.

Summary of flange sizes specified by ASME B16.5 and B16.47 standards:

Flange Type Specifications
ASME B16.5 ASME B16.47 Series A(MSS SP-44) ASME B16.47 Series B(API 605)
Nominal Pipe Size
<NPS 26 ≥NPS 26 ≥NPS 26
Nominal Pressure(Class)
Class (lb) Class (lb) Class (lb)
Weld Neck Flange 150-2500 150-900 75-900
Slip on Flange 150-1500
Blind Flange 150-2500 300-900 300-900
Lap Joint Flange 150-2500
Socket Weld Flange 150-1500
Threaded Flange 150-2500
Flat/raised Face As above As above As above
Ring Joint Face 150-2500 300-900 300-900
Other Face 150-2500


  1. MSS SP-44 flanges are designated Series A flanges in ASME B16.47.It also covers flanges in the range NPS 12 to 24,
    these being equivalent to ASME B16.5 flanges in the same range (except for the addition of NPS 22 in MSS SP-44).
  2. API 605 has been cancelled. API 605 flanges are designated Series B flanges in ASME B16.47. Ranges quoted are based on ASME B16.47 Series B.
  3. Dimensions not covered in this summary
ASME B16.47 ASTM A105 blind flanges

ASME B16.47 ASTM A105 blind flanges

Haihao Group can manufacture both types of ASME B16.5 and B16.47 flanges,we supply forged flanges in different materials such as carbon steel,stainless steel,alloy steel.We also can supply forged flanges according to other standards like:ANSI/ASME B16.36,ANSI/ASME 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.

Carbon steel:ASTM A105,A350 LF2,SS400,P235GH,P250GH,C22.8,Q235,20#,16Mn.

Stainless steel:ASTM A182 F304,F304L,F316,F316L,F321,F347,F310,F44,F51 etc.

Alloy steel:ASTM A694 F42,F46,F52,F56,F60,F65,F70,A182 F5,F9,F91,F12,F11,F22 etc.

This is all the difference between ASME B16.5 flanges and ASME B16.47 flanges.If you want to know more about our high pressure forged flanges,please email us:sales@haihaogroup.com


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