ASME B16.5 threaded (TH) flange: dimensions by class

Flange with tapered NPT thread, assembled without welding. For places where welding is not possible, with low vibration and moderate temperature.

Technical review Oct 2026 · Source: ASME B16.5-2020

Threaded in section. NPT thread (ASME B1.20.1) on the pipe.

StandardASME B16.5-2020

Classes150, 300, 400, 600, 900, 1,500, 2,500

Range in class 150NPS ½ to 24

Unitsmm, kg; hole and bolt in inches

Dimensions by pressure class

Choose the class and click a row: the drawing changes to the scale and dimensions of that diameter.

Threaded, class 150: dimensions in mm · raised face 1.6 mm · all types in class 150
NPS	DN	O	tf	X	Y	T	W	No. of holes	Hole Ø	Bolt Ø
½"	15	89	9.7	30	14	16	60.5	4	⅝"	½"
¾"	20	99	11.2	38	14	16	69.8	4	⅝"	½"
1"	25	108	12.7	49	16	18	79.2	4	⅝"	½"
1¼"	32	117	14.2	59	19	21	88.9	4	⅝"	½"
1½"	40	127	15.9	65	21	22	98.6	4	⅝"	½"
2"	50	152	17.5	78	24	25	120.6	4	¾"	⅝"
2½"	65	178	20.6	90	27	28	139.7	4	¾"	⅝"
3"	80	190	22.4	108	28	30	152.4	4	¾"	⅝"
3½"	90	216	22.4	122	30	32	177.8	8	¾"	⅝"
4"	100	229	22.4	135	32	33	190.5	8	¾"	⅝"
5"	125	254	22.4	164	35	37	215.9	8	⅞"	¾"
6"	150	279	23.9	192	38	40	241.3	8	⅞"	¾"
8"	200	343	26.9	246	43	44	298.4	8	⅞"	¾"
10"	250	406	28.4	305	48	49	362.0	12	1"	⅞"
12"	300	483	30.2	365	54	56	431.8	12	1"	⅞"
14"	350	533	33.3	400	56	57	476.2	12	1⅛"	1"
16"	400	597	35.1	457	62	64	539.8	16	1⅛"	1"
18"	450	635	38.1	505	67	68	577.8	16	1¼"	1⅛"
20"	500	698.5	41.1	559	71	73	635.0	20	1¼"	1⅛"
24"	600	813	46.0	663	81	83	749.3	20	1⅜"	1¼"

Threaded, class 300: dimensions in mm · raised face 1.6 mm · all types in class 300
NPS	DN	O	tf	X	Y	T	W	No. of holes	Hole Ø	Bolt Ø
½"	15	95	12.7	38	21	16	66.5	4	⅝"	½"
¾"	20	117	14.2	48	24	16	82.6	4	¾"	⅝"
1"	25	124	15.7	54	25	18	88.9	4	¾"	⅝"
1¼"	32	133	17.5	64	25	21	98.6	4	¾"	⅝"
1½"	40	155	19.0	70	29	22	114.3	4	⅞"	¾"
2"	50	165	20.6	84	32	28	127.0	8	¾"	⅝"
2½"	65	190	23.9	100	37	32	149.4	8	⅞"	¾"
3"	80	210	26.9	117	41	32	168.1	8	⅞"	¾"
3½"	90	229	28.4	133	43	37	184.2	8	⅞"	¾"
4"	100	254	30.2	146	46	37	200.2	8	⅞"	¾"
5"	125	279	33.3	178	49	43	235.0	8	⅞"	¾"
6"	150	318	35.1	206	51	46	269.7	12	⅞"	¾"
8"	200	381	39.6	260	60	51	330.2	12	1"	⅞"
10"	250	444	46.0	321	65	56	387.4	16	1⅛"	1"
12"	300	521	49.3	375	72	60	450.8	16	1¼"	1⅛"
14"	350	584	52.3	425	75	64	514.4	20	1¼"	1⅛"
16"	400	648	55.6	483	81	68	571.5	20	1⅜"	1¼"
18"	450	711	58.7	533	87	70	628.6	24	1⅜"	1¼"
20"	500	775	62.0	587	94	73	685.8	24	1⅜"	1¼"
24"	600	914	68.3	702	105	83	812.8	24	1⅝"	1½"

Up to NPS 3½, class 400 uses the same dimensions as class 600 (rows marked "= 600").

Threaded, class 400: dimensions in mm · raised face 6.4 mm · all types in class 400
NPS	DN	O	tf	X	Y	T	W	No. of holes	Hole Ø	Bolt Ø
½" = 600	15	95	14.2	38	22	16	66.5	4	⅝"	½"
¾" = 600	20	117	15.7	48	25	16	82.6	4	¾"	⅝"
1" = 600	25	124	17.5	54	27	18	88.9	4	¾"	⅝"
1¼" = 600	32	133	20.6	64	28	21	98.6	4	¾"	⅝"
1½" = 600	40	155	22.4	70	32	22	114.3	4	⅞"	¾"
2" = 600	50	165	25.4	84	37	28	127.0	8	¾"	⅝"
2½" = 600	65	190	28.4	100	41	32	149.4	8	⅞"	¾"
3" = 600	80	210	31.8	117	46	35	168.1	8	⅞"	¾"
3½" = 600	90	229	35.1	133	49	40	184.2	8	1"	⅞"
4"	100	254	35.1	146	51	37	200.2	8	1"	⅞"
5"	125	279	38.1	178	54	43	235.0	8	1"	⅞"
6"	150	318	41.1	206	57	46	269.7	12	1"	⅞"
8"	200	381	47.8	260	68	51	330.2	12	1⅛"	1"
10"	250	444	53.8	321	73	56	387.4	16	1¼"	1⅛"
12"	300	521	57.2	375	79	60	450.8	16	1⅜"	1¼"
14"	350	584	60.5	425	84	64	514.4	20	1⅜"	1¼"
16"	400	648	63.5	483	94	68	571.5	20	1½"	1⅜"
18"	450	711	66.5	533	99	70	628.6	24	1½"	1⅜"
20"	500	775	69.8	587	102	73	685.8	24	1⅝"	1½"
24"	600	914	76.2	702	114	83	812.8	24	1⅞"	1¾"

Threaded, class 600: dimensions in mm · raised face 6.4 mm · all types in class 600
NPS	DN	O	tf	X	Y	T	W	No. of holes	Hole Ø	Bolt Ø
½"	15	95	14.2	38	22	16	66.5	4	⅝"	½"
¾"	20	117	15.7	48	25	16	82.6	4	¾"	⅝"
1"	25	124	17.5	54	27	18	88.9	4	¾"	⅝"
1¼"	32	133	20.6	64	28	21	98.6	4	¾"	⅝"
1½"	40	155	22.4	70	32	22	114.3	4	⅞"	¾"
2"	50	165	25.4	84	37	28	127.0	8	¾"	⅝"
2½"	65	190	28.4	100	41	32	149.4	8	⅞"	¾"
3"	80	210	31.8	117	46	35	168.1	8	⅞"	¾"
3½"	90	229	35.1	133	49	40	184.2	8	1"	⅞"
4"	100	273	38.1	152	54	41	215.9	8	1"	⅞"
5"	125	330	44.4	189	60	48	266.7	8	1⅛"	1"
6"	150	356	47.8	222	67	51	292.1	12	1⅛"	1"
8"	200	419	55.6	273	76	57	349.2	12	1¼"	1⅛"
10"	250	508	63.5	343	86	65	431.8	16	1⅜"	1¼"
12"	300	559	66.5	400	92	70	489.0	20	1⅜"	1¼"
14"	350	603	69.8	432	94	73	527.0	20	1½"	1⅜"
16"	400	686	76.2	495	106	78	603.2	20	1⅝"	1½"
18"	450	743	82.6	546	117	79	654.0	20	1¾"	1⅝"
20"	500	813	88.9	610	127	83	723.9	24	1¾"	1⅝"
24"	600	940	101.6	718	140	92	838.2	24	2"	1⅞"

Up to NPS 2½, class 900 uses the same dimensions as class 1500 (rows marked "= 1500").

Threaded, class 900: dimensions in mm · raised face 6.4 mm · all types in class 900
NPS	DN	O	tf	X	Y	T	W	No. of holes	Hole Ø	Bolt Ø
½" = 1500	15	121	22.4	38	32	22	82.6	4	⅞"	¾"
¾" = 1500	20	130	25.4	44	35	25	88.9	4	⅞"	¾"
1" = 1500	25	149	28.4	52	41	28	101.6	4	1"	⅞"
1¼" = 1500	32	159	28.4	64	41	30	111.1	4	1"	⅞"
1½" = 1500	40	178	31.8	70	44	32	124.0	4	1⅛"	1"
2" = 1500	50	216	38.1	105	57	38	165.1	8	1"	⅞"
2½" = 1500	65	244	41.1	124	64	48	190.5	8	1⅛"	1"
3"	80	241	38.1	127	54	41	190.5	8	1"	⅞"
4"	100	292	44.5	159	70	48	235.0	8	1¼"	1⅛"
5"	125	349	50.8	190	79	54	279.4	8	1⅜"	1¼"
6"	150	381	55.6	235	86	57	317.5	12	1¼"	1⅛"
8"	200	470	63.5	298	102	64	393.7	12	1½"	1⅜"
10"	250	546	69.8	368	108	71	469.9	16	1½"	1⅜"
12"	300	610	79.2	419	117	76	533.4	20	1½"	1⅜"
14"	350	641	85.9	451	130	83	558.8	20	1⅝"	1½"
16"	400	705	88.9	508	133	86	616.0	20	1¾"	1⅝"
18"	450	787	101.6	565	152	89	685.8	20	2"	1⅞"
20"	500	857	108.0	622	159	92	749.3	20	2⅛"	2"
24"	600	1041	139.7	749	203	102	901.7	20	2⅝"	2½"

Threaded, class 1500: dimensions in mm · raised face 6.4 mm · all types in class 1500
NPS	DN	O	tf	X	Y	T	W	No. of holes	Hole Ø	Bolt Ø
½"	15	121	22.4	38	32	22	82.6	4	⅞"	¾"
¾"	20	130	25.4	44	35	25	88.9	4	⅞"	¾"
1"	25	149	28.4	52	41	28	101.6	4	1"	⅞"
1¼"	32	159	28.4	64	41	30	111.1	4	1"	⅞"
1½"	40	178	31.8	70	44	32	124.0	4	1⅛"	1"
2"	50	216	38.1	105	57	38	165.1	8	1"	⅞"
2½"	65	244	41.1	124	64	48	190.5	8	1⅛"	1"

Threaded, class 2500: dimensions in mm · raised face 6.4 mm · all types in class 2500
NPS	DN	O	tf	X	Y	T	W	No. of holes	Hole Ø	Bolt Ø
½"	15	133	30.2	43	40	28	88.9	4	⅞"	¾"
¾"	20	140	31.8	51	43	32	95.2	4	⅞"	¾"
1"	25	159	35.1	57	48	35	108.0	4	1"	⅞"
1¼"	32	184	38.1	73	52	38	130.0	4	1⅛"	1"
1½"	40	203	44.4	79	60	44	146.0	4	1¼"	1⅛"
2"	50	235	50.8	95	70	51	171.4	8	1⅛"	1"
2½"	65	267	57.2	114	79	57	196.8	8	1¼"	1⅛"

Scale drawing

Section drawing, proportional to the table dimensions (mm).

O = outside diameter · tf = thickness without raised face · X = hub diameter at base · Y = overall length without raised face · T = minimum thread length · W = bolt circle. * Weight estimated from geometry in carbon steel.

Frequently asked questions

What is the asme b16.5 threaded (th) flange: dimensions by class used for?

Flange with tapered NPT thread, assembled without welding. For places where welding is not possible, with low vibration and moderate temperature.

Do the dimensions include the raised face?

No. Since the 2017 edition, the thickness (tf) and length (Y) in ASME B16.5 are measured without the raised face. Add 1.6 mm for classes 150 and 300 and 6.4 mm from class 400 upward.

In which materials does Dustre supply it?

A105 and A350 LF2 carbon steel, F304L and F316L stainless, F51/F60 duplex, F53/F55 super duplex, F11, F22 and F91 Cr-Mo, nickel alloys and titanium, forged and machined with 3.1 certificate.

Threaded in special alloysForged and machined at Dustre, in any class, with 3.1 certificate.

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