STANDARD · ASME-B16-47-A

ASME B16.47 Series A Flange Dimensions

ASME B16.47-2025 · ASME B16.47 Series A

ASME B16.47-2025North America, Middle Eastpressure class

ASME B16.47 covers large-diameter flanges from NPS 26 to NPS 60. Series A preserves the former MSS SP-44 dimensions and is the series most often specified for large-bore oil and gas, water and process piping.

Series A and Series B use different outside diameters and bolt patterns for the same size and class, so the series must be stated on the purchase order. A Series A flange will not bolt to a Series B flange, and neither will bolt to an ASME B16.5 flange of the same nominal size. B16.47 covers weld-neck and blind flanges only — slip-on flanges above NPS 24 are made to drawing — and Class 900 is published up to NPS 48.

Base materialASTM A105

Size notationNPS (inch)

Material options5 groups

Reference data5 topics

DIMENSIONS

Dimension tables

One row per specification. Open a size for the drawing, pressure ratings and printable A4 sheet.

Weld Neck 84 Blind 84

Weld Neck: Butt-welded to the pipe with a tapered hub; used for high pressure, high temperature and cyclic service. 84 specifications.

12 specifications

Size	Rating	Outside Ø D	Thickness C	Raised face D2	Bolt circle K	Bolting	Hub A	Length H	Weight
26″DN650	Class 900	1086	139.7	749	952.5	20 × Ø73	775	286	692 kg	Spec sheet
28″DN700	Class 900	1168	142.7	800	1022.4	20 × Ø79.4	832	298	821 kg	Spec sheet
30″DN750	Class 900	1232	149.4	857	1085.8	20 × Ø79.4	889	311	962 kg	Spec sheet
32″DN800	Class 900	1314	158.8	914	1155.7	20 × Ø85.7	946	330	1154 kg	Spec sheet
34″DN850	Class 900	1397	165.1	965	1225.6	20 × Ø92.1	1006	349	1347 kg	Spec sheet
36″DN900	Class 900	1460	171.5	1022	1289	20 × Ø92.1	1064	362	1540 kg	Spec sheet
38″DN950	Class 900	1460	190.5	1099	1289	20 × Ø92.1	1073	353	1535 kg	Spec sheet
40″DN1000	Class 900	1511	196.9	1162	1339.8	24 × Ø92.1	1127	363	1642 kg	Spec sheet
42″DN1050	Class 900	1562	206.2	1213	1390.6	24 × Ø92.1	1176	371	1796 kg	Spec sheet
44″DN1100	Class 900	1648	214.3	1270	1463.5	24 × Ø98.4	1235	391	1950 kg	Spec sheet
46″DN1150	Class 900	1734	225.6	1334	1536.7	24 × Ø104.8	1292	411	2105 kg	Spec sheet
48″DN1200	Class 900	1784	233.4	1384	1587.5	24 × Ø104.8	1343	419	2259 kg	Spec sheet

REFERENCE

Pressure ratings, materials and tolerances

Transcribed from ASME B16.47-2025 with table and page references.

Pressure-temperature ratings

ASME B16.47-2025 pressure–temperature ratings (Group 1.1)

Table 3 (SI, bar) and Table 3C (U.S. customary, psig) of ASME B16.47-2025 give the maximum working pressure o…

Open reference Material groups

ASME B16.47-2025 material groups (Table 1)

ASME B16.47-2025 sorts every permitted flange material into a numbered group, and the group number — not the …

Open reference Tolerances

ASME B16.47-2025 flange tolerances (Section 7)

Section 7 of ASME B16.47-2025 sets the permissible manufacturing deviations for large-diameter flanges: raise…

Open reference Marking

ASME B16.47-2025 marking requirements (Section 4)

Section 4 of ASME B16.47-2025 defines the identification markings that must appear on every large-diameter fl…

Open reference Edition changes

ASME B16.47-2025 changes and record numbers

ASME B16.47-2025 was approved by the American National Standards Institute on 4 March 2025 and issued on 30 M…

Open reference

How to read the pressure class

Series A follows the former MSS SP-44 dimensions. Ratings are ASME classes 150, 300, 400, 600 and 900, with allowable pressures read from the B16.47 pressure–temperature tables for the material group and design temperature.

Edition and verification

Dimension values on this page have been checked against ASME B16.47-2025 (SI tables, cross-checked against the U.S. Customary tables). The 2025 edition prints exact metric equivalents of the inch dimensions rather than the old 5 mm-rounded values (for example 36.50 in is printed as 927 mm, not 925 mm), and defines flange thickness as excluding the raised face. Both corrections are reflected here; Series B NPS 38 and above follows Series A per the standard’s General Note (h).

Data imported 2026-11-05 08:05.