ASME B16.47 covers pressure–temperature ratings, materials, dimensions, tolerances, marking, and testing for pipe flanges in sizes NPS 26 through NPS 60.
Included are flanges with rating class designations 75, 150, 300, 400, 600, and 900 with requirements given in both SI (Metric) and U.S. Customary units, with diameter
of bolts and flange bolt holes expressed in inch units.
This Standard is limited to
(a) flanges made from cast or forged materials.
(b) blind flanges made from cast, forged, or plate materials.
Also included in this Standard are requirements and recommendations regarding flange bolting, flange gaskets, and flange joints.
ASME B16.47 provides two series of flange dimensions.
Series A specifies flange dimensions for general use flanges. Series B specifies flange dimensions for compact flanges that, in most cases, have smaller bolt circle diameters than Series A flanges.
These two series of flanges are, in general, not interchangeable. The user should recognize that some flanged valves, equipment bolted between flanges, and flanged equipment may be compatible with only one series of these flanges.
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ASME B16.5 |
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. It covers pressure-temperature ratings, materials, dimensions, tolerances, marking, testing, and methods of designating openings for pipe flanges and flanged fittings. |
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ASME B16.47 |
For bigger sizes, ASME B16.47 standard covers pressure-temperature ratings, materials, dimensions, tolerances, marking, and testing for pipe flanges in sizes NPS 26 through NPS 60 and in ratings Classes 75, 150, 300, 400, 600, and 900. |
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ASME B16.47 series A |
ASME B16.47 series B |
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MSS SP-44 flanges are designated as ASME B16.47 Series A flanges |
API 605 flanges are designated as ASME B16.47 Series B flanges |
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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. |
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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. |
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From a commercial point of view, ASME B16.47 Series A flanges are more expensive than ASME B16 47 Series B flanges. |
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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. |
What is the difference between ASME B16.47 and 16.45 Flanges?
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. It covers pressure-temperature ratings, materials, dimensions, tolerances, marking, testing, and methods of designating openings for pipe flanges and flanged fittings. Two very important flanges such as weld neck flange and blind flanges are very commonly used in piping systems. The term "B16.5" or "B16 5" is used interchangeability and refers to same standard. However, the standard ASME B16 5 (ANSI B16 5) only covers size up to 24 inches. For bigger sizes, ASME B16.47 standard covers pressure-temperature ratings, materials, dimensions, tolerances, marking, and testing for pipe flanges in sizes NPS 26 through NPS 60 and in ratings Classes 75, 150, 300, 400, 600, and 900.
Conclusions:
Standard weld neck, slip on, blind etc. flanges are covered by standard B16.5 for sizes up to 24" nominal pipe. Sizes 26" and bigger are covered by B16.47 series A or series B for weldneck and blind flanges. Series A flange is heavier, thicker and cost more whereas series B flange has more bolt holes and is lighter cheaper than series A. API605 flange and series B flanges are same thing.
See documents below for comparison of flange sizes in two main standards (B16.5 and B16.47)
Flange Dimensions as per ASME B 16 5 standard for 150# Welding Neck Flange, Blind Flange, Slipon, Socketweld & Lapjoint flange
Flange Dimensions as per ASME B16 47 series A standard for 150# weldneck and blind flange
Flange Dimensions as per ASME B 16.47 series B standard for 150# weld neck and blind flange
